Every day, we depend on our working memory, spatial cognition, and processing speed abilities to optimize productivity, interpersonal interactions, and psychological wellbeing. These cognitive functioning indices relate closely with academic and work performance, managing emotions, physical fitness, and a sense of fulfillment in personal and work relationships. They are linked intimately to complex cognitive skills (van Dijk et al., 2020). It is thus imperative to identify modifiable predictors of cognitive functioning in the brain to protect against aging-related cognitive decline and maximize the quality of life.
A decline in life satisfaction can worsen cognitive functioning over long periods via lifestyle factors (e.g., suboptimal diet and nutrition, lack of exercise) (Ratigan et al., 2016). Inadequate engagement in these health-enhancing pursuits could build up inflammation in EF-linked brain areas, thus negatively impacting cognitive functioning in adulthood (Grant et al., 2009). Possible pathways include long-term wear and tear of the hypothalamic-pituitary axis and brain regions linked to executive functioning (Zainal and Newman, 2022a). These processes may deteriorate working memory, spatial cognition, and processing speed across time.
Dr. Nur Hani Zainal
Similarly, it is plausible that a reduction in cognitive functioning may lead to a long-term decrease in life satisfaction. Working memory, processing speed, spatial cognition, and related capacities are essential to meaningful activities and feelings of gratification in personal and professional relationships and other spheres of health throughout life (Baumeister et al., 2007). These cognitive functioning markers safeguard against reduced life satisfaction by facilitating effective problem-solving, and choices (Swanson and Fung, 2016). For example, stronger working memory, processing speed, and related domains coincided with better tolerance for stress and trading off immediate rewards for long-term values and life goals (Hofmann et al., 2012). Therefore, reduction in cognitive functioning abilities could precede a future decline in life satisfaction.
Nonetheless, the literature on this topic has several limitations. Most of the studies have been cross-sectional (i.e., across a single time-point) and thus do not permit inferences between cause and effect (e.g., Toh et al., 2020). Also, most studies used statistical methods that did not differentiate between between-person (trait-like individual differences) and within-person (state-like) relations. Distinguishing within- and between-person relations is necessary because they may vary in magnitude and direction. The preceding theories emphasize change-to-future change relations within persons rather than between persons (Wright and Woods, 2020).
Clinical implications
Our recent work (Zainal and Newman, 2022b) added to the literature by using an advanced statistical method to determine the relations between change in life satisfaction and future change in cognitive functioning domains within persons. The choice of an advanced statistical technique minimizes biases due to the passage of time and assessment unreliability. It also adjusts for between-person effects (Klopack and Wickrama, 2020). Improving understanding of the within-person factors leading to the deterioration of cognitive functioning and life satisfaction is crucial given the rising rates of psychiatric and neurocognitive illnesses (Cui et al., 2020). Identifying these changeable risk factors can optimize prevention, early detection, and treatment approaches.
Dr. Michelle G. Newman
Specifically, we analyzed the publicly available Swedish Adoption/Twin Study of Aging (SATSA) dataset (Petkus et al., 2017). Their dataset comprised 520 middle- to older-aged twin adults without dementia. Participants provided data across 23 years with five time points. Each time lag ranged from 3 to 11 years. The analyses demonstrated that greater decreases in life satisfaction predicted larger future declines in processing speed, verbal working memory, and spatial cognition. Moreover, declines in verbal working memory and processing speed predicted a reduction in life satisfaction. However, change in spatial awareness did not predict change in life satisfaction.
Our study offers multiple theoretical perspectives. Scar theories propose that decreased life satisfaction and related mental health problems can compromise working memory, processing speed, and spatial cognition in the long term. This scarring process occurs through the buildup of allostatic load, such as increased biomarkers of chronic stress (e.g., cortisol) and inflammation (e.g., interleukin-6, C-reactive protein) (Fancourt and Steptoe, 2020; Zainal and Newman, 2021a). Also, findings suggest the importance of executive functioning domains to attain desired milestones and aspirations to enhance a sense of fulfillment (Baddeley, 2013; Toh and Yang, 2020). Reductions in these cognitive functioning capacities could, over time, adversely affect the ability to engage in daily living activities and manage negative moods.
Limitations of our study include the lack of a multiple-assessment approach to measuring diverse cognitive functioning domains. Also, the absence of cognitive self-reports is a shortcoming since perceived cognitive difficulties might not align with performance on cognitive tests. Relatedly, future studies should administer cognitive tests that parallel and transfer to everyday tasks. However, our study’s strengths include the robust findings across different intervals between study waves, advanced statistics, and the large sample size.
If future studies replicate a similar pattern of results, the clinical applications of this study merit attention. Mindfulness-based interventions can promote working memory, sustained awareness, and spatial cognition or protect against cognitive decline (Jha et al., 2019; Zainal and Newman, 2021b). Further, clinical science can profit from exploring cognitive-behavioral therapies to improve adults’ cognitive function or life satisfaction (Sok et al., 2021).
Dr. Zainal recently accepted a 2-year postdoctoral research associate position at Harvard Medical School, Boston, starting in summer 2022. She received her Ph.D. from Pennsylvania State University, University Park, and completed a predoctoral clinical fellowship at the HMS-affiliated Massachusetts General Hospital – Cognitive Behavioral Scientist Track. Her research interests focus on how executive functioning, social cognition, and cognitive-behavioral strategies link to the etiology, maintenance, and treatment of anxiety and depressive disorders. Dr. Newman is a professor of psychology and psychiatry, and the director of the Center for the Treatment of Anxiety and Depression, at Pennsylvania State University. She has conducted basic and applied research on anxiety disorders and depression and has published over 200 papers on these topics.
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