Cognitive and Neural Mechanisms of Learning and Interventions for Improvement Across the Adult Lifespan: A Systematic Review

There continues to be growing interest in the Science of Learning including identifying ways to apply findings. Presently, little is known about learning during healthy adulthood and methods to improve that learning. The main objective of the present systematic review is to identify and synthesize all recent cognitive and brain research investigating learning during healthy aging in adulthood. Searches were performed across Scopus, Web of Science, and ProQuest databases to identify published and unpublished studies conducted in healthy adults. Eligible studies reported measures of learning-related cognition, brain structure or function and their relationship with age, or effects of interventions to improve learning. Risk of bias was assessed using either the Mixed Methods Appraisal Tool or Critical Appraisal Skills Programme checklist. Search and screening were performed by three trained reviewers. Included studies were summarized using narrative synthesis and, for intervention studies, an effect direction plot. A total of 265 relevant studies were identified for inclusion. Studies were primarily lab-based cross-sectional studies conducted in Western contexts. Findings revealed an overall decline in learning-related cognitive and brain outcomes during healthy aging. However, declines were more pronounced in fluid abilities and explicit learning and memory while crystalized abilities and implicit learning and memory showed stability. Generally, higher education and socioeconomic status positively modulated age-related learning trajectories while baseline cognitive function influenced the effectiveness of interventions. Findings from the present systematic review are potentially limited by the exclusive focus on healthy aging and the small number of included studies conducted in non-Western contexts. Implications for policy, practice, and future research are discussed.