Association between cognitive function and life-space mobility in older adults: results from the FRéLE longitudinal study

BACKGROUND: Cross-sectional and longitudinal studies show conflicting results regarding the association between cognition and life-space mobility, and little is known regarding the mediators and moderators of the association. The aim of this study was to investigate the association between cognition and life-space mobility in older adults, as well as the intervening variables modifying the relationship. METHODS: Community-dwelling older adults aged 65 years and older (N = 1643) were assessed at three time points over a period of 2 years. Growth mixture models with mediation and moderation analysis were utilised to investigate association between cognitive function and life-space mobility. The potential mediators and moderators were depressive symptoms, locus of control, gait speed and grip strength. Analysis was controlled for age, sex, education, annual income, number of chronic illnesses, and living site. RESULTS: The direct association between initial scores of cognitive function and life-space was mediated by initial scores of depressive symptoms and gait speed, and moderated by initial scores of grip strength. No direct association between change in cognitive function and change in life-space mobility was found; the scores were mediated by change in depressive symptoms. CONCLUSIONS: We conclude that the relationship between change in cognitive function and life-space mobility in older adults is not well-defined over an observation period of 2 years. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12877-018-0908-y) contains supplementary material, which is available to authorized users.