Developing Explanatory Models for Life Course Shifts in the Burden of Substance Use to Inform Future Policy and Practice

Abstract

Past approaches to policy and practice for substance use have focused heavily on young people, but recent trends indicate this approach may not be where the future lies. The crises with escalating overdose mortality in several countries, particularly overdoses related to opioids, have drawn attention to life course shifts in the burdens of substance use. Overdose mortality rates for individuals in midlife have considerably outpaced those of adolescents and individuals in early adulthood. These diverging life course trends are occurring not only in the United States, but in other countries with growing overdose problems as well. The future of effective policy and practice depend upon evidence and analyses that adapt to emerging data on shifting life course trends in drug related mortality. Within this manuscript, we consider a range of theoretical possibilities on the divergence of midlife drug mortality trends from those of young people for the purpose of outlining an agenda for future research and practice. Specifically, we consider the following theoretical approaches to move research forward in this area: Changes in Medical Context hypothesis; Emergent Comorbidities hypothesis; Cohort hypothesis; Generational Forgetting hypothesis; Legal Regulation hypothesis; Strength of Life Course Bonds hypothesis; Deepening Inequality hypothesis; Measurement Reliability hypothesis. These theoretical frameworks attend specifically to the overdose crisis but extend to other aspects of substance use. Beyond setting an agenda for research by providing empirically verifiable hypotheses, this manuscript also identifies future directions in policy and practice that are attentive to life course trends.

Introduction: The Overdose Crisis and the Life Course

There have been notable transformations in substance use trends during the 21^st century, making understandings of future drug trends less reliable based upon prior information. Past approaches in policy and practice for substance use have focused heavily on young people, but recent trends indicate that this approach may not be where the future lies. In particular, the overdose crisis has drawn attention to significant midlife mortality attributable to drug use. During the 21^st century, rates of overdose among midlife adults have escalated considerably and far exceeded those for young people. Some scholars have identified that this midlife mortality shift has contributed to an overall decline in life expectancies in certain countries, such as the United States (Acciai & Firebaugh, 2017; Dowell et al. 2017; Imtiaz et al. 2018). Within the U.S., drug overdoses now account for more deaths each year than motor vehicle accidents (Hedegaard et al. 2015; Jones et al. 2015; Rudd et al. 2016). Yet, these patterns of overdose mortality do not cohere with surveillance data on past-year and past-month patterns of use, which have continued to reflect the highest prevalence of illicit drug use and prescription drug misuse among young adults ages 18 to 25 (SAMHSA, 2019). Deeper investigations into the life course processes related to the social production of patterns of overdose remain critical for the purpose of future resource allocation in the prevention of and intervention on overdoses. While we use case material from the United States where the overdose crisis has been particularly acute, these considerations of midlife mortality attributable to overdose apply elsewhere.

The crises with escalating overdose mortality in several countries, particularly overdoses related to opioids, have drawn attention to life course shifts in the burden of substance use. Although there is evidence that overdose mortality has been escalating broadly and in an exponential fashion for the past four decades (Jalal et al., 2018), a primary period of overdose crisis has been identified from 2000 to the present. As shown in Figure 1, opioid overdose mortality rates for U.S. individuals in their 30s, 40s, and 50s have outpaced those of adolescents (12-17) and individuals in early adulthood (18-29) during the course of the overdose crisis. These diverging life course trends are occurring not only in the United States, but in other countries with opioid overdose problems, such as Australia and Canada, as well. Yet, opioids are not the only substances for which midlife escalation in overdoses have occurred. Overdoses and related adverse outcomes from other prescription medications, such as benzodiazepines and stimulants, have also escalated (Bachhuber et al. 2016; Scholl et al. 2019), as have overdoses related to cocaine and methamphetamine. Figures 2, 3, and 4 highlight the more recent growth in cocaine overdose mortality (with two peaks a decade apart), psychostimulant (which includes methamphetamine and prescription stimulants) overdose mortality, and benzodiazepine overdose mortality. These figures demonstrate the same type of escalation for middle aged adults that exceeds growth in mortality for younger people across a range of substances. As such, there is a great need to consider that past approaches to prevention and intervention in substance use may not hold for future efforts to reduce drug-related mortality.

Figure 1: United States opioid overdose rates by age and year.

Source: CDC WONDER Multiple Causes of Death data query

Figure 2: United States cocaine overdose rates by age and year.

Source: CDC WONDER Multiple Causes of Death data query

Figure 3: United States psychostimulant overdose rates by age and year.

Source: CDC WONDER Multiple Causes of Death data query

Figure 4: United States benzodiazepine overdose rates by age and year.

Source: CDC WONDER Multiple Causes of Death data query

As noted above, growth in midlife overdose mortality is somewhat of a paradox as early adulthood remains the period of the life course in which individuals are most likely to report past-month or past-year substance use. Data from the National Survey on Drug Use and Health (NSDUH) indicate that the period of young adulthood is persistently the period of the highest prevalence of drug use. As an example, Figure 5 demonstrates this trend with past-year prescription opioid misuse (we note that misuse among adolescents has recently dipped below those aged 35-64) as well as past-year cocaine use. These general life course patterns are remarkably consistent across a variety of other drugs during the entire period of observation. In this manner, we may consider that the major escalation of overdose mortality among midlife adults in the 21^st century is not attributable merely to population patterns of recent prevalence of use. Rather, there are phenomena that require additional consideration in order to reduce midlife mortality in the future.

