Cognitive Correlates of Timed Up and Go Subtasks in Older People With Preserved Cognition, Mild Cognitive Impairment, and Alzheimer's Disease.

OBJECTIVE: To determine whether impaired Timed Up and Go Test (TUG) subtask performances are associated with specific cognitive domains among older people with preserved cognition (PC), mild cognitive impairment (MCI), and mild Alzheimer's disease (AD).
DESIGN: TUG subtasks performances were assessed by the Qualisys motion system. Cognition was assessed by Addenbrooke's Cognitive Examination and the Frontal Assessment Battery (FAB).
RESULTS: The highest correlations with transition subtasks were with aspects of executive function, i.e. the fluency domain in the PC group (n = 40), FAB scores in the MCI group (n = 40), and the visuospatial domain in the AD group (n = 38). No significant associations were found between the walking subtasks and cognition in any group. Multivariate linear regression models identified the fluency domain as an independent predictor of turn-to-walk and turn-to-sit measures in the PC group, and the visuospatial domain as an independent predictor of turn-to-walk and turn-to-sit measures in the AD group, adjusted for age and sex.
CONCLUSIONS: Poorer executive functioning was associated with impaired transition mobility in all groups. The significant associations between visuospatial impairment and poor transition mobility in the AD participants may provide insight into why this group has an elevated fall risk.