Physical activity and Alzheimer disease course

Abstract

Objectives: To examine the association between physical activity (PA) and Alzheimer disease (AD) course.

Background: PA has been related to lower risk for AD. Whether PA is associated with subsequent AD course has not been investigated.

Methods: In a population-based study of individuals aged 65 years and older in New York who were prospectively followed up with standard neurologic and neuropsychological evaluations (every ~1.5 years), 357 participants i) were nondemented at baseline and ii) were diagnosed with AD during follow-up (incident AD). PA (sum of participation in a variety of physical activities, weighted by the type of activity [light, moderate, and severe]) obtained 2.4 (standard deviation [SD], 1.9) years before incidence was the main predictor of mortality in Cox models and of cognitive decline in generalized estimating equation models that were adjusted for age, gender, ethnicity, education, comorbidities, and duration between PA evaluation and dementia onset.

Results: One hundred fifty incident AD cases (54%) died during the course of 5.2 (SD, 4.4) years of follow-up. When compared with incident AD cases who were physically inactive, those with some PA had lower mortality risk, whereas incident AD participants with much PA had an even lower risk. Additional adjustments for apolipoprotein genotype, smoking, comorbidity index, and cognitive performance did not change the associations. PA did not affect rates of cognitive or functional decline.

Conclusion: Exercise may affect not only risk for AD but also subsequent disease duration: more PA is associated with prolonged survival in AD.

Figures

Figure 1

Flow chart describing sample.

Figure 2

Survival curves based on Cox analyses comparing Alzheimer's disease mortality in subjects belonging to each physical activity group (p for trend

Figure 3

GEE predicted cognitive z-scores (figure 3A) and GEE predicted function (ADLs) (figure 3B) (y-axis) over the course of follow-up in years (x-axis) separately for the none (grey solid line), some (black solid line) and much (dashed line) PA groups from a fully adjusted model. Lower cognitive z-scores and higher function scores indicate clinical worsening. Neither rates of cognitive (time × PA group interaction β = −0.004; p = 0.69) nor rates of functional (time × PA group interaction β = 0.063; p = 0.18) decline differed among PA groups.

Figure 3

GEE predicted cognitive z-scores (figure 3A) and GEE predicted function (ADLs) (figure 3B) (y-axis) over the course of follow-up in years (x-axis) separately for the none (grey solid line), some (black solid line) and much (dashed line) PA groups from a fully adjusted model. Lower cognitive z-scores and higher function scores indicate clinical worsening. Neither rates of cognitive (time × PA group interaction β = −0.004; p = 0.69) nor rates of functional (time × PA group interaction β = 0.063; p = 0.18) decline differed among PA groups.