Figure 5: United States prevalence of past year prescription opioid misuse and cocaine use by age across time.

Source: National Survey on Drug Use and Health

Life Course Explanations for the Growth in Midlife Overdose

The future of effective policy and practice depend upon evidence and analyses that adjust to emerging data on shifting life course trends. Within this manuscript, we consider a range of theoretical possibilities on the divergence of midlife drug mortality trends from those of young people for the purpose of outlining an agenda for future research and practice. While some of these issues may be effectively tended to in the near term, others involve macro-structural factors that may be less readily subject to interventions yet will remain concerns for the future. We detail each hypothesis below prior to returning to a synthetic overview of the problem and solutions for the future.

Changes in Medical Context hypothesis

Patterns of opioid prescribing have a well-documented association with overdose mortality (Bonhert et al., 2011). A focus on the supply of pharmaceutical opioids and sedatives has been emphasized as a key factor related to the growth in overdose, one which has sometimes centered attention on unscrupulous pursuit of growth by pharmaceutical companies. Yet, less attention has been focused on other changes in the contexts of medicine and clinical encounters that have enabled some of these shifts in prescribing as well as impact who receives medication and how the use of medication becomes normalized across the population. Changes in medical contexts may have had a particularly pernicious effect on midlife adults. Indeed, growth in prescribing pain medications are in response to patient experiences with pain, particularly those within middle age. During the 21st century, there has been an increase in the experience of pain and lower self-rated health among midlife adults (Case & Deaton, 2015), and these clinical reports came at a time when the institution of medicine placed greater emphasis on the treatment of pain (Walid et al, 2008). Put simply, midlife patients have increased their report of pain symptoms in observational surveys at a time when the institution of medicine was drawing attention to pain as a “fifth vital sign” and responding with prescriptions for medication. These institutional changes may have been exacerbated by increases in somatic illness during midlife, as well as midlife experiences of occupational injury and illness. As such, these factors indicate a need to move beyond overly reductionist explanations of pharmaceutical companies as bad actors (though indeed there are cases where they may be) and towards considerations of shifts in medical contexts that may have come precisely at a time when morbidities related to the prescribing and consumption of pharmaceuticals were increasing. These shifts may have had their greatest impact on access to medications and normalization of regular medication consumption among middle aged adults.

Social scientists have also identified a shift in medical authority in recent decades. Although confidence in medical doctors remains high among the general public, physicians have less control over various aspects of clinical practice (Pescosolido et al, 2001). Some of this authority has been ceded as a result of broader shifts in the healthcare system that created a system of bureaucratic and managerial control (Freidson 1994). Working within these systems, physicians have less autonomy over clinical decision making and less control over their time during clinical practice. Such shifts in medical authority may have particularly acute ramifications for adults reaching a stage when the body begins to “fail” as this may have affected treatment of patients within certain age groups more so than others. In particular, the management of symptoms such as pain, anxiety, and sleep disturbances, commonly experienced by midlife adults, within a medical context of managed care and bureaucratic demands may be more readily treated via prescriptions than with alternative methods that may demand greater physician time (Weiner et al., 1991). Such scenarios set up middle aged adults in particular for wider use of medications that may generate dependence and overdose, and potentially fuel transitions to related illicit substances.

Alongside the growth of bureaucratic managerial control over the practice of medicine, recent decades have also seen the expansion of patient consumerism. Patients anticipate greater participation in clinical decision making now, and are more apt to request pharmaceuticals for the experience of symptoms. The emergence of direct-to-consumer advertising has enhanced patient consumerism and exacerbated requests for prescriptions (Wang & Kesselheim, 2013). Within the context of bureaucratized medicine and increases in patients’ active engagement in clinical decision making, the expression of need related to symptoms can lead to clinical interactions where physicians claim it is “easier to write a prescription” (Moloney, 2017). These processes may be particularly acute for midlife adults, especially those with the cultural health capital to negotiate effectively within the context of clinical interactions (Rubin et al, 2018).

On the whole, there have been a series of changes to the context of medicine and clinical encounters, beyond those described above, that led up to and ran through the growth of drug overdoses. These shifts in medical context normalized routine medication consumption for doctors and patients alike. These shifts may have been particularly important in the initial wave of overdose deaths attributable to prescription drugs and related transitions to heroin use by some in more recent waves (Ciccarone 2019). Importantly, they are the types of changes that may be more likely to affect midlife adults as they engage increasingly with the healthcare system during a period of the life course when chronic diseases and occupational injury and illness emerge. These changes to medical contexts may have unique effects for midlife adults with respect to substance use and overdose mortality. These issues are compounded by shifts in medical contexts allowing for an increase in multiple medications among middle aged adults, with the presence of multiple medications within the body (either intentional or unintentional polydrug use) in turn escalating overdose risk. In other words, these shifts in medical contexts also facilitated prescribing for multiple conditions experienced in midlife potentially escalating fatal overdose because of interactions between substances.

