A Review of Functional Brain Imaging Correlates of Successful Cognitive Aging

Preserved cognitive performance is a key feature of successful aging. Several theoretical models (compensation, hemispheric asymmetry reduction, and posterior-anterior shift) have been proposed to explain the putative underlying relationship between brain function and performance. We aimed to review imaging studies of the association between brain functional response and cognitive performance among healthy younger and older adults in order to understand the neural correlates of successful cognitive aging. MEDLINE-indexed articles published between January 1989 and May 2008, and bibliographies of these articles and related reviews were searched. Studies that measured brain function using fMRI or PET, evaluated cognitive performance, analyzed how cognitive performance related to brain response, and studied healthy older individuals were included. Forty-seven of 276 articles met these criteria. Eighty-one percent of the studies reported some brain regions in which greater activation related to better cognitive performance among older participants. This association was not universal, however, and was seen mainly in frontal cortex brain response and seemed to be more common among older compared to younger individuals. This review supports the notion of compensatory increases in brain activity in old age resulting in better cognitive performance, as suggested by hemispheric asymmetry reduction and posterior-anterior shift models of functional brain aging. However, a simple model of bigger structure → greater brain response → better cognitive performance may not be accurate. Suggestions for future research are discussed.