We-disease Model: A conceptualization of couples’ dyadic coping when dealing with chronic physical or mental illness

Abstract

Chronic physical illnesses and mental disorders usually do not occur in isolation, but rather within a social context. The course of a disease is influenced not only by medical treatment but also by close relatives, friends, and especially partners, who themselves are affected by illness-related restrictions or care-giver burden. However, to date, the social context is not been adequately considered, with the social component of the biopsychosocial model often receiving only limited attention. With the We-Disease Model (WDM), we promote a systemic/interpersonal view of mental disorders and somatic illnesses with a particular focus on the couple relationship and joint coping efforts. To address processes over time, we propose the Trajectory Model of We-Disease (TMWD) to consider the factors that influence we-disease processes and propose various trajectories over time. Finally, we address the significance of this perspective, which is conceptualized in the term “we-disease”, for health interventions.

Chronic somatic diseases, such as cardiovascular diseases, cancer, diabetes and chronic respiratory diseases, are the major causes of morbidity and mortality worldwide (World Health Organization, 2022a). For instance, half of the adult population in the USA have at least one chronic health condition (Ward and Schiller, 2013). An additional 13% are living with a mental disorder (World Health Organization, 2022b).

Chronic health issues are characterised by the need for ongoing intervention with medical products, treatment, services, or special equipment, and the disease places limitations on self-care, independent living, or social interactions (Agency for Healthcare Research and Quality, 2023). Thus, the treatment and ramifications of these chronic health conditions lead to considerable and increasing public health and economic burden (Hacker, 2024).

The course of a disease is influenced not only by medical treatment but also by close relatives, friends, and especially partners, who themselves are affected by illness-related restrictions or care-giver burden. Even though it is known that individual and relational outcomes depend not only on individual characteristics but also on couple-level interactions and differences between couples exist (Brauer and Proyer, 2019). To date, there is no homogenous and consistent scientifically based model on how couples deal with such chronic stress. However, such a comprehensive model could be particularly useful in providing a uniform theoretical framework for the increasing volume of research in this field and in enabling the development of clinical interventions. Thus, we propose a We-Disease Model (WDM) that is underpinned by two primary pillars: (a) a systematic review that provides theoretical clarification (Weitkamp and Bodenmann, submitted), and (b) existing theoretical conceptualizations of common or communal coping among couples confronted with chronic illness which will be briefly mentioned in the following paragraph and taken up again below in more detail in relation to the We-Disease Model.

Even though model development of dyadic coping, communal coping, and similar concepts of we-disease started in the 1990s and were often rooted in the Systemic Transactional Model (STM; Bodenmann, 1997, 2005), the term we-disease was first coined by Kayser and colleagues (2007) based on a qualitative study, where one partner of a breast cancer patient described the illness as a common experience using the term “we-disease” (p. 410). In this study, couples who were mutually responsive defined the cancer experience as a dyadic stressor – a “we-stress” – that affected both of them.

Early theoretical conceptualizations focused on general stress experiences in couples. For instance, the Systemic Transactional Model (STM; Bodenmann, 1997, 2005) was initially developed in the context of daily hassles and emphasized the interdependence of stress experiences among partners ¹ (joint appraisals; we-stress) as well as how couples deal with these stressors together (common dyadic coping). Further, R. F. Lyons et al. (1998) developed a communal coping model for unspecified stressors and for families and other groups of people which was extended by Afifi et al. (2020), who postulated the Extended Theoretical Model of Communal Coping (TMCC) which aims at families and communities dealing with various stressors.

In later extensions and elaborations of R. F. Lyons et al.'s (1998) model, Helgeson et al. (2018) and Rentscher (2019) focused explicitly on couple’s communal coping when dealing with chronic illness, while Lewis et al. (2006) conceptualized health behaviour change in couples with one partner facing a health threat. Further influential models specifically for chronic illness in couples are (1) the Developmental–Contextual Model (DCM; Berg and Upchurch, 2007), (2) the Theory of Dyadic Illness Management (Lyons and Lee, 2018), and (3) the Cognitive-Transactional Model (CTM) of couples’ adaptation to chronic illness (Badr and Acitelli, 2017). For sudden, disruptive medical events Cornelius (2021) conceptualized co-rumination in couples within the Dyadic Disruption Theory. The distinction between social support and caregiving made by Revenson et al. (2016) is interesting, whereby caregiving in the context of chronic illnesses is associated with a much higher degree of responsibility and forms the caregivers’ identity when compared with social support.

A number of theoretical models aim at common/communal/collaborative couple’s coping with specific illnesses. These models appear to have been developed in parallel and independently across different disciplines, such as cancer and diabetes care. For cancer, the Relational-Cultural Coping Model (RCCM) was published with a later extension (Kayser and Acquati, 2019; Kayser et al., 2007). Additionally, a conceptual overview integrated findings for dyads dealing with cancer (Live With Love Conceptual Framework; Li and Loke, 2015).

Further models aimed at family members dealing jointly with chronic illnesses, like the dyadic approach to chronic illness management (Martire and Helgeson, 2017) or Basinger´s (2018) expansion and refinement of the appraisal dimension in the context of families managing one member’s type 2 diabetes. Another addition to the communal coping landscape is the Dyadic-Regulation Connectivity Model, which emphasizes the continuous, parallel interplay between individual and dyadic appraisal and coping processes (Karademas, 2022). A particular feature of the model is the organization of illness representations, coping and outcomes into network hubs.

There are, therefore, already a number of approaches and models that address a dyadic or interpersonal perspective on coping with chronic or serious illnesses. Nevertheless, the different models address or emphasize very different aspects, and there is still no integrative, holistic model that can be applied to both mental disorders and somatic illnesses in couples. The aim of this article is to propose such a model.

The We-Disease Model

The proposed We-Disease Model (WDM) attempts to present a new model for research and clinical or health-related interventions from a thorough theoretical lens, based on previous models. It is based on the STM (Bodenmann, 1995, 2005) and also incorporates further theoretical conceptualizations mentioned above.