Emergent Comorbidities hypothesis

As indicated above, an additional consideration is that midlife adults may be experiencing physiological changes and the emergence of chronic health problems that reduce the probability of surviving an overdose event should one occur. Put differently, younger adults may have fewer co-occurring ailments that facilitate overdose and exacerbate the likelihood of death should an overdose occur. This difference may contribute to an age-based stratification of overdose mortality that reflects higher death rates for midlife adults even if their overall rate of overdose among people across age groups who use drugs differs little from that of younger adults. In this manner, midlife adults may be less physiologically prepared to survive an overdose than younger persons who consume drugs in the same way.

Health problems, such as diabetes, heart disease, and obesity to name a few, become more emergent in midlife. These may create underlying conditions that make it less probable that an individual survives an overdose when it occurs. For example, individuals with diabetes may experience diabetic ketoacidosis that exacerbates drug related toxicity and ultimately potentially leading to poor survival outcomes when an overdose occurs (Byard et al., 2006). The prevalence of diabetes among adults between the ages of 30 and 60 increased considerably from the early 1990s through the late 2000s (Cheng et al., 2013), meaning that a greater proportion of midlife adults has a chronic condition that elevates the probability of a fatal outcome. Obesity-related impairments to respiration occur as body mass increases (Malhotra & Hillman, 2008) and these may enhance the probability of an opioid overdose occurring and reduce survivability should such an overdose occur. The increase in obesity within the U.S. over the past several decades, particularly among midlife adults, has been well documented (Fryar et al., 2012). Similarly, cardiac problems emerging in middle age may not only lead to the increased likelihood of a drug-related cardiac event, but also may create circulatory impairments that inhibit the potential to survive an overdose related to respiration. Furthermore, there is a socioeconomic stratification to these comorbid physiological risk factors that mirrors the stratification of overdose patterns, which may intensify as individuals age into midlife. Additionally, research has indicated that socioeconomic inequalities in the prevalence of psychological distress, which may produce adverse coping with substances, reach a peak during midlife (Lang et al., 2011).

Although uncertainty currently exists at the time of this writing, the novel coronavirus - COVID-19 - could also play a role in the emergent comorbidities hypothesis. The comorbidities that increase risk of overdose, such as coronary heart disease (resulting from obesity), hypertension, and diabetes are hypothesized risk factors for COVID-19 mortality (Zhou et al. 2020; Wu and McGoogan 2020). Further, respiratory suppression represents the underlying physiological cause of an opioid overdose (White & Irvine 1999), the very response that also contributes to deaths from COVID-19. Thus, the emergence of this pandemic – as well as the possibility of future infectious disease outbreaks that affect pulmonary health – could contribute to the interplay of comorbidities for midlife fatal overdose.

Cohort hypothesis

Another potential consideration is that the shift in midlife mortality associated with current trends in drug overdose may be the result of a cohort effect. Cohorts – often popularly conceived of as generations – can display varied patterns of behavior at similar ages in the life course. Importantly, experiencing a certain stage of the life course in particular historical moments can inscribe certain characteristics and views upon a cohort (Elder, 1975). For example, the experience of childhood during the Great Depression had a lasting effect on the attitudes, tastes, and values of this cohort, and such experiences played a key differentiating role between this cohort and the cohort of Baby Boomers born into a period of major economic growth and general prosperity (Elder, 1999). In this manner, cohorts can be conditioned by their experiences of the world in particular moment in ways that shape attitudes, norms, and behaviors.

A component of the ebb and flow of drug trends over time is the role of cohorts. Given the unique historical circumstances that shape aging through the life course in a particular moment, cohorts can have distinct experiences of social norms related to drug use (Keyes et al., 2011) as well as varied patterns of drug use, even for substances that remain common over time, such as marijuana (Miech & Koester, 2012). Temporal patterns of substance use during one period of the life course, e.g. adolescence, can shape how drugs are perceived and used at later period of time. As such, the diffusion of a drug trend at a particular time may result from a specific cohort driving the effect.

The most straightforward manner in which cohort effects lead to differential growth in overdose mortality is through membership in a high substance-using teenage and young adult cohort. For example, members of U.S. youth cohorts in the 1980s experienced particularly high rates of powder and crack cocaine and marijuana use (Miech et al 2017). In the early 1990s, by contrast, use of most classes of substances declined among high schoolers. Although pop culture suggested heroin use through grunge subcultures and the “heroin chic” trend in fashion – both popularized from 1991 to 1993 – epidemiological surveillance systems indicate heroin use and other “hard drugs” among adolescents and young adults experienced a low during this period and did not begin rising until later in the 1990s (Miech et al 2017; SAMHSA, 1999). Indeed, the late 1990s saw peaks in heroin, MDMA, marijuana, and LSD use, all of which subsequently declined across the 2000s to current historical lows among adolescents (Miech et al 2017). Thus, although there was a brief period of low use cohorts in the early 1990s, most of the cohorts currently experiencing midlife overdoses reported particularly high levels substance use compared to recent cohorts of young people, which affected patterns of use related to perceived risk among middle aged adults more recently in a way that has shaped patterns of overdose mortality as they transitioned into midlife.

