Specifying the Link Between Brain Integrity, Cognitive, and Affective Functioning in Aging Individuals

ThIS special issue presents methodologically innovative w ork that advances our understanding of the relationship between cognitive performance and affect, in particular highlighting the contribution of brain to behavior. Studies investigating the effects of aging on brain anatomy and physiology suggest targeted areas which are most affected by aging, and are characterized by cerebral atrophy, synaptic loss, changes in receptor numbers and function, among other anatomical changes. These changes are likely responsible for most of the observed age-related changes in cognitive function reported in many studies of aging. Identifying precisely how these brain changes affect cognition is a formidable challenge, though new testing methodologies, along with advances in neuroimaging analysis techniques, have led to testable hypotheses and models of the link between brain and behavior. A key question in the field of cognitive aging is whether we can identify factors that can account for the considerable variability that exists in cognitive decline across normal aging individuals. For example, research shows that extensive brain atrophy and synaptic density reduction can result in dementia symptoms in some individuals, while surprisingly, others are much more resilient and asymptomatic, despite having equivalent neural degradation (Katzman et al., 1988). Such protection from dementia symptoms has been linked to elevated “cognitive reserve,” defined as one’s efficiency at using existing neural circuits, and/or one’s flexibility in using compensatory mechanisms to accomplish cognitive tasks. Propensity for physical activity, among other factors (Stern, 2012), appears to elevate cognitive reserve. It is possible that such a stimulating environment fosters plasticity, and neurogenesis, through the production of growth factors within the brain ( h otting & Roder, 2013), and these in turn