At the centre of the WDM is the couple consisting of partner A and partner B, with one or both facing illness-related stress which in turn is part of more general life stress including major and minor stressors. The couple’s we-disease process consists of individual and dyadic appraisals of the illness and subsequent individual and dyadic goals how to deal with the situation. This is followed by individual and dyadic coping activities and subsequently by attributions of the dyadic coping outcomes. The we-disease process does not happen in a vacuum but rather is related to the current individual- and couple-level psychological and physical well-being, relational aspects, and the couple’s spirituality and faith. Additionally, the couple’s we-disease process is influenced by context factors from micro to macro, like children, extended family, social network, the medical system, zeitgeist and culture (see Bronfenbrenner, 1979). The different components of the WDM will be subsequently described in more detail in two models. The first model addresses factors related to we-disease (see Figure 1), the second model depicts the cyclical nature of we-disease leading to specific trajectories of individual and couple outcomes (see Figure 2).

Figure 1.

We-Disease Model for couples coping with illness-related stress.

Figure 2.

We-Disease Trajectory Model for couples coping with illness-related stress.

Partners A and B and the couple level

In the WDM, transactional processes between both partners are assumed, whereby three entities are distinguished: partner A, partner B, and the couple, which are intensely interrelated (see Figure 1). Both partners contribute certain personality traits (e.g., big five, frustration tolerance, perseverance, optimism, authenticity, stress resilience, attachment style, control beliefs, self-efficacy, attribution style, etc.), individual motives (personal and relationship-related motivation), as well as skills and competencies (e.g., communication, coping, emotion regulation, impulse control, social skills, etc.). On the one hand, these are located in person A and B, but on the other hand, they are strongly interdependent and influence each other reciprocally, shape and maintain themselves. In this line, Helgeson et al. (2018) referred to an interdependent personality orientation or preference for independence in their approach, whereby some people prefer to solve problems on their own, while others favour tackling them together.

At the couple level, various aspects play an important role in the WDM. On the one hand, there is the fit between the two partners in terms of their individual personality traits (e.g., the big five), their motives, and their competencies, like congruence and/or similarity mentioned by Revenson (1994). On the other hand, there are genuinely dyadic phenomena such as couple communication, dyadic coping, shared commitment, shared goal orientations, shared visions and feelings of we-ness, intimacy and closeness. They all play an important role for we-disease and influence the dyadic processes in the context of dealing alone or together with the illness or mental disorder. In their model, Affifi et al. (2020) also referred to the couple’s communication quality. However, much more dyadic aspects play a crucial role, in the question of whether partners engage in a joint approach of dealing with the illness or cope individually.

General stress

Stress is at the beginning of the we-disease process and triggers it. Without stress caused by illness or mental disorder, there is no reason for a person or the couple to deal with an issue. However, the stress caused by the illness or mental disorder should not be viewed in isolation. Even before the diagnosis, both partners and the couple had to cope with various stressors, so that the illness-related stress is added to the existing background stress and further increases any pre-existing burden. This often results in a pile-up of stress, in which daily hassles, critical life events, and developmental tasks, as well as illness-related stress accumulate in one or both partners. In addition to the background stress they already experience, critical life events related to the illness (e.g., loss of job, financial strain, loss of social contacts, multiple restrictions, and lifestyle changes) and various daily hassles come into play (taking on tasks that were previously performed by one’s partner, increased effort required to run errands, caring for the patient, and accompanying the patient to medical appointments, etc.). This indirectly illness-related stress can be accompanied by experiences of conflict, grief, or helplessness in relation to one’s previous life, the loss of family routines, and the loss or change of previous visions of life plans and the relationship that have to be adapted or given up. Additionally, it should be noted that parallel to the increase of some stressors other stressors may fall away, for example, work-related stress when being on sick leave or reduction of social obligations.

Illness-related stress

Within the overall stress experience, illness-related stress refers to stress that is directly related to the disease (severity, symptom burden), the course of the disease (first symptoms, diagnosis, early stage of the disease, advanced stage, lethal stage), and the prognosis (e.g., progressive decline/stable/progressive improvement, un-/predictable course, non-/visible signs of the disease). However, illness-related stress also includes stigma (e.g., Afifi et al., 2020), interference from the partner or their control and coercion or overprotection (Coyne and Smith, 1991; Helgeson et al., 2018), but also stress related to illness management strategies that may be more amenable to partner involvement than others (Helgeson et al., 2018). This type of stress also involves dysfunctional individual or dyadic coping (e.g., protective buffering), tensions or conflicts arising from the illness and its treatment, emotional alienation or misunderstandings due to different experiences within the patient or caregiver roles. Many of these illness conditions were already described in detail by Berg and Upchurch (2007), such as the phase of illness (e.g. stages in cancer development) as well as illness conditions. However, an additional interesting aspect relates to the illness trajectory and the caregiver’s life stage. Revenson et al. (2016) describe illness onsets that may be “on-time” versus “off-time”. This means that a diagnosis may seem more or less appropriate depending on the patient’s age, for example if a very young person has Parkinson’s disease, which typically affects older people, this would be considered “off-time” and goes along with higher distress in both, the ill person and the caregiving partner who is not at all mentally prepared for their role at this stage of life.

Appraisals

Shared appraisals play a major role in a number of previous illness-related dyadic coping or we-disease models. Berg and Upchurch (2007) referred to dyadic appraisal with regard to illness representation, illness ownership, and shared stressors. Kayser et al. (2007) proposed two steps in shared appraisals. In the first step, partners need to appraise the stressor as a dyadic stress, followed in a second step by an emotional response and validation from the partner. Kayser and Acquati (2019) mentioned that shared appraisals serve joint meaning making.

The role of individual and communal appraisals is also a central component in the communal coping model by R. F. Lyons et al. (1998). Building on Lyons et al.'s model, Helgeson et al. (2018) interpreted the relevance of shared illness appraisal in a way that other support interactions beyond communal coping may also be understood by the couple as collaboration even though they were carried out individually. Also, Lewis et al. (2006) state that partners’ appraisals of health behaviour threat are meaningful for partners to create the motivation to respond to this threat.

The most differentiated conceptualization was proposed in the STM (Bodenmann, 1995, 2000), where primary and secondary appraisals on an individual and dyadic level were addressed, proposing an extension of the appraisals conceptualized in the transactional model by Lazarus and Folkman (1984), where the primary appraisal represented an assessment of the situation in terms of its stress relevance, personal valence, and threat. The secondary appraisal was related to the question of whether the person had sufficient resources to cope with the demands. The dyadic extension of the appraisal processes, proposed by Bodenmann (1995, 2000), include a number of primary (1a to 1d) and secondary appraisals (2a to 2c) which will be described shortly in turn.