Generational Forgetting hypothesis

We may also consider that the impact of substance use trends may be a function of “generational forgetting” – a factor that may both highlight and belie the role of a cohort effect. The concept of generational forgetting considers that drugs may re-emerge in later periods when new generations of people “discover” these substances anew with no experiences or memories of the prior period of their use and the negative problems associated with this use (Miech et al, 2017; Patrick & O’Malley, 2015). For example, Monitoring the Future shows a nearly mirror image of use of marijuana and perceived risk of marijuana over time, until the most recent years (Miech, Johnston, & O’Malley, 2017; Miech et al. 2017:437). The reemergence of LSD during the 1990s, long after its initial wave of popularity during the 1960s had faded, also is a noted example of this phenomenon (Chilcoat & Schutz, 1996; Gold & Gleaton, 1994). The wave of overdoses that have escalated in many countries may be in part due to middle aged adults having been born during or after the heroin trend of the 1960s and 1970s. While heroin use no doubt persisted in many countries, it remained endemic at low levels rather than of “epidemic” scale covered by the media and discussed by politicians; this lack of visibility as other drug trends took precedence contributes to generational forgetting.

Beyond the generational forgetting of specific drugs, there may be a different type of generational forgetting regarding the impact of drug trends more generally. Although conceptualizations of generational forgetting typically focus on the effect of cohort replacement with younger generations unfamiliar with the problems associated with specific past drug trends (Miech et al, 2017; Patrick & O’Malley, 2015), we contend that a tendency to focus on youth and individual drugs in media representations and political discussions (Ritter and Bammer 2010; Lancaster et al 2011; Hughes, Lancaster, & Spicer 2011) as well as prevention and intervention efforts may also lead to a generational forgetting of prior drug trends in a generalized sense. In other words, cohorts forget as they age through middle age. These may be exacerbated as social roles shift across the life course, and as individuals age into midlife and away from the conceptualization of harms tied to their social lives as young people, the impact of drug trends may not be felt in the same way. As such, there may be a within-generation forgetting in addition to a between-generation forgetting.

As noted above, the current generation of middle aged adults “missed” the major heroin trend of the 1960s and 1970s and a subset were exposed to the brief heroin trend of the late 1990s; this shaped a lacking firsthand knowledge of a prior opioid crisis and could have contributed to between-generational forgetting. Considering within-generational forgetting in the context of the most recent drug trend related to opioids, middle aged adults may have disregarded the impact of prior drug trends, such as the crack cocaine trend (Reinarman and Levine 1989; Hartman and Golub 1999), on population health in part because the norms, messaging, and contexts associated with past trends remained specific to a certain drug and were not readily applied to prescription drugs and the wider opioid trend. The distance from their adolescent experiences of drug prevention education may exacerbate the problem, particularly among midlife adults who perceived that they escaped the heightened risks of adolescence and early adulthood.

Legal Regulation hypothesis

Broader shifts in the legal regulation of substances may have had a spillover effect on patterns of drug use that impact overdose mortality among midlife adults. The 21^st century has seen increasing expansion of cannabis policy, whether via medicinal or recreational pathways (Kilmer and MacCoun 2017). In addition, renewed interest in the use of psychedelics for therapeutic purposes has begun to shift popular perceptions of other types of psychoactive drugs (Nichols, Johnson, & Nichols 2017). The reconsideration of these substances, particularly for therapeutic purposes, may broadly relate to shifts in acceptability regarding drug consumption. As midlife adults may be particularly interested in the medicinal effects of these substances, they may be more inclined to a reassessment of norms and attitudes surrounding drug use more broadly.

The shifts in broader norms about psychoactive substances across the population may have a large impact on midlife adults, as this has tended to be a period of the life course where social roles constrain against the use of substances. Midlife adults typically experience reduced substance use during these years in part because network ties to illegal substances dissipate with life course transitions as individuals age (Warr 1998). In this manner, not only do individuals aging into midlife have fewer network ties supportive of substance use, but also fewer direct connections to drug markets as changes in networks reshape access to drugs. However, legalization of other previously illegal drugs changes this access, which in turn may reinvigorate former patterns of substance use and reshape markets in particular ways. In other words, changes in legal regulation may alter midlife adults’ norms and network access to drug markets more broadly in a way that they have not for younger adults. While social roles may have previously provided a constraint prior to regulatory shifts, the roles themselves have also changed (see related life course bonds hypothesis below).

The return to substance use engendered by policy shifts in legal regulation may have particularly unique effects among midlife adults. Having “matured out” of substance use as they aged into adult social roles (Moffitt 1993), they may have dampened perceptions of risk associated with their youthful substance use in ways that have consequences as they return to substance use later in life. They also have temporal distance from the prevention messaging of their youth that may shape risk perceptions in returns to substance use. As such, the policy contexts that may enable a return to drug use in midlife may also lead to a return ill-equipped for contemporary risks.

Strength of Life Course Bonds hypothesis

A central theoretical concept in criminological life course theory is that the presence, strength, and quality of bonds to social institutions prevents or reduces participation in deviance and crime (Laub & Sampson, 2003). Particularly in adulthood, bonds via employment and marriage produce a stake in conventional institutions and responsibilities that steer adults away from behavior such as substance use (Laub & Sampson, 2003). At the same time, these bonds also draw adults away from their peer networks with whom substance use may be more likely (Warr 1998). However, individuals of adult age during the overdose crisis experienced economic and demographic shifts that may have undermined these bonds.

