Sense of Purpose in Life and Healthier Cognitive Aging

Abstract

Individuals with a greater sense of purpose maintain better cognitive function and have lower dementia risk. We review evidence linking purpose in life to healthier cognitive aging across adulthood and diverse demographic groups. Experimental work is now needed to test causal mechanisms to evaluate the utility of purpose as an intervention target.

Alzheimer’s disease and related dementias (ADRD) are among the most pressing public health challenges facing society. The prevalence of ADRD is high across the globe and a particular challenge in lower-income countries [1]. Given that treatment options are limited, prevention is seen as the best strategy for managing ADRD [1]. Novel targets of intervention are urgently needed to meet this challenge. One underrecognized but intriguing intervention target is purpose in life. Observational evidence suggests that sense of purpose may be a powerful protective factor that supports healthier cognitive aging [2] and protects against modifiable risk factors for ADRD (e.g., physical inactivity, problems sleeping, elevated body weight [3]). Cultivating a greater sense of purpose in life may have cascading beneficial effects across the lifespan that culminate in protection against dementia.

Purpose in Life

Purpose comes in many forms, and the reasons for a sense of purpose are many, varied, sometimes overlapping, and can even be contradictory – what is purposeful to one person may be trivial to another or two people may engage in the same behavior, but only one finds it purposeful [4]. Despite the individuality in what is deemed purposeful, a sense of purpose is knowable and can be measured reliably. What is common is that purpose brings feelings that one’s life is goal-oriented, driven, and has direction [4]. These feelings are associated with consequential health outcomes: Individuals with a greater sense of purpose live longer and with fewer diseases [5]. Recent advances demonstrate that the benefits of a purposeful life extend to healthier cognitive aging.

It is important to note that purpose in life is one core component of a meaningful life, which is a broad construct that encompasses several narrower components, including purpose. Althoug meaning in life and purpose in life are theoretically distinguishable [4], the cognitive correlates are similar [6]. We focus on the empirical evidence for purpose in life and healthier cognitive aging. Note, however, that the cognitive correlates and processes associated with meaning in life may be both similar and distinct from those for purpose in life.

Purpose in life and the spectrum of dementia

The trajectory of dementia ranges from preclinical (no impairment/symptoms) to late stage (severe impairment). To bring coherence to this literature and illustrate the pervasive link between sense of purpose and healthier cognitive aging, we highlight recent findings across this spectrum, from preclinical cognitive markers to behavioral symptoms of dementia in the last year of life (Figure 1).

Figure 1. Relevance of sense of purpose in life to cognitive aging across adulthood.

An overview of the relation between a sense of purpose in life and its association with factors across the spectrum of dementia, including behavioral and clinical risk factors across adulthood earlier in adulthood, markers of cognitive health prior to dementia, markers of cognition across the transition to dementia, and its association with better outcomes after diagnosis.

Prior to impairment, middle-aged and older adults with a higher sense of purpose in life perform better on tasks that measure episodic memory and verbal fluency [6]. That is, they are able to remember more words (episodic memory) and quickly list examples of a category (e.g., animals; verbal fluency). The ability to remember and the ability to organize information are key markers of cognitive health that are necessary for behaviors to maintain independence in older adulthood. In addition to objective performance, how individuals perceive their cognition is another important predictor of future cognitive decline. Specifically, some individuals notice their cognitive abilities declining before deficits are detected on standard cognitive tests. Similar to objective performance, individuals with a higher sense of purpose perceive their memory function to be better than individuals with a lower sense of purpose and maintain these perceptions over 10 years [7]. Poor self-rated memory takes on even greater importance when combined with slow walking speed. Such a combination, in the absence of objective impairment, is termed motoric cognitive risk syndrome (MCR) and is a significant risk factor for incident dementia. Again, purpose has a powerful protective association: Individuals with a higher sense of purpose are less likely to have MCR when measured concurrently and are less likely to develop MCR over a decade [8].