The primary appraisals encompass an appraisal of the stressful situation, for instance a cancer diagnosis or a multiple sclerosis relapse, partner A’s own appraisal of the situation (1a: “How demanding is the situation?”), partner A’s appraisal of partner B’s perception of the stressful situation based on current situational cues or grounded in previous experiences and knowledge of their partner’s personality characteristics or potential reactions (1b: “How demanding does my partner perceive the situation?”). Thirdly, the appraisal that partner A recognizes that partner B has perceived their assessment (1c: “Does my partner realize my appraisal of the situation?”). The fact that the other partner understands one’s subjective stress experience and correctly decodes one’s own stress signals is also likely to have a positive impact on the further coping process. And lastly, based on a verbal exchange or an intuitive read of the situation, partner A compares their own assessment with that of partner B (1d: “Do we agree in our appraisals?”; comparison, yielding the basis for we-disease appraisal and common/joint DC). If the two partners’ assessments diverge, several paths may emerge. One option is to revert to the first step of the appraisal and re-evaluate it, repeating the entire assessment process to gather more information and re-examine the partner’s perspective in a new light (see re-appraisal in Lazarus and Folkmans original model; 1984). Furthermore, it is possible to adopt the partner’s appraisal despite existing dissonances. The focus of the primary appraisal is whether their own well-being or that of their partner or the dyad is at risk. The secondary appraisal, however, focuses on the available individual, dyadic, and extradyadic resources to cope with the stressor similar to Lazarus and Launier (1978). Here, similar to the primary appraisal process described above, one’s own individual appraisal of coping resources (2a: own resources) is supplemented by partner A’s assessment of partner B’s appraisal (2b: available partner resources) and the comparison of both assessments (2c: common/joint resources). In the cascade model by Bodenmann (2000, 2005) these different primary and secondary appraisals would lead to a stepped process of response reactions to stress: It is assumed that the stressed partner first tries to cope individually with the stress. If this does not lead to a solution of the stress, partners resort to dyadic coping, followed by social support from friends or kin and finally seeking professional help. The Dyadic Regulation Connectivity Model, however, proposes that individual and dyadic appraisals and coping efforts are parallel and interactive processes (Karademas, 2022).

Goals

In addition to primary and secondary appraisal, goals and expectations play an important role in the STM (Bodenmann, 1995, 2000) and thus also the WDM. As Lazarus and Folkman (1984) have elaborated, goals can include reducing, minimizing, overcoming, or tolerating a stress experience. Cohen and Lazarus (1979) described the central goals of the coping process as (a) maintaining a positive self-image, (b) restoring emotional balance, and (c) continuing satisfactory social relationships. The overarching goals in the original transactional stress model were changing the stressful person-environment relationship (problem-focused coping) and emotion regulation (emotion-focused coping; Lazarus and Folkman, 1984). This addresses assimilative (adaptation of the environment to the person), accommodative (adaptation of the person to the environment), self-regulatory (maintenance of self-esteem) and socially regulatory goals (maintenance of social integration). In the context of close relationships, both individual and joint goals need to be considered. Thus, different goal dimensions can be distinguished (individual vs. dyadic goals, short- vs. long-term goals, situational vs. general goals, problem- vs. emotion-focused goals, illness-related vs. relationship-focused goals, etc.). In addition to the subjective appraisals of both partners, the STM postulates shared goals, which are understood as syntheses of the shared appraisals (1d and 2c appraisals). Joint goals are the basis for the coordination of problem-focused or emotion-focused dyadic coping (Kayser et al., 2007).

Dyadic coping

Several review articles have already systematically compiled the various facets of dyadic coping (e. g., Falconier and Kuhn, 2019; Weitkamp and Bodenmann, 2022). In connection with we-disease, two theoretical approaches have emerged as the most prominent, the communal coping model by R. F. Lyons et al. (1998), further developed by Helgeson et al. (2018). The terms communal or collaborative coping originate from these models (Berg and Upchurch, 2007; Helgeson et al., 2018; Lyons et al., 1998), while Bodenmann (1995) first introduced the notion of dyadic coping (DC). DC involves (a) in the STM, supportive, delegated, common/joint and negative DC (Bodenmann, 1995, 2000), (b) in the DCM, it encompasses uninvolved, supportive, collaborative, and controlling behaviours (Berg and Upchurch, 2007), (c) in the communal coping model with its extensions, as the name implies, the term communal coping is used (Helgeson et al., 2018; Lyons et al., 1998), and (d) in a study on relationship-focused coping, negative forms of dyadic coping were assessed, like overprotection or protective buffering (Coyne and Smith, 1991). Berg and Upchurch (2007) also describe dyadic coping along a continuum of involvement, ranging from the partner’s uninvolvement – where the patient perceives that they are coping independently – to overinvolvement, where the patient perceives the partner as controlling or engaging in misdirected helping behaviours.

Attributions

Attributions play a dual role in relation to we-disease. On the one hand, we assume that the question of how much assumed responsibility or feelings of guilt the partner bears for their illness (e.g., despite years of warnings, they were a chain smoker and thus may have contributed to the cancer through their behaviour) could influence their appraisals, goals and commitment to joint dyadic coping within the framework of we-disease. If the illness is viewed as fate that has struck the partner unexpectedly and for which they bear no responsibility, it may be easier for the partner to engage in we-disease.

Second, attributions should also be considered when assessing the success or failure of the couple’s we-disease approach. What did partner A and/or partner B contribute individually, what did both contribute jointly to coping with the illness, and how successful was it? These assessments can be made on both the instrumental and the emotional level. Depending on the attributions, individual and dyadic self-efficacy expectations are formed, which are likely to play an important role in future stress episodes. In this context the notion of meaning making (Kayser and Acquati, 2019) may play an important role (what did the couple learn from the experience). Further facets of attributions are outcome efficacy and couple efficacy described by Lewis et al. (2006). Outcome efficacy is analogous to the concept of outcome expectations in value-expectancy models of health behaviour and pertains to the couple’s perception of the effectiveness of communal coping in initiating and sustaining behaviour change. In contrast, couple efficacy refers to the couple’s confidence that, together, they are capable of engaging in dyadic coping efforts.

The we-disease process is not happening within a vacuum. Both, partner A and partner B contribute individually to the success or failure of the we-disease process. This contribution is based on their personality, as previously described, as well as on their personal resources concerning their physical and mental well-being, their spirituality and faith and on relational aspects of the couple which will be addressed in the following paragraphs. Some of these aspects on the individual and couple-level will influence we-disease (for example, personality) others will have a bidirectional, circular association. For example, self-efficacy will influence the perception of we-disease, and a successful we-disease approach will again have effects on future individual and dyadic self-efficacy.

