Executive function and life-space mobility in old age.

Background: Life-space assessment incorporates all movements in terms of the distance from home, the frequency of movement and the need of assistance for movement. Executive function (EF) is an important higher order cognitive ability that controls and guides people's goal-directed actions. We examined the cross-sectional and longitudinal associations between EF and life-space mobility, and investigated if perceived walking difficulties, lower extremity performance, and transportation difficulties explain the association.
Methods: 157 community-dwelling persons aged 76-91 years participated in the study at the baseline, and 103 of them in 2-year follow-up study. Based on the distribution on the Trail Making Test participants were categorized into tertiles of EF. Life-space mobility was assessed using the Life-Space Assessment (range 0-120). Perceived walking difficulties and transportation difficulties were self-reported, and lower extremity performance was assessed with the short physical performance battery (SPPB). Adjustments were made for gender, age, number of chronic conditions, and years of education.
Results: Average age of participants at the baseline was 82.6 (SD 4.2) years and 61% were women. Individuals with poor EF had lower life-space mobility compared to those with good EF. SPPB and transportation difficulties explained the association. Over the 2-year follow-up, those with poor EF at the baseline showed steeper decline but the difference did not quite reach statistical significance (p = 0.068).
Conclusions: People with better executive function had higher life-space mobility. This was explained by better lower extremity performance and absence of transportation difficulties. Cognitive decline may hinder access to community amenities, which in turn may further accelerate cognitive decline.