BackgroundDeterioration of hand motor function is a possible risk factor of cognitive impairment in older adults. Despite a growing body of research, a lack of clarity exists regarding the relationships. This review offers a synthesis of existing observational studies evaluating the associations of handgrip strength and hand dexterity with cognitive performance in community-dwelling older adults.MethodsPubMed, PsycINFO, and ScienceDirect were systematically searched (search dates: 1990–2016), and relevant articles were cross-checked for related and relevant publications.ResultsTwenty-two observational studies assessed the association of handgrip strength or hand dexterity with cognitive performance; none evaluated handgrip strength and hand dexterity together. Handgrip strength was associated with global cognition, mostly assessed using the Mini-Mental State Examination, cross-sectionally and longitudinally. Also, one cross-sectional and three longitudinal studies found an association with cognitive domains, such as language, memory, visuospatial ability, working memory, and processing speed. Hand dexterity was only assessed cross-sectionally in four studies. These studies found an association with cognitive domains, such as executive function.ConclusionsAlthough handgrip strength was associated with cognitive performance, it is unclear which variable at baseline affects the other in the long-term. Cross-sectional studies indicate an association between hand dexterity and cognitive performance, yet longitudinal studies are needed to elucidate this association. The interaction effects of both decreased grip strength and hand dexterity on cognitive performance is still unclear; therefore, future studies will need to consider the interaction of the three variables cross-sectionally and longitudinally.

The aims of this systematic review were to investigate what kind of cognitive leisure activities have been used in intervention studies targeting older adults, and whether these activities improve cognitive function or inhibit cognitive decline. Based on the PRISMA declaration, we searched keywords using three electronic databases: PubMed, PsycINFO and Psy-cARTICLES. Intervention studies involving cognitive leisure activities with cognitive assessments set as outcomes were included. We regarded cognitive leisure activities as activities for enjoyment or well-being that cause intellectual stimulation (e.g. reading, playing board games). To investigate the influence of each activity on cognitive domains, multicomponent programs (e.g. combined music and art) were excluded. In total, 20 studies were included in the evaluation. Consequently, intervention studies related to arts, writing, board games, reading, handicrafts, a crossword puzzle and learning computer skills were identified. Of the 20 studies, 13 showed improvement in some cognitive domain. In 12 of these 13 studies, the intervention effects were not observed in a specific cognitive domain; rather, the intervention effects were observed across multiple cognitive domains and on working memory. The results of the present review suggest that cognitive function in older adults can be improved through cognitive leisure activity interventions. Activities related to learning new skills, that cause strong intellectual stimulation and that include communication elements were considered particularly effective tools. However, as the number of studies is small, more high-quality research needs to be accumulated.

BackgroundAn association between handgrip strength, hand dexterity and global cognition is suggested; however, it is unclear whether both hand motor functions are associated with executive function, which is important for performing daily activities. Understanding this association will help identify motor risk factors for impairment of executive function in late adulthood. We aim to investigate the relationship of handgrip strength and hand dexterity with executive function in physically and mentally healthy community-dwelling older adults.MethodsThree hundred and twenty-six older adults (287 women, mean age ± SD, 70.1 ± 5.6) underwent handgrip strength and hand dexterity tests using a hand dynamometer and the Purdue Pegboard Test (PPT), respectively. Executive function was evaluated with the Trail Making Test (TMT)-A, TMT-B and Digit symbol; global cognition was assessed with the Mini-Mental State Examination (MMSE).ResultsAge-group differences showed that the younger groups (60–64, 65–69 and 70–74) had a significant better PPT and executive function performance than the oldest group (75 and older), whereas no significant age differences were observed for handgrip strength. Multiple regression analysis adjusted for potential covariates, including MMSE scores, showed that TMT-A, TMT-B, and Digit symbol were significantly associated with PPT scores; however, no significant association was observed between executive function variables and handgrip strength.ConclusionsHand dexterity is vulnerable to the effects of aging and, contrary to handgrip strength, it strongly associates with executive function, independent of global cognition. Our results suggest that assessing hand dexterity may help identify individuals at higher risk of impairment of executive function among high-functioning older adults.