Physical and psychological well-being

Psychological well-being is both an independent and dependent variable in the context of we-disease. As an independent variable, it influences both individual and intra-couple processes – such as appraisals, goals, dyadic coping, and attributions. This influence is shaped by current psychological states (e.g., mood, stress level, physical and psychological energy, physical fitness, hope, trust) as well as through more generally available psychological resources (e.g., life satisfaction, relationship satisfaction, sense of coherence, resilience). On the other hand, psychological well-being may be a consequence of the success or failure of joint dyadic coping in dealing with the illness. Helgeson et al. (2018) considered this aspect (stress level, sense of control, self-efficacy) as a mediator in their model. Indicators of somatic health may be subjective and reported by individuals themselves, like physical health-related quality-of-life, physical symptoms, pain severity, and functional impairment or more objective, like patient functioning or mortality (Robles et al., 2014).

Relational aspects

Relationship aspects (as mediator, antecedent or outcome) are considered in most we-disease approaches (DCCM; Berg and Upchurch, 2007; STM; Bodenmann, 1995, 2000; CCM; Helgeson et al., 2018; RCCM; Kayser et al., 2007) as well as Afifi et al.'s approach (2020). Relational aspects are manifold and encompass amongst others relationship satisfaction, commitment, dyadic self-efficacy, feeling of we-ness, cohesion, or relational gratitude (Rentscher, 2019). An attitude of relationship awareness as described by Kayser et al. (2007) may be beneficial. This involves considering one’s relationship within the context of illness. On the one hand, this means being aware of the impact of the illness on the partner and the relationship, and on the other hand, thinking about strategies to sustain the relationship despite the additional demands imposed by the illness.

Another important relationship-related aspect is equity or fairness in terms of contributions to joint dyadic coping, even if this balance will often not be experienced during acute stressful phases of the illness, but before or after it. For example, one may invest more during acute stressful phases of the partner’s illness, but have previously received more than one provided, or the return may come at a later stage. Additionally, giving and receiving may occur on different levels. While partner A is taking on caregiving tasks, partner B may have the capacity to provide emotional support to help manage difficult emotions experienced during the illness. This aspect is particularly taken into account in the RCCM term mutuality, where each partner participates as much as possible in the shared experience (Kayser et al., 2007). Motivational aspects are indirectly part of the model, where for instance high relationship satisfaction and commitment will increase the motivation to engage in we-disease, whereas low relationship satisfaction or commitment would reduce the motivation.

Spirituality, faith

Spirituality can be defined as an individual’s belief in a power beyond their own existence and a sense of relationship or connection with this power or force in the universe that transcends the present context of reality (King et al., 1999). Faith relates to the personal relationship with God or something greater and is more personal, subjective, and deeper than organized religion (Paul Victor and Treschuk, 2020).

Quite often, spirituality and faith are seen as resources when dealing with chronic or terminal health conditions (Kaye and Raghavan, 2002). For example, in a review of older adults coping with dementia, spirituality appeared to facilitate acceptance of the disease, sustain relationships and hope, and help individuals find meaning in their lives, thereby enhancing their quality of life (Agli et al., 2015). However, spirituality and faith can also function as negative factors. For example, an external locus of control (referring to God) when suffering from an illness can lead to passivity or even to a spiritual crisis (Gall and Grant, 2005). In the context of the WDM, spirituality and faith are viewed as individual as well as couple-level factors. A shared belief system between partners may provide strength and meaning for both. A more critical aspect of religious practices and spirituality can arise when partners influence each other based on their religious beliefs or when couples choose to forego necessary medical procedures or seek healing through (potentially questionable) spiritual practices or faith healers. In a Pakistani study, couples with chronic health conditions were seeking help together from spiritual healers (Arshad and Bibi, 2024). When faith is not shared within a couple, it can lead to tensions and emotional distance, especially at the end of life, this may create additional stress and burden (Gardner, 2008).

Context

The couple is not isolated, but part of a broader context. Similar to Bronfenbrenner’s ecological systems theory, the couple is embedded in, influenced by interconnected environmental systems from the micro to the macro level (Bronfenbrenner, 1979). The micro level encompasses the couple’s nuclear family, e.g. their children. On the meso level, the extended family may play a role in the couple’s coping with a chronic health condition, also the greater social network and the interaction with medical professions. On the macro level, the particular culture and zeitgeist will influence the we-disease process. These levels will be described in more detail below.

Children

Depending on the life phase of the couple, there may be children who are under-age or already adults. Young children are affected by the chronic illness in multiple ways, but may also represent further stress for the couple dealing with the illness. Young children can be an additional burden, as they themselves need protection and care, but resources are limited due to the chronic illness of one parent, which can trigger feelings of insecurity and guilt within the ill person or partner. In adolescent children, the illness of a parent can lead to parentification issues (e.g., Jurkovic, 1997) as children (often girls) take on caregiving tasks and responsibilities for their parents or siblings that are not age-appropriate. For adult children, caregiving adds to their own existing stress (work, relationships, own children), which means multiple burdens. Since children can play an important role in both senses (as stressors and potential resources), they are part of the WDM. Adult children in particular can be of great importance as a source of support and relief for the ill as well as the caregiving partner. This microsystem level is bi-directional, meaning that the couple’s coping with the illness will have an influence on the nuclear family, while simultaneously, the way close family members manage the illness impacts the couple.

Extended family/social network/medical system

In the WDM, social resources outside the couple or the nuclear family also play an important role. The size of the network is probably less important than the actual support provided by relatives, friends, acquaintances, and professional experts. Bodenmann (2005) proposed the cascade model within the STM, according to which individuals first try to cope with stress on their own, then resort to dyadic coping, and, if further support is needed, turn to their extended social network until they finally seek professional help (physicians, physical therapists, nutritionists, psychotherapists etc.). Various factors play a role in understanding the availability of caring and social support from various protagonists and systems (couple, nuclear family, greater family system, kin and friends, medical system), including the duration and severity of the illness or mental disorder and its progression (chronic, recurrent) and presumed temporal sequences (who is available at what point in time). However, the couple may also experience social pressures from their network and family, for example, to fulfil a caregiving role or dis-/continue certain treatments (see also discussion on gender roles and culture below).