Beginning with employment, there is robust evidence that employment and labor market participation is associated with lower odds of substance use (Compton et al., 2014; DeSimone, 2002; French, Roebuck, & Alexandre, 2001). For those of working age, the Great Recession resulted in the greatest loss of employment and wealth since the Great Depression (Carruthers & Kim, 2011), and the relationship of employment to substance use remained strong during this period (Compton et al., 2014). However, some individuals suffered great losses, while others remained unharmed (Grusky, Western, & Wimer, 2011). While those with college degrees were more likely to remain employed, those without college degrees saw a large reduction in employment (Vuolo, Mortimer, & Staff, 2016). For those searching for jobs with no required experience, the odds of obtaining employment dropped considerably (Vuolo, Uggen, & Lageson, 2017). Thus, those of low socioeconomic attainment came out on the bottom. Despite common rhetoric surrounding the opioid crisis that opioids affect all, mortality is much higher and increased more dramatically among those with low education, as demonstrated by Figure 6. As those of low socioeconomic status suffered most during the Great Recession, these trends lend themselves to the hypothesis that changes in employment bonds and the inability to acquire new stable employment may have contributed to the specific increases among those of working age.

Figure 6: United States age-adjusted overdose rates by education and year.

Source: CDC restricted access mortality data

Marriage also represents a critical bond that reduces the odds of substance use, especially in those who feel a strong attachment to their partner (Heinz et al., 2009; Duncan, Wilkerson, & England 2006; Merline et al., 2004). The delay of marriage provides increased time to associate with delinquent peers (Warr 1998). Further, the effect of marriage on substance use is stronger than that of cohabitation (Duncan et al., 2006). Finally, divorce results in increased substance use patterns (Yamaguchi & Kandel 1997). However, recent cohorts have been delaying entry into marriage, often substituting periods of cohabitation (Mernitz 2018). While divorce rates increased through the 1980s, they stabilized among those with college degrees but continued to rise for those with lower levels of education (Martin 2006). Similar to employment then, trends in the bonds to marriage at the population level may have affected mortality and dependence among midlife adults whose experiences shifted with these demographic trends.

Deepening Inequality hypothesis

Socioeconomic inequality has had a durable relationship with population health (Wilkinson & Pickett, 2006; Pickett & Wilkinson, 2015). According to recent U.S. Census data, inequality as measured by the GINI coefficient has recently reached its highest point since the issue has been tracked (U.S. Census, 2020). A measure of wealth distribution with zero indicating perfect equality and 1 indicating perfect inequality, the GINI index has grown from 0.394 in 1970 (the birth-year of individuals currently age 50) to 0.486 in 2018 (the most recent year for which data are available; U.S. Census Bureau, 2020), indicating that inequality has become more extreme within the United States over this period. In addition to recessionary effects described above, the growth of inequality within the United States has accelerated during the 21^st century and this may have had particularly adverse effects on the middle aged. As they referenced the relative prosperity of the cohort aging in front of them (the Baby Boomers), they may have experienced relative deprivation (Smith et al., 2012), ultimately shaping drug use, morbidity, and mortality (Wilkinson & Pickett, 2007; Subramaniyam et al., 2009). As noted above, psychological distress also peaks during midlife (Lang et al., 2011). As such, the growth in inequality may be affecting midlife adults particularly hard.

The impact of increasing inequality and related distress in midlife can potentially drive patterns of substance use during this period of the life course. Research has suggested that there is an inverse relationship between socioeconomic status and heavy substance use (Katikireddi et al., 2017; Turner & Lloyd, 2003) and that particular behaviors, such as injection drug use, may be associated with contexts of income inequality and related forms of residential segregation (Friedman et al., 2016; Karriker-Jaffe, 2013). At the neighborhood level, income inequality can be a major risk factor for fatal overdose (Galea et al., 2003), which provides an empirical basis for considerations that deepening inequality may directly affect overdose mortality in midlife.

Deepening patterns of within-society inequality may exacerbate drug dependence and subsequent mortality. These experiences of deepening inequality may be felt most for midlife adults, who are sandwiched between responsibilities of raising children and caring for aging parents. Consequently, although they may be less likely than younger adults to casually use or experiment with drugs that can lead to fatal overdose, they may experience greater patterns of harmful use as a result of inequality-related distress. Driven by how inequality is experienced in midlife, such patterns of use may result in the higher rates of overdose mortality that emerge in midlife.

Measurement Reliability hypothesis

A final question remains whether measurement reliability has shifted during the past two decades in a way that highlights midlife mortality related to drugs. This measurement reliability may pertain either to the measurement of mortality itself, which may more accurately reflect midlife drug-related mortality than in the past, or measurement of self-report data on substance use in midlife, which may have previously underestimated drug use as individuals age through the life course beyond early adulthood.

Mortality data quality for drug overdose has varied over time and this variation may affect estimates of overdose mortality (Buchanich et al. 2018). Put simply, the identification of drug-related causes of death have become more precise over the course of the overdose crisis. As greater attention has been placed on the escalation of drug related mortality during the 21^st century, surveillance of mortality may have become more refined, and the attention of medical examiners to this cause of death may have been better focused. This greater precision may reduce the possibility of undercounting midlife mortality attributable to drugs, some of which previously may have been attributed to other causes of death.

