The apolipoprotein E e4 polymorphism is strongly associated with poor mobility performance test results but not self-reported limitation in older people.

Abstract

BACKGROUND: The apolipoprotein E (ApoE) e4 polymorphism is linked to increased mortality rates, Alzheimer's disease, and cardiovascular disease in older people, but previous studies have largely failed to detect an effect on self-reported mobility disability. We hypothesized that poor performance on mobility-related tests may provide a better measure of effects, and we aimed to estimate the extent to which the ApoE e4 allele increases risks of poor performance on measured mobility and self-reported mobility disability compared to e3/3, in a medium-sized population cohort. METHODS: Data were from 1262 people at baseline older than 65 years from the Longitudinal Aging Study Amsterdam (LASA), followed up for 6 years. Age- and sex-adjusted logistic regression models were used to explore associations. RESULTS: At baseline, those individuals with an e4 allele had an odds ratio of 2.26 (95% confidence interval, 1.31-3.90) for poor performance on gait speed testing (<0.4 m/s) and 1.94 (95% confidence interval, 1.19-3.16) for five chair stands (> or =20 s), compared to those with e3/3 status. At follow-up, associations between e4 status and incident poor performance on the chair stand test was significant. Associations with self-reported inability or need for help walking for 5 minutes or for climbing 15 steps were nonsignificant throughout. CONCLUSIONS: The ApoE e4 polymorphism is associated with a substantial excess of mobility limitation. The impact is detectable by performance testing, but not by self-reports. Poor results on mobility performance tests may provide a phenotype of ageing.