Busyness, mental engagement, and stress: Relationships to neurocognitive aging and behavior

Impact of individual differences in cognitive reserve, stress, and busyness on episodic memory: an fMRI analysis of the Alabama Brain Study On Risk for Dementia

Cognitive reserve (CR) and busyness can boost memory, whereas stress can impair memory. Nevertheless, extant research has not yet examined busyness in conjunction with CR and stress, nor whether CR or stress moderate the relationship between busyness and episodic memory. Middle-aged and older adult participants (N = 71; ages 50-74; 31% African-American) answered lifestyle questionnaires and completed a visual paired-associate memory fMRI task. Dimension reduction techniques identified two latent CR factors-personal CR (own education; occupation complexity; socioeconomic status) and parental education (mother's/father's education), and identified two latent stress factors-external stress (neighborhood stress/violence; financial strain) and personal stress (perceived stress; work/personal stress). We cast these latent factors into a series of regression models, revealing that (1) in isolation, higher busyness predicted better episodic memory, (2) higher external stress predicted worse memory, (3) both greater personal CR and greater parental education predicted better memory, (4) busyness did not interact with stress nor with CR, and (5) in a combined model, higher parental education and lower external stress were significant independent predictors. Neuroimaging data revealed that higher CR was associated with more efficient brain activity in the hippocampus and posterior cingulate during successful episodic memory retrieval, whereas higher personal stress was associated with heightened activity in the precuneus. No interactions or main effects of busyness were observed for the fMRI data. Thus, although busyness was associated with superior episodic memory, busyness did not modulate brain activity during episodic memory retrieval, nor did CR or stress moderate the relationship between busyness and associative memory.

Hemispheric organization of the brain and its prevailing impact on the neuropsychology of aging

Age differences in brain hemispheric asymmetry have figured prominently in the neuropsychology of aging. Here, a broad overview of these empirical and theoretical approaches is provided that dates back to the 1970s and continues to the present day. Methodological advances often brought new evidence to bear on older ideas and promoted the development of new ones. The deficit-focused hypothesis of accelerated right-hemisphere aging is reviewed first, followed by subsequent accounts pertaining to compensation, reserve, and their potential hemispheric underpinnings. Structural and functional neuroimaging reveal important and consistent age-related patterns, including indications of reduced brain asymmetry in older relative to younger adults. While not mutually exclusive, different neuropsychologic theories of aging offer divergent interpretations of such patterns, including age-related reductions in neural specificity (dedifferentiation) and age-related compensatory bilateral recruitment [e.g., Hemispheric Asymmetry Reduction in Older Adults (HAROLD); Compensation-Related Utilization of Neural Circuits Hypothesis (CRUNCH)]. Further, recent neurobehavioral evidence suggests that the right hemisphere plays a unique role in resisting the neurocognitive effects of aging via brain reserve. Future advances in human cognitive neuroscience, including neurostimulation methods for targeted interventions, along with analytic techniques informed by machine learning promise new insights into the neuropsychology of aging and the role of hemispheric processes in resilience and decline.