Additionally, we may have been previously underestimating substance use among midlife adults, further fueling an earlier misrecognition of overdose mortality. As noted above, the use of substances becomes less normative as individuals age out of early adulthood into midlife. As argued by Massoglia and Uggen (2010), behaviors such as substance use are perceived to be more appropriate at certain stages of life (adolescence, emerging adulthood) than others (middle adulthood). As such, a self-recognition occurs regarding the age-inappropriateness of certain behaviors, including substance use, as individuals make the transition into adulthood. Individuals internalize the appraisals of others and attempt to signal having achieved adulthood by ceasing these behaviors. Thus, desistance of substance use is not merely predictive of but a constituent component of adulthood (Massoglia and Uggen, 2010). Yet, these same processes of internalization that inhibit the use of substances, also likely inhibit the reporting of substance use among midlife adults. In other words, young people – for whom substance use is more normative and age-appropriate – have fewer inhibitions in the self-report of drug use in comparison with midlife adults, especially since substance use may be viewed as incompatible with midlife social roles, e.g. parenthood, workplace supervision. Altogether, this may have contributed to under-recognition of drug overdose mortality in midlife until this problem captured the popular attention.

Multifactorial Influence

Importantly, we must consider that it may be no single hypothesis identified above that has resulted in the shifts in drug-related mortality curves across age groups. Rather, the intersection of several of these dynamics may have fomented a multifactorial problem. Complex patterns of morbidity and mortality, especially those dependent upon human behavior, rarely have a singular explanatory mechanism. Modeling procedures that allow for the integration of multidimensional causes may best facilitate future directions for prevention and intervention. Further, as suggested by the increasing inequality hypothesis, consideration of syndemic processes (Singer, 2000) connected to elevated overdose mortality among midlife adults would be worth pursuing.

Discussion: How Life Course Explanations Shape Addiction Futures

The Future of Policy, Prevention, and Intervention

This paper highlights the exacerbation of midlife mortality attributable to drug overdose. We have offered several conceptual frameworks to consider why this escalation of overdose mortality was so fully situated in middle age. These theoretical frameworks attend specifically to the overdose crisis but extend to other aspects of substance use relevant to midlife adults. A comprehensive sociomedical approach may help to identify a means of disrupting these trends to facilitate future health, particularly as midlife adults age into later life. While we offer numerous conceptualizations on the growth of midlife overdose mortality for future testing, as we note above, we contend that this is likely a multifactorial problem that is not reducible to a single issue. Beyond setting an agenda for research by providing conceptualizations for empirical study, below we also identify future directions in policy and practice that are attentive to these life course trends.

Foremost, we call attention to the future need to more explicitly address the potential for harm in substance use during midlife. Many approaches to prevention and intervention heavily focus on young people. While young people may be the group who report the highest prevalence of past year use of drugs, future efforts must work towards addressing issues related to drug use and overdose that may be unique to midlife adults. In these future efforts, wider awareness among the population of the problems attributable to midlife substance use may also heighten attention to this issue, facilitate linkages to treatment, and reduce stigma among midlife adults that may heighten the probability of poor outcomes.

Within Table 1, we outline a series of recommendations for the future direction of prevention, intervention, and policy. Each hypothesis posits a different mechanism by which midlife overdose has increased, and thus we list future possible foci should a given mechanism be confirmed by empirical research. We recognize that many of these recommendations are challenging to implement, and are not currently supported across the political spectrum. However, a public health crisis such as fatal overdoses requires forethought into what future solutions, if put into place, would address these issues and prevent future harm. Thus, these recommendations follow the spirit of futuring by envisioning what strategies, if fully realized at some future point, could neutralize certain mechanisms causing midlife overdose that exist in the present. We describe them in order of presentation above.

Table 1:

Summary of hypotheses, mechanisms, and future policy, prevention, and intervention foci

Hypothesis	Mechanism increasing midlife overdoses	Future foci if mechanism confirmed
Changes in medical context	Trends in prescribing, reductions in physician autonomy, patient consumerism, and bureaucratization of medical practice may increase use and dependence	Emphasize and reward preventative medicine; increase physician autonomy and authority; create policies for appropriate prescribing practices of controlled substances; enable alternatives to medication
Emergent comorbidities	Comorbidities exacerbate consequences of substance use, with harms of both use and comorbidities rising	Programs to address comorbidities such as obesity and diabetes; discussions of risks of substance use when comorbidity identified
Cohort	High substance-using teenage cohorts carry increased risk with them through life, while low risk cohorts may carry low perceived risk forward	Increased addiction screening among high risk cohorts at points-of-contact with healthcare. Continued prevention education among cohorts with low risk early experiences.
Generational forgetting	Perceived risks wane as use decreases, resulting in reemergence of use	Drug prevention and education addresses all substances and ages, regardless of current fads and trends
Legal regulation	Liberalization of drug policies have allowed those in midlife to rediscover substance use	Create opportunities to provide prevention information about more harmful substances. Harm reduction and addiction services information at legal points-of-sale.
Strength of life course bonds	Market forces and demographic trends have decreased the chances of quality bonds to employment and marriage	Market regulation and disaster planning to prevent recessions; links between drug treatment system and others such as unemployment system and divorce courts
Deepening inequality	Wages and wealth have become increasingly stratified, exacerbating use	Investment in social welfare programs; Income redistribution
Measurement reliability	Changes in rates are reflective of better (or worse) measurement quality	Develop national and international conventions regarding measurement of overdose causes of death and self-reported substance use

