Metabolic Syndrome and Mobility Dysfunction in Older Adults With and Without Histories of Traumatic Brain Injury: The Mediating Role of Cognition

Objective: Older adults are more susceptible than the general population to developing metabolic syndrome (i.e., three or more cardiovascular risk factors [MetS]), physical limitations, and traumatic brain injury (TBI). Recent research has demonstrated that cognition may moderate the negative association between MetS and mobility dysfunction in older adults. This study sought to determine if cognition mediates the relationship between MetS and mobility dysfunction and if this relationship differs in older adults with a history of TBI. Method: Participants (N = 20,156) were from the National Alzheimer's Coordinating Center's Uniform Data Set. Mediation models were tested to assess if processing speed, executive functioning, immediate memory, and delayed memory would independently mediate the association between MetS and mobility dysfunction. Results: Investigation of mediation models revealed that MetS had a significant indirect effect on mobility dysfunction through processing speed (b = .0674, 95% CI [.0412, .0953]) and executive functioning (b = .0354, 95% CI [.0228, .0493]). When TBI was included in the model as a moderator, MetS was not found to moderate the mediating effects of any of the cognitive variables. There were no significant indirect effects for immediate or delayed memory in either model. Conclusions: Findings elucidate potential pathways by which MetS contributes to mobility dysfunction in older adults through specific reductions in processing speed and executive functioning capabilities.