Regarding the medical system, a great variety exists between countries, thus creating differences in treatment and care options that will affect illness trajectories and couples’ illness experiences differently, enabling or hindering we-disease processes. Overall, having the partner (or another family member) at their side during consultations with health-care professionals was experienced as empowering for patients (Årestedt et al., 2018). In this case, a partner would be an advocate for the patient’s interests when interacting with medical staff. Further, we-disease processes may enable or impede compliance and adherence, depending on the couple’s joint appraisal, illness beliefs, and dyadic coping efforts.

Zeitgeist, culture

While Zeitgeist refers to the historically specific expression of a culture, represented in dominant patterns of thought and interpretation that shape the perception of reality in a particular era (e.g., through scientific paradigm shifts, media discourse, or socioeconomic developments), culture, on the other hand, refers more to enduring, deeply rooted norms, values, and worldviews that shape a society over long periods of time. Zeitgeist and cultural discourses influence concepts such as family, illness, self, responsibility, and intimacy. We-disease processes are shaped by both aspects. The Zeitgeist influences how compatible such WDM is. In phases, where close relationships and social networks are emphasized more strongly (e.g., in the context of postmodern or systemic conceptualizations), relational perspectives gain legitimacy. In recent years, there has been a clear trend toward process-oriented, context-sensitive, and dimensional models of mental disorders – away from categorical, deficit-oriented diagnoses (see Hofmann and Hayes, 2019), representing a context favourable to WDM. In more collectivist cultures (Asian or Latin cultures), an interpersonal conceptualization of disease as in WDM may be more self-evident from the outset. Lyons et al. (1998) and Afifi et al. (2020) already emphasized the importance of considering the cultural context, pointing to the influence of collective versus individualistic cultural influences (interdependent-independent orientation). In individualistic cultures, an emphasis on independence and autonomy may foster the use of primary control strategies, trying to individually master health challenges, as opposed to more collaborative forms of coping (Berg and Upchurch, 2007). For people who are strongly individualistic and self-focused, it can be more challenging to get a handle on we-disease and it may be necessary to do more to persuade people of the benefits of WDM.

However, in more collectivist cultures, like Asian and Hispanic cultures, the expectation is widespread that the patient should be protected. For communication of serious diagnoses, medical staff should rather speak with relatives and partners, rather than with the patients themselves (Berg and Upchurch, 2007). This form of overprotection contradicts WDM and therefore does not automatically provide a better basis for joint appraisals and joint dyadic coping within the couple. Additionally, there are significant variations in prevalence of specific illnesses within different cultures and subcultures that should be considered as part of the model.

Cultural values and norms shape expectations for the level of interdependence among partners in a committed relationship (Berg and Upchurch, 2007). Quite often in western cultures, the spouse is viewed as the primary source of support, while in Asian cultures, individuals may turn to their children (Arshad and Bibi, 2024) or in Latin cultures, individuals may seek support from other family members (Lin et al., 2019). In view of the high divorce rates, more and more older individuals are single for longer periods of time. In these cases, we-disease processes may take place with a close friend or relative (Berg and Upchurch, 2007).

Furthermore, gender role norms and stereotypes are a central factor of zeitgeist and culture that profoundly influence the perception, attribution, and coping of illness in a couple context and thus also shape the understanding and application of WDM. The WDM considers gender not only as a demographic variable, but as a socially constructed, performative script that influences both individual experience and dyadic patterns (Eagly and Wood, 2012). Interpersonal interventions based on the WDM should reflect on, explain, and, if necessary, deconstruct stereotypical role expectations (e.g., work on emotional openness, equal distribution of care roles, or the validation of male vulnerability).

Current gender role expectations prescribe women a nurturing and caring role (Revenson et al., 2016). Worldwide, women are the ones who carry out most of the care work (Meleis and Lindgren, 2002) and often feel a strong sense of responsibility to care for their ill partner (Forssén et al., 2005). Women are more often caregivers than men, they take on more hours of caregiving and more hands-on caregiving tasks. Women more often take on emotional coping, relieve their partner’s stress, organize appointments with physicians and other specialists, and stabilize everyday life and children. Even when women are the patients, they feel more responsible for their close relationships than men (Helgeson et al., 2018). Men, on the other hand, are more often socialized to be independent, stoic, or performance-oriented, which can lead them to articulate illness less well, seek help less often, or avoid emotional closeness, hindering a we-disease approach.

Emotional distress is more marked among women caregivers than man (National Alliance for Caregiving and American Association of Retired Persons, 2015; Revenson et al., 2016). In particular providing unpaid care whilst upholding work- and family-related tasks and receiving little recognition from others often leads to psychological distress. For these and other reasons, women seem to struggle more than men to view their new caregiving role positively. Men appear more flexible to take on caregiving tasks by expanding their masculine gender role (Zygouri et al., 2021). When economic resources were available, caregiving men would get support by paid help to deal with caregiving and household chores (Revenson et al., 2005). Even though in Latin cultures, the cultural value of familismo may enhance common dyadic coping, cultural taboos around not talking about a disease and men’s gender role expectations as one of not sharing emotions (Sanabria et al., 2024) may hinder the initiation and maintenance of we-disease processes.

From a we-disease perspective, in heterosexual relationships, a joint appraisal and distribution of caregiving and household responsibilities between partners regardless of gender and patient status may be worthwhile. In which areas can in particular the female caregiver be provided with relief? Which household tasks can a person with a chronic illness still perform, and in which areas do they require support and alleviation? Additionally, jointly exploring options for getting outside help may also be seen relevant for joint dyadic coping through the we-disease lens. Different patterns may emerge in same-sex couples, where WDM would be compatible with queer-theoretical perspectives on coping, power, and connectedness.

Regarding culture, while for couples with the same cultural background the partner may serve as a reinforcing power to the patient’s care expectations, in multicultural or binational couples, these expectations may differ and counteract with helpful we-disease processes. Binational couples are particularly significant in the context of WDM, not only because they often have to negotiate intercultural differences in everyday life, but also because their approach to illness, psychological stress, and dyadic coping takes place under conditions of cultural hybridity.

We-disease is also embedded in a field of tension between minorities and the dominant culture and the mistrust in health services that grew out of systems that generate, sustain and reinforce racism, classism, homophobia, transphobia, and stigma (Jaiswal and Halkitis, 2019). For instance, the interaction with the health care team may look quite different for African American or white couples dealing with a chronic health condition. For we-disease, this may lead to conversations within the couple that either encourage necessary health care treatments or hinder interactions with health professionals and treatment adherence.

