Physical Function Differences Between the Stages From Normal Cognition to Moderate Alzheimer Disease

Abstract

Objectives: We investigated the differences in the physical function test results across stages from normal cognition (NC) to moderate Alzheimer disease (AD) and how risk factors of physical function decline are correlated with the physical function test results.

Design: A cross-sectional study of outpatients at the Memory Disorder Outpatient Center of Japan's National Center of Geriatrics and Gerontology.

Participants: We enrolled 882 individuals aged ≥65 diagnosed with NC (n = 210), amnestic mild cognitive impairment (aMCI; n = 273), mild AD (n = 181) or moderate AD (n = 197).

Measurements: We measured the participants' results for functional reach (FR), the one-leg standing (OLS) test, the Timed Up and Go (TUG) test, tandem gait (TG), and grip strength (GS). A one-way analysis of covariance (ANCOVA) was used to identify significant differences among the groups' results on the physical function tests, controlling for age, sex, educational year, Mini-Nutritional Assessment, senior activity and exercise frequency, low-density lipoprotein, body mass index, free-fat mass index, and assistance for the TUG test. Multiple regression analysis was also used to investigate the correlation between these covariates and physical function tests results.

Results: The ANCOVA showed that FR, OLS, and TG were significantly worse among the individuals with aMCI, mild AD, or moderate AD compared with NC. However, TUG was significantly worse only in the moderate AD group compared with the NC, aMCI, and mild AD group. Multiple regression analysis showed that aging was correlated with poorer scores on all physical function tests, women had poorer scores on FR and GS than men, and low frequency of senior activity was significantly correlated with poorer scores on FR, OLS, and TG.

Conclusion: Postural impairment and instability on TG was seen in earlier AD stages compared with instability on TUG. As were the covariates of age and sex, senior activity frequency was significantly related to 2 or more physical function tests.

Keywords: ANCOVA; Alzheimer disease; amnestic MCI; gait; postural function.