Relationship between cognitive domains, physical performance, and gait in elderly and demented subjects.

Cognitive function declines with age, with studies linking decreases in cognitive function to increased fall risk. The association between declines in specific cognitive domains and the development of gait and physical performance deficits has not been established. The current cross-sectional study was designed to address these issues using well characterized control subjects (n = 50), and individuals with early stage dementia (n = 50) tightly matched for age, gender, and education. All participants received detailed cognitive assessments for global cognitive function, as well as for processing speed, verbal fluency, and executive function. Additionally, participants were administered single- and dual-task gait assessments (GAITRite) and Short Physical Performance Battery (SPPB) measures of physical performance (gait, balance, chair stands). Data show that all measures of cognitive function correlated significantly with measures of gait and physical performance when analyzed in all subjects or just subjects with dementia. However, data also reveal that measures of processing speed and verbal fluency correlated significantly with multiple aspects of motor performance in non-demented, control subjects, even when corrected for age. There was no correlation between global cognitive function and motor performance, and only limited relationship between executive function and motor performance in non-demented, control subjects. These studies reveal the complex interactions between cognitive function and gait/physical performance in the context of aging and dementia, and suggest that impairments in specific cognitive domains might undermine gait and physical performance and thus exacerbate fall risk in the elderly.