Furthermore, for immigrant couples, not knowing the healthcare system in the new culture and potential language barriers when interacting with medical professionals may hinder timely and effective treatment. Here, a we-disease approach may be helpful, enabling the couple to work together as a team to overcome these challenges and navigate between their own health practice expectations and those of the dominant culture. For minority couples, the experience of intersectional discrimination when interacting with the healthcare system (Leung and Ku, 2023) may lead to increased stress levels for the couple adding an additional layer to we-disease related tasks for the dyad.

Additionally, worth mentioning here are different legal situations regarding partner inclusion in medical decision making that varies between countries. In some countries, marital status is (still) a necessary prerequisite for getting medical information of the partner or being allowed into intensive care unit without patient power of attorney. These legislations may hinder we-disease in concrete ways in cases where no advance directive was deposited.

Related to culture is the couple’s socioeconomic situation and the country of residence the WDM is situated in (political system, access to healthcare). These factors will shape the resources available and thus influence the we-disease processes. Financial strain, job insecurity, and limited resources not only pose a greater risk for developing chronic illnesses later in life (Wickrama and O’Neal, 2021), but also hinder we-disease processes by increasing stress within the relationship and limiting resources and strategies for managing daily life with and treatment of the illness.

Current zeitgeist of participatory health care in western cultures encourages patients, their partners, and professionals to collaborate as partners in service delivery and treatment decision-making (Palmer et al., 2019). Another point worth mentioning regarding current zeitgeist phenomena, is the present emphasis on positive thinking visible in western health discourses and popular self-help literature. For example, the belief that positive thinking and avoiding negative thoughts are relevant for surviving cancer or illness, puts pressure on individuals to suppress negative emotional states, potentially even creating feelings of guilt if they are not successful (Aspinwall and Tedeschi, 2010). Naturally, it is important to avoid falling into the trap of promoting positive thinking only. At the same time, the principles of positive psychology and their demonstrated benefits in enhancing quality of life among individuals with serious illnesses can also be applied to couples and their we-disease processes. A shared positive focus that does not overlook or dismiss existing problems – akin to protective buffering (Coyne and Smith, 1991) – can leverage the positive aspects of this zeitgeist without negating or suppressing negative emotions.

Within other we-disease related models, historical time has been mentioned (see, for instance, Berg and Upchurch, 2007). Culture and zeitgeist may be considered as embedded in historical time. Berg and Upchurch (2007) also point to recent medical advances in treating previously fatal illnesses and the ensuing consequence that couples will deal with illnesses and treatment side effects for longer stretches of time also effecting the duration of we-disease processes.

The Trajectory Model of We-Disease (TMWD)

The WDM is mindful that for chronic health issues, we-disease is an ongoing and dynamic process, which R. F. Lyons et al. (1998) described as a “crooked path involving successive appraisal-action processes” (p. 585) which may last for years. Similar to dyadic coping processes (Berg and Upchurch, 2007), we-disease not only affects psychological and physical well-being, but is also affected by these outcomes in a cyclical, transactional nature, a “living” system that is continuously constructed and reconstructed (Karademas, 2022, p. 14). Since couples need to deal with chronic health conditions over months or even years, the maintenance of health-enhancing behaviours can play a central role for the course of the illness (Lewis et al., 2006). With the Trajectory Model of We-Disease (TMWD), we capture these complex cyclical processes over time in a schematic manner (see Figure 2).

Life phase, relationship stage and phase of illness

The TMWD is conceptually compatible with developmental psychology and lifespan-oriented perspectives (see also Berg and Upchurch, 2007). It can be assumed that the way couples deal with chronic illness or mental disorders is influenced by typical developmental tasks, role expectations, and relationship dynamics of a particular stage of life. In young couples (early adulthood), where the development of a couple identity and fostering the relationship is the central focus, chronic illness may be experienced either as a disruptive or hindering factor for the development of these processes or it may enhance them due to accelerated mutual commitment. However, as young couples only start to build their dyadic coping repertoire (Maner and Miller, 2010), it may be potentially difficult for them to engage in we-disease due to a lack of established dyadic coping strategies and a lack of well-known habits to deal with stress together (Berg et al., 2016). If the couple identity is not yet strong enough, partners may feel overwhelmed by the responsibility of shared illness management and thus may tend to see the chronic illness or disorder as an individual problem (Helgeson, 2017). It is also possible that other life plans exist, such as starting a family or going traveling, which are threatened by a partner’s chronic illness, or the couple may be less committed overall because there is not yet a shared home or a shared family that binds them together in a more serious way.

Middle-aged couples may be more ready to engage in a we-disease perspective and joint dyadic coping as their couple’s identity may be stabilized and they can draw on previous dyadic coping experiences (Berg et al., 2016). However, these couples are usually characterized by high family and professional stress or are even caring for their own parents, where we-disease would add additional strain to an already highly burdened life stage. Nevertheless, we assume that established dyadic coping patterns, shared life narratives, high mutual dependability and commitment would facilitate a we-disease perspective and invite joint dyadic coping efforts in midlife.

Elderly couples may show high openness to we-disease as illness is often experienced and a prevalent part of aging. As a result, they may be more receptive to shared stress management in the context of illness. Often, elderly couples possess a long-standing dyadic history with shared values and firm habits of dyadic coping (Berg et al., 2016) and share a mutual willingness to care for each other. However, their resources may be limited by declining strength and well-being, own illness or disabilities, and mutual co-morbidity. In addition, their social network is often reduced (Wrzus et al., 2013).

In all developmental phases, irrespective of age, it is essential to consider whether the couple is in a centripetal (closeness-seeking) or centrifugal (distance-seeking) phase, as well as the intensity of the desire for intimacy versus autonomy expressed by each partner (Baxter, 2004). However, while even in a centrifugal phase the serious illness of one partner can release centripetal forces, it is conceivable that in a symbiotic phase the illness could also tear the couple apart under the impact of this massive stress. Therefore, we believe that ultimately it is not so much the stage of the relationship (except in the case of very young couples) that is decisive, but rather the quality of the relationship and, in particular, the mutual commitment and dedication to one another (Agnew and VanderDrift, 2018).

