The Benefits of a Sense of Purpose in Life for Healthier Cognitive Aging: Commentary on Sense of Purpose as a Potential Buffer between Mental Health and Subjective Cognitive Decline

The recent findings reported by Pfund and colleagues (2022) point to the importance of a sense of purpose in life for healthier cognitive aging outcomes. Specifically, Pfund and colleagues report that in a diverse sample of 595 older adults, a greater sense of purpose is associated with fewer self-reported cognitive complaints as measured by the AD8, a frequently used screening tool for dementia. Such subjective perceptions of cognition are important because not only are they burdensome for individuals, but they predict risk of future objective cognitive impairments. These findings show the relevance of purpose for this cognitive outcome, which fits more broadly with the burgeoning literature on sense of purpose and healthier cognitive aging outcomes across the lifespan.

A sense of purpose in life is the feeling that one’s life is goal-oriented and has direction (McKnight and Kashdan, 2009). Purpose is emerging as a robust protective factor that promotes better cognitive outcomes across the spectrum of dementia risk, from the preclinical phase to the end of life (Sutin et al., 2021d). Prior to cognitive impairment, for example, purpose is associated with better verbal fluency and episodic memory function (Sutin et al., 2022b) and less age-related cognitive decline (Kim et al., 2019b). Individuals with more purpose are also less likely to have motoric cognitive risk syndrome (MCR), a pre-dementia syndrome that predicts developing dementia, and over time they are less likely to develop incident MCR (Sutin et al., 2021b). Higher purpose in life has likewise been associated with lower risk of mild cognitive impairment (MCI; Wilson et al., 2021, Boyle et al., 2010). Purpose in life is further associated with healthier behavioral and clinical profiles (Kim et al., 2019a) that are protective against dementia. It is not surprising, then, that individuals with a higher sense of purpose have a lower risk of incident dementia: In a meta-analysis of six prospective studies (N = 53,499; n = 5,862 incident dementia), it was found that among participants with healthy cognition at baseline, those with a higher sense of purpose had an approximately 30% lower risk of developing incident dementia over an up to 17-year follow-up period (HR = 0.77, 95% CI = 0.73–0.81, p < 0.001), a protective association that replicated in each of the six samples (Sutin et al., 2021a). Feeling purposeful continues to be protective even after dementia onset: A greater sense of purpose measured prior to dementia is associated with fewer behavioral and psychological symptoms of dementia (BPSD, also known as neuropsychiatric symptoms) in the last year of life, as reported by a knowledgeable proxy (Sutin et al., 2022).

The present work by Pfund and colleagues builds and expands on this literature by addressing purpose as a buffer against the harmful effects of loneliness and depressive symptoms on cognitive complaints, and whether these associations are moderated by race. They found that higher purpose ameliorates the association between loneliness (but not depression) on cognitive complaints and that this interaction is further moderated by race. Pfund and colleagues’ findings are intriguing and add to the literature on purpose and cognitive aging in at least three ways:

First, the findings suggest that purpose in life may be a psychological resource that reduces the harmful effects of other risk factors (e.g., loneliness) on cognitive outcomes (e.g., cognitive complaints). Most research on purpose and cognitive health has focused on the main effect of purpose on a cognitive outcome, but purpose may also alleviate the risk of other harmful factors. Purpose, for example, may be protective against poor cognitive outcomes because it promotes brain and cognitive reserve (Stern et al., 2020). Across the lifespan, higher purpose may build neural and psychological resources to resist or delay neurodegeneration, even among individuals with some risk factors, such as loneliness. In addition, purpose may act as a resilience factor to help withstand neural losses and preserve cognition in the presence of neuropathology (Boyle et al., 2012). To the extent that purpose can be cultivated (see below), it is a promising target to help reduce the impact of other risk factors on cognitive outcomes and bolster the brain’s defenses against the risk of neurodegeneration and/or to better cope with neuropathology.

Second, the three-way interaction suggested that the buffering effect of purpose on loneliness was stronger for Black/African American participants than for white participants. Given that Black/African American adults are at greater risk of poor cognitive outcomes compared to white adults (Power et al., 2021), identifying factors that can be leveraged to reduce risk for populations that bear a disproportionate burden of dementia is highly significant. Interactions, especially three-way interactions, however, should be interpreted with caution until replicated because interactions are difficult to replicate (Sherman and Pashler, 2019). Indeed, even within this study, the other tested two- and three-way interactions did not replicate. Furthermore, other studies that test race as a moderator often find no interaction between purpose and race (or other socio-demographic factors; Sutin et al., 2021c, Sutin et al., 2021b, Wilson et al., 2021, Boyle et al., 2010). Purpose may have more protective effects among sociodemographic groups at higher risk for poor cognitive outcomes. Still, a similar association across populations is also an important finding. It suggests that the beneficial protective effects of purpose are not limited to those with the most resources or lowest risk profiles. Individuals across the spectrum, including those at greatest risk, benefit from feeling more purposeful.

Third, the results also point to the importance of loneliness for cognitive outcomes. That is, even the benefits of higher purpose could not completely eliminate the harmful association between loneliness and cognitive complaints. Similar to purpose, loneliness has emerged recently as a significant predictor of cognitive outcomes (in the opposite direction of purpose; Luchetti et al., 2020). There is a basic human need to be accepted and to connect with others; loneliness can occur when this need is not met. There are cognitive consequences to this feeling: Loneliness increases risk of dementia and other cognitive impairments, perhaps in part but not entirely through greater at-risk behavioral and clinical profiles (Luchetti et al., 2020). Loneliness itself may also act as a mechanism between purpose and cognition: Higher purpose is protective against the development of new feelings of loneliness (Sutin et al., 2022a), and, to the extent that feeling connected protects cognitive health, it may lower the risk of developing a cognitive impairment.

The findings from Pfund and colleagues (2022) build nicely on research recently published in International Psychogeriatrics. A review of the literature on loneliness and depression in a recent issue of International Psychogeriatrics, for example, evaluated the evidence for loneliness as a prospective predictor of depressive symptoms and clinical depression in longitudinal studies. Specifically, Van As and colleagues (2022) reviewed the published literature on loneliness and depression and found that among older adults, higher loneliness is associated with increases in depressive symptoms over time and with lower likelihood of remittance over follow-up. This work points to the harmful effect of loneliness on mental health, as well as cognitive health. Future research could address whether purpose in life buffers the association between loneliness and depressive symptoms, as was the case with cognitive symptoms. The findings of Pfund and colleagues (2022) are also consistent with recent research from our group published in International Psychogeriatrics (Sutin et al., 2022b) on the role of purpose in healthier cognition. Specifically, we examined the relation between purpose and both verbal fluency and episodic memory measured with standard cognitive tasks. We found that a greater sense of purpose was associated with better verbal fluency and episodic memory in 27 and 35 of the 29 and 37 samples tested, respectively, and that the meta-analytic association was significant for the overall association for both cognitive functions. This consistency suggests a robust association between purpose and objective cognitive performance. The results from Pfund and colleagues (2022) suggest that this association also extends to subjective cognition measured with the AD8.

More generally, the findings for purpose are consistent with the observational literature that points to the potential utility of purpose in life as a target of intervention for healthier cognitive aging. This evidence can be put in the context of work on purpose in life in other domains that demonstrate its malleability. Experimental work, for example, finds that purpose in life can be increased temporarily (Scott and Cohen, 2020). Several interventions have also demonstrated that purpose in life can be increased and sustained through intervention, even when the intervention is not targeted specifically at purpose (Park et al., 2019). Much of the intervention work has been conducted within the cancer domain. The benefits of such established interventions may also be apparent in populations at risk for poor cognitive outcomes. Future research could evaluate whether increases in purpose through intervention support better cognitive function over time.

In parallel with intervention work, future research could also better identify the mechanisms through which purpose is associated with cognitive outcomes. Behavioral (e.g., greater physical activity) and clinical (e.g., fewer chronic diseases) factors account for only a small part of the association between purpose and risk of cognitive impairment (Sutin et al., 2021a). Aspects of social health, such as loneliness, are also promising mechanisms to test. There are likely to be other behavioral factors (e.g., sleep), cognitive activities (e.g., reading, work complexity), and aspects of relationships (e.g., relationship quality) associated with purpose that may promote healthier cognition. Such mechanisms of purpose may help to protect the brain by building stronger neural connections and synapses that allow individuals higher in purpose to cope better with neuropathology and delay declines in cognitive function. Future work should also examine the more direct neurobiological underpinnings of these associations. For example, it could be informative to test whether purpose in life is related to in-vivo neuropathological markers of Alzheimer’s disease, such as beta-amyloid and phosphorylated tau accumulation. A mechanism-focused approach using both longitudinal and experimental designs and that also incorporates relevant biomarkers would help to better evaluate the pathways through which purpose supports cognition and the potential points of intervention to leverage purpose for better cognitive health across the lifespan.