Relationship of exercise and other risk factors to depression of Alzheimer's disease: the LASER‐AD study

BACKGROUND: Depression is common in Alzheimer's disease (AD; 5-35%). It is associated with increased disability, cost of care and carer burden. Exercise is known to be associated with a lower prevalence of depression across the age range but little is known about its relationship to depression in AD. AIMS: To investigate exercise and putative risk factors for depression in a community based sample of people with AD representative of the range of cognitive impairment found in the population with dementia. METHODS: Information was collected from 224 people with AD and their caregiver using standardised cognitive, psychological and behavioural instruments. Exercise levels were classified into three categories: absent, moderate, and vigorous, using the previous two weeks exercise levels to confirm regularity and recency. RESULTS: 9/51 (17.6%) depressed participants took exercise compared with 76/173 (43.9%) non-depressed [odds ratio (OR)=2.9, confidence interval (CI)=1.5-5.6, p=0.001]. Not taking part in other activities (hobbies