Regarding the changes in medical contexts hypothesis, trends in prescribing patterns, reductions in physician autonomy, patient consumerism, and bureaucratization of medical practice may have inadvertently shaped increases in the misuse of prescription drugs and dependence on medications, which may have disproportionately affected midlife adults. Future state and institutional policy approaches that emphasize and reward preventative medicine, facilitate physician autonomy and authority where needed, create policies for appropriate prescribing practices of controlled substances, and enable alternatives to psychoactive medications may have a sustained impact on future reductions in use of medications that may produce fatal overdose, especially among midlife adults who experience increasing health issues during this period of the life course, particularly if managed with multiple medications.

Regarding the emergent comorbidities hypothesis, the presence of midlife comorbidities may exacerbate the consequences of substance use, with harms both from substance use and from comorbidities rising. Programs to address comorbidities among midlife adults, such as obesity and diabetes, should be more widely implemented in the future as they may impact morbidity and mortality related to substance use. Discussions of heightened risks of substance use when a comorbidity is identified with a person can also be carried out in diverse settings, from the doctor-patient interaction to services offered by harm reduction organizations. Additionally, if we incorrectly assume that drug overdose mortality disproportionately affects young people, then substance abuse treatment and mortality might be left out of discussions of COVID-19 risk factors and those of possible future pandemics. Thus, we encourage future research and discussions of the link between comorbid sources of death as well as broad efforts to reduce co-morbid conditions within the population.

Regarding the cohort hypothesis, heavy substance-using adolescent cohorts may carry increased risk with them as they age through life. Future intervention work among adults should focus on additional screening for drug dependence among high risk cohorts at points-of-contact with healthcare, and re-screenings as such cohorts age through the life course. For cohorts with low risk early experiences, future prevention efforts should focus on continued prevention education as these individuals age into midlife, since shifts in drug trends may create new challenges for cohorts experiencing low levels of substance use in their younger years.

Regarding the generational forgetting hypothesis, perceived risks tend to wane as a drug trend dissipates, resulting in reemergence of use among later groups, as well as the potential for within-generation forgetting, whereby a cohort was aware of prior risks but these perceptions of risk fade as these individuals age into midlife. Future drug prevention and education efforts should address many substances across periods of the life course, regardless of current fads and trends. Midlife adults may also benefit from “continuing education” through prevention efforts geared towards their midlife experiences. Such continuing education efforts targeting midlife adults may inhibit the emergence of or reduce the peak of future drug mortality trends.

Regarding the legal regulation hypothesis, the liberalization of drug policies may have allowed those in midlife to rediscover substance use. Yet, these legal markets also may create future opportunities as sites for the distribution of prevention information about more harmful substances. Additionally, these businesses can provide information about local harm reduction agencies and addiction services at these legal points-of-sale. Future growth of legalized drug markets must involve the promotion of health and harm reduction efforts not merely to reduce harms from these substances but also those related to their combined use with other substances that remain illicit, including medications used beyond the scope of a doctor’s prescription.

Regarding the strength of life course bonds, market forces and demographic trends may have decreased the chances of quality bonds to social institutions that tend to inhibit substance use, such as employment and marriage. Future efforts to reduce unemployment such as market regulation and disaster and pandemic planning of emergency stimulus packages to prevent and address recessions may provide a foundation to address many underlying issues, including economic factors that may lead young adults to delay marriage and parenthood. The creation of links between the drug treatment system and the workplace as well as to unemployment systems and divorce courts may facilitate the prevention of harms within the context of these institutions in the future.

Regarding the deepening inequality hypothesis, wages and wealth have become increasingly stratified, potentially resulting in the exacerbation of substance use. To prevent future problems, efforts to address macro-structural inequities through investment in social welfare programs, shoring up safety nets, and income redistribution must be considered. Such changes are challenging to move forward, but such upstream factors may well have a wide effect on a range of health problems and mortality.

Lastly, the measurement reliability hypothesis considers that life course stratification may reflect changes in levels of better (or worse) measurement quality. Future policies that work towards the development of national and international conventions regarding measurement of overdose causes of death and self-reported substance use, as well as funding for their wide implementation, may prevent future disruptions and more accurate long-term measurement.

Future Implications for Cohorts of Young People and Current Midlife Individuals

The mechanisms identified by each hypothesis allow us to speculate about future trends for more recent cohorts of young people to consider how they might also experience high midlife overdose mortality and what might prevent such trends from continuing. It is notable that the most recent cohort of adolescents in high school from 2015-2018 have experienced some of the lowest levels of illicit substance use among adolescents in several decades. Ensuring that future experiences promote health and well-being as they age into midlife is essential. In recent years, the medical context in the U.S. has changed for cohorts of young people in ways that could benefit midlife overdose trends in the future. The Affordable Care Act increased health insurance coverage, especially for young people via extending dependent coverage until age 25 and the individual mandate, while also rewarding preventative medicine (Sommers and Kronick 2012). At the same time, policies such as prescription drug monitoring programs have been adopted more widely and strengthened to reduce non-essential access to controlled substances (Smith et al. 2019). However, as childhood obesity rates have remained high in the U.S. (Ludwig 2018), current young people may be at increased risk for comorbidities of overdose, emphasizing the need for policies and health promotion strategies that directly address obesity as well as the prevalence of health conditions resulting from obesity.

As noted above, for recent cohorts, the use of psychoactive substances are at the lowest prevalence levels in generations, which could translate into future low prevalence of problematic substance use. Future considerations of how these young people approached substance use as teenagers may shape population-level and individual-level interventions as drug trends continue to shift over time as they age. However, if such downward trends are sustained, new cohorts may experience generational forgetting and could neglect the risks of drugs with overdose liability, which could lead to future resurgence. Furthermore, the legal landscape of substances, particularly for cannabis, will likely continue to change, and young people may respond to an entire adulthood with legal access differently than older cohorts who experienced prohibitions. These possibilities point to the need for distinguishing risks and norms between cannabis and more harmful substances to ensure that patterns of use for substances with overdose liability remain low. In this regard, distinguishing between substances of low overdose risk and high overdose risk will be critical in prevention and education efforts in the future.

Societal patterns regarding life course bonds that may reduce substance use create several possibilities for more recent youth cohorts. For example, cohabitation is increasingly common (Mernitz 2018), and research is mixed regarding its effect on substance use (Siennick, et al 2014; Lonardo et al. 2010). Additionally, employment for recent cohorts of young people has gone through rapid expansion and contraction. Within the last decade, young people have experienced both historically high unemployment on the heels of the Great Recession and more recently from COVID-19 and low unemployment in between. Such volatility may shape future patterns of substance use in ways that cannot be extrapolated from past periods of more stable economic periods. It is possible, however, that such volatility may contribute to distress that facilitates more harmful patterns of substance use. At the same time, inequality has continued to grow, and inequality has been shown to exacerbate drug-related morbidity and mortality (Katikireddi et al., 2017; Turner & Lloyd, 2003) and weaken population health more generally (Wilkinson & Pickett, 2006; Pickett & Wilkinson, 2015). Thus, economic and social trends indicate mechanisms that may prove somewhat detrimental for future cohorts. On the whole, there are both reasons for optimism for current youth cohorts as well as causes for concern. It is possible that these may even have countervailing effects for current youth cohorts. The uncertainty regarding these effects only makes the need for future prevention, intervention, and policy (see Table 1) all the more critical to ensure that current young people see a reversal in the midlife overdose mortality trends of the past two decades.

For those currently in midlife who have already experienced high overdose mortality rates within their birth cohorts, we also must begin to consider the impact of current trends on future health and well-being and its future impact on population dynamics. The growth in overdose among midlife adults may set up future population health trends in the following ways. Experiences of heavy substance use and non-fatal overdose in midlife may facilitate an earlier disablement process for some as they age into later life. In this manner, adverse effects of heavy substance use and lingering aftereffects of an overdose may create a scenario whereby current midlife individuals are aging into increasing limitations in life functioning at an earlier stage (Verbrugge & Jette, 1994). This may increase future needs for healthcare and caregiving at earlier stages of the life course for current midlife adults.

Yet, at the same time, heightened early mortality may lead to a future reduction in mortality at the earliest stages of the late life years for the current midlife cohort. As there is a significant socioeconomic curve to overdose mortality, those most vulnerable to fatal overdose in midlife in the present may be the same individuals who would suffer from heightened risk of morbidity and early mortality as they age in the future. Sadly, given socioeconomic stratification in health, this group would be expected to live shorter and unhealthier lives in their senior years relative to their more economically advantaged cohort members were they to survive the overdose trend. As such, although for unfortunate reasons, adults in this midlife cohort who survive to their senior years may be an overall healthier population of aging adults as a result of midlife mortality in this cohort. Yet, the chronic effects of heavy substance use and non-fatal overdoses into later life and related comorbidities may still result in costly healthcare for some, as has been the case with tobacco smoking (U.S. Department of Health and Human Services 2014; Xu et al. 2014). Finally, these cases of early life mortality will further shift the population curve when this cohort of adults age into later life. The current cohort of midlife adults is already considerably smaller than the Baby Boomer generation ahead of them. Heightened midlife mortality among contemporary middle aged adults will further increase the need for gerontologists and other aging specialists to prepare for a shift in scope and future needs (and possibly fewer resource needs) of the aging midlife population, as we should anticipate fewer midlife adults aging into their senior years than is presently the case, a trend exacerbated by heightened midlife overdose mortality during the early 21^st century.

Conclusions

The current life course stratification in overdose mortality has presented the opportunity to reconsider future approaches to prevention, intervention, and policy. Midlife overdose mortality has emerged as a pressing problem that demands attention not merely for intervening on contemporary deaths but also for the sake of forestalling future problems. The conceptualizations above provide a roadmap for future research that may yield more precise implementation of public health efforts that address the needs of the current midlife cohort, while also providing benefits to future cohorts. Future research as well as future prevention and intervention efforts must focus on the effects of midlife overdose mortality as a long-term issue.