The life stage may further interact with illness features such as illness progression, the likelihood of successful medical treatment, disruptions and periods of improvement, as well as the unpredictability of outcomes, as observed in certain types of conditions like multiple sclerosis or some forms of cancer. Whether it is a first-time illness with good prospects for recovery, a relapse, or a recurrent disease may be crucial for engagement in we-disease. Additionally, sudden unforeseen medical events, like a myocardial infarction or a stroke, bring with them their own adaptive challenges, particularly in the acute phase of the illness as described by Cornelius (2021) in the dyadic disruption theory. According to this theory, early post event stress levels of couples can precipitate harmful patient and partner dynamics like high levels of co-rumination which will cement negative psychological reactions with long-term consequences. The temporal process of coping has also been described in detail by Berg and Upchurch (2007) with specific phases like anticipatory coping, initial symptom identification, coping with treatment, and daily management.

Therefore, illness stage, life stage, and relationship stage may closely interact with each other. Taken together, these aspects influence outcomes such as individual and dyadic resilience or growth, as well as patterns of joint decline or divergence, whereby one partner may experience deterioration while the other shows improvement.

Functionality of we-disease

Typically, optimal adjustment or high patient and partner physical health and psychological well-being are considered as signs of functional joint coping (Helgeson et al., 2018). We go one step further and delineate relevant aspects that should be considered for the evaluation of we-disease functionality. Functional we-disease requires an adaptive, shared representation of illness (mutual awareness without neither pathologizing nor trivializing it), cooperation among partners and joint dyadic coping according to both partner’s capacities and resources. Exceeding these resources would be dysfunctional, thus both partners should make their respective contributions within the scope of their abilities, by finding a balance between caring/caregiving and self-assertion or self-care. Furthermore, despite the definition of the illness as a we-disease, both partners should maintain their personal identity (“the disease is part of us, but it does not define us”) and not completely neglect their own life. Despite all the difficulties and demands, a certain balance between give and take should be ensured (Lyons et al., 1998). We-disease would also be considered functional if both partners are able to recognize to a certain degree a shared sense of meaningfulness and are supported by each other in their individual growth as well as in their development as a couple.

Dysfunctional we-disease could be characterized by either (a) an overinvolvement (Helgeson et al., 2018), (b) an excessive fusion (exaggerated symbiosis, co-dependency) with the loss of personal boundaries (constant suppression of own needs) and autonomy (loss of personal space and time for oneself), or (c) an overidentification with the illness, where the illness turns into the central dyadic reality, while other domains of life fade into the background. This chronic preoccupation with the illness as a couple hinders other dyadic perspectives and experiences as a couple or as parents. Thus, if the illness becomes the defining feature of the relationship (everything revolves around it), we-disease will be drifting into a pathological direction.

On a behavioural level, following STM, we-disease becomes negative when the partners begin to engage in negative dyadic coping (uninvolved, controlling, superficial, ambivalent, hostile contributions to joint DC; Bodenmann, 2005). Also, maladaptive collaboration, like jointly engaging in unhealthy behaviours (Helgeson et al., 2018) may characterize dysfunctional we-disease. Whether a couple’s avoidance of necessary treatments due to mistrust in the medical system is deemed dysfunctional remains a subject for ongoing discussion. There is no definitive, universal answer to this question, as it requires consideration of the contextual and individual factors discussed above. Ultimately, the decision regarding treatment adherence should be left to the couple, as it cannot be objectively determined or externally prescribed. But of course, all negative outcomes in health – such as the partner, for their part, becoming ill from exhaustion, developing “burn-out” or mental health issues – reflect maladaptive aspects of prolonged we-disease engagement.

Individual/dyadic resilience and stability

Resilience is a process defined by Masten (2014) as the ability of a system to adapt successfully to disturbances, which threaten its function, viability, or development. Within the WDM, a resilient trajectory is conceptualized at both the individual and the couple level. Over the course of a chronic illness, the couple is likely to encounter challenging and stressful phases; however, through adaptive processes, they generally maintain or regain positive levels of well-being and health despite of and alongside with the ongoing presence of the chronic condition. Similarly, in the TMCC, resilience is also mentioned as an outcome alongside thriving (Afifi et al., 2020). Ungar (2018) postulates the concept of systemic resilience, where resilience is not a property of the system itself, but arises from the interaction with other systems. In the context of the WDM, this includes the interaction between the partners within the relationship but also the interaction with other systems outside the relationship.

Both partners may experience resilience, however adaptation may come with a cost and there are likely trade-offs between systems that affect each partner’s outcomes differently (Ungar, 2018). In the WDM, the opportunity of the ill partner to experience a largely unchanged daily life may come at the expense of the caregiving partner. For instance, in the case of dementia, where the partner needs to take on more and more tasks in order to maintain the couple’s daily routines and the care-receiver faces a loss of autonomy (Gellert et al., 2018). Thus, resilience needs to be considered individually as well as dyadically.

Individual/dyadic growth

Within the WDM, individual and dyadic growth is understood closely related to the concept of posttraumatic growth, which has been mostly studied in the context of traumatic stressors and is defined as positive psychological change that occurs from exposure to highly challenging life circumstances (Tedeschi and Calhoun, 2004). In the WDM, similar to Tedeschi and Calhoun (2004), trauma is understood in a broader sense, not necessarily requiring a traumatic event but rather encompassing challenging life circumstances like chronic illness or a mental disorder, which can serve as significant and ongoing stressors for the individual and the dyadic relationship. Even though some diagnoses and treatment experiences may indeed be traumatic for the patient and/or their partners. Posttraumatic growth is viewed as both an outcome as well as an ongoing process.

Growth is the experience of changes after a phase of struggling. These changes are viewed as relevant by individuals and couples that go beyond pre-trauma levels of adaptation. This could be a more intimate couple relationship, increased appreciation of life and changed priorities, an increased sense of individual or dyadic strength and spirituality (based on Tedeschi and Calhoun, 2004). The role of relational and individual growth has already been applied to the context of dyadic coping with chronic illness within the RCCM (Kayser and Acquati, 2019; Kayser et al., 2007). Additionally, in the TMCC, the concept of thriving is mentioned as an outcome of communal coping processes (Afifi et al., 2020). Thriving shares considerable overlap with posttraumatic growth and is defined by the authors as physical and psychological well-being encompassing hedonic (happiness, quality of life), social (secure and meaningful connections with others), and eudaimonic well-being (sense of purpose and meaning in life, personal growth, self-discovery).