Given the relationship between sense of purpose and healthier cognitive aging, it is no surprise that this pattern of association culminates in lower risk of developing Alzheimer’s disease [9] and dementia [10]. Indeed, a recent meta-analysis of six prospective studies found a higher sense of purpose is associated consistently with lower risk of developing dementia, even after accounting for sociodemographic, clinical, and behavioral risk factors [10]. Even individuals with the lowest risk profiles earlier in life may still develop ADRD. Of note, then, is that purpose continues to be associated with better outcomes after the onset of impairment. Behavioral and psychological symptoms of dementia (BPSD) are among the most difficult aspects of dementia for caregivers to manage (e.g., uncontrolled temper, confusion). Individuals with a higher sense of purpose, as self-reported before the onset of cognitive impairment, have fewer BPSD in their last year of life, as reported by a knowledgeable proxy [11]. Further, individuals with dementia who report that they feel purposeful are more committed to their goal strivings, and such engagement increases feelings of momentary purpose [12].

This greater engagement, which is at the core of a sense of purpose, may be one key driver of cognitive outcomes. The pathway to better cognitive outcomes is often through healthier clinical and behavioral profiles (e.g., fewer chronic diseases, greater physical activity). And while purpose is associated with such profiles, clinical and behavioral factors only account for a small part of the relation with dementia risk [9, 10]. Engagement in daily life, in the form of greater emotional resilience, persistence, attention, effort, and social integration, keep purposeful individuals motivated and striving for their goals [4], which may also protect the brain. Mechanistically, these different forms of engagement may help build both the brain reserve (e.g., stronger neuronal connections and synapses) and the cognitive reserve (e.g., the ability of the brain to cope with changes caused by age and pathology) that helps maintain cognitive function in older adulthood [13].

For whom is purpose protective?

The vast majority of research on purpose in life and cognition has used samples from the United States and Europe. Much more research is needed to evaluate whether purpose has similar protective associations in non-Western countries, including cultures that are more collectivistic, practice different religions, have different political structures, etc. The emerging evidence from within Western cultures, however, indicates that purpose is widely protective. That is, most studies that test for moderators find that the beneficial cognitive outcomes associated with purpose are similar across age, sex/gender, race/ethnicity, and educational and income strata [9, 10].

Interestingly, there is suggestive evidence that sense of purpose may be more protective in environments with relatively fewer economic resources. A meta-analysis of purpose and episodic memory in 32 countries, for example, found that the positive association was apparent and statistically significant in 30 countries, and the association was slightly stronger in relatively lower-income countries, as measured by gross domestic product [6]. That is, individuals with a higher sense of purpose performed better on a cognitive task (remembered more words) in economic environments in which it can be challenging to maintain cognitive health. This preliminary work is promising because it suggests that purpose is generally protective across demographic groups and even more protective in vulnerable populations and thus not limited to populations with the most resources.

The potential of purpose as a target of intervention

The observational evidence suggests that sense of purpose in life is a promising target of intervention for better cognitive outcomes. This evidence fits with Stage 0 of the NIH Stage Model for Behavioral Intervention Development that begins with basic science knowledge on a promising target. The next step is the creation or adaptation of behavioral interventions for sense of purpose and the basic experimental work to test such interventions. Experimental research in other domains indicates that purpose can be increased momentarily and that such manipulations have an effect compared to control conditions [14]. These experiments could be modified and expanded to cognitive outcomes to establish proof of concept (e.g., whether participants perform better on cognitive tasks after induced to feel more purposeful).

Preliminary evidence suggests that sense of purpose (and meaning) increases through intervention among patients with cancer [15]. Additional work could evaluate (a) the most effective way to increase purpose (e.g., life story interventions, mindfulness interventions, etc.), (b) whether this effect extends to other popluations, particularly those at high risk for cognive impairment, and (c) similariites/differences across increases in purpose in life versus meaning in life (i.e., intervention studies typically include both meaning and purpose in the outcome measurement, and the two could be differentiated better). Such interventions could then be tested to evaluate whether increases in purpose sustain healthier cognitive function over time.

There remains a pressing need for behavioral interventions to support healthy cognitive aging and reduce risk of ADRD. We hope that bringing together the promising observational evidence for sense of purpose in life galvanizes high-quality research to evaluate experimentally whether purpose in life has a causal effect on cognition. Such evidence could then be leveraged into an evidence-based intervention for healthier cognitive outcomes in older adulthood, especially given this need for new behavioral interventions to reduce cognitive decline and risk of dementia.