Another concept that is fairly new to the field of psychology which supplements and expands the understanding of posttraumatic growth and is thus worth mentioning here, is antifragility, a phenomenon first described by Taleb (2012). Antifragility refers to the phenomenon that adversity, uncertainty, and randomness can be opportunities for growth and development. Thus, systems will actually strengthen and evolve through disruption (Taleb, 2012). Hence, antifragility is not a conceptualisation of the we-disease process and outcome, but rather similar to a personality trait or an attitude of an individual or a dyad that increases the probability of a personal growth outcome. In contrast to posttraumatic growth, antifragility can also take place in daily life with everyday stressors.

Individual/dyadic decline

A rigid we-appraisal, co-rumination, overstretching of resources, disregard for boundaries and individual needs, or the erosion of individual autonomy and self-efficacy, as well as protective buffering, can have negative consequences. Instead of the positive effects of we-disease, the outcome would be a deterioration of individual well-being of both the patient and their partner. With the ongoing over-identification of the couple with the illness (“everything revolves around the illness”), areas of exchange unrelated to the illness take a back seat, thus intimacy, sexuality, diversity of roles, and the pursuit of common goals (outside of the illness) may suffer. On an individual level, this can result in anxiety or depression, exhaustion and burnout (Geng et al., 2018), as well as somatic symptoms (such as high blood pressure, sleep disorders, immune deficiency; Goren et al., 2014). On a couple level, we-disease-related stress leads to tension, conflict, more negative dyadic coping, greater dissatisfaction and, in the long term, a potentially higher risk of separation.

Clinical implications

A number of clinical implications can be derived from the model; here, some key considerations are briefly outlined: To encourage and support beneficial we-disease processes for a couple, medical staff should consider the partner as an important component of the treatment to be taken into account and include them into decision making and treatment processes. Additionally, it is important to not only focus on the patient’s health but also to check in with the partner on their current situation, care burden, stress level, and need of support.

Considering the multiple factors influencing adaptive we-disease processes within the WDM and TMWD, it follows that an interdisciplinary team is required to support couples in their we-disease approach when dealing with a chronic mental or somatic health condition. This team should encompass not only the medical and nursing staff, but also nutritional counsellors, family support workers, psychologists, couple and individual psychotherapists, and religious counsellors as well.

For healthcare professionals, it is important to be aware of cultural gender role expectations and other components presented above. Finally, in light of tight health-care budgets, potential we-disease interventions need to be developed in ways that are efficient and feasible (Mendenhall et al., 2025).

From a clinical point of view, we-disease is indicated when stressors affect both partners, who share a we-appraisal, and common/joint dyadic coping is feasible for both. As a medium dose (shared goals, coordinated roles, joint dyadic coping efforts on the one hand, maintaining autonomy and self-care on the other hand) is recommended, therapists should encourage the couple to find and define the level of we-disease that is appropriate for them according to the phase of illness and in terms of skills, personal and dyadic resources, and individual motivation. In particular, therapists should work on feelings that arise both when engaging in we-disease (e.g. feelings of fear, worry, overwhelm, helplessness) and when distancing themselves from it (e.g. feelings of guilt, insufficiency, shame), and allow these feelings to surface honestly through mutual emotional self-disclosure for instance using the 3-phase method (Bodenmann and Milek, 2016). The therapist can also promote meta-communication (“What is your shared issue, what remains individual?”) and introduce short daily “we-briefings” so that they remain in regular communication about joint problem-solving and shared emotion-regulation. To achieve a healthy balance between we-disease and the individual partners, the therapist may invite the couple to illness-free time slots, where other issues are predominant (e.g., hobbies, socialize with friends, time with children, relevance of self-care, joyful joint activities) and provide a counterbalance to the constantly present severity of the illness. The therapist can also help to reduce downsides of we-disease such as protective buffering, co-rumination, overprotection, loss of independence in a benevolent, sensitizing manner. At the end-of-life phase, the therapist may support the couple discussing topics such as dignity in dying, the meaning of life, letting go and moving on, and finding an appropriate farewell ritual, and a retreat without feelings of guilt and ending of we-disease. Since this we-disease approach is unfamiliar to many therapists, training specific to we-disease should be developed and therapists should be supervised during the process.

Conclusions

With the We-Disease Model (WDM), we propose an integrative and holistic framework applicable to both mental disorders and somatic illnesses in couples. The Trajectory Model of We-Disease (TMWD), on the other hand, extends the WDM to capture the dynamic and processual nature of long-term we-disease processes, emphasizing their relevance for consideration within healthcare settings.

The WDM stresses the relevance of including the partner not only in medical and health management decisions but also checking in with the partner during medical appointments to make them feel being taken seriously and seen with their experiences.

A multitude of research questions remain unanswered within the context of we-disease. With the WDM, we aim to provide a coherent framework that can serve as a foundation for further investigation, facilitating a nuanced understanding of both the benefits and potential downsides associated with we-disease, and enabling the development of targeted interventions.

Future work should (1) test the WDM and the TMWD with longitudinal designs that identify predictors of adaptive versus maladaptive pathways; (2) use intensive longitudinal data to capture the systemic, circular dynamics of we-disease across different chronic conditions (physical and mental); (3) routinely include couple-level measures of we-disease, and (4) use appropriate dyadic statistical analysis approaches, like the Actor-Partner Interdependence Model (Cook and Kenny, 2005), the Common Fate Model, or the Dyadic Response Surface Analysis (Schönbrodt et al., 2018).

Initial tools exist to measure we-disease (e.g., the We-Disease Questionnaire; Vogt et al., 2024) and related constructs such as common/joint dyadic coping or dyadic efficacy in cancer (see for an overview Weitkamp and Bodenmann, submitted), but a comprehensive, multi-facet WDM instrument is still needed. Foundational work should delineate downsides of we-disease and identify predictors of growth (rather than depletion) at the individual and couple level. Finally, research needs to address diversity (e.g., culture, sexual orientation, intersectional identities) and examine non-partner constellations (e.g., relatives, friends, adult children) to test whether we-disease processes generalize beyond intimate relationships.

ORCID iD

Katharina Weitkamp https://orcid.org/0000-0002-0233-9177

Ethical considerations

Ethics approval was not necessary because this study is conceptual in nature and did not involve human participants.

Consent to participate

Informed consent was not required because this study is conceptual in nature and did not involve human participants.

Consent for publication

No third-party materials were used in this study. Therefore, consent for publication is not required.

Data Availability Statement

The authors did not collect any data for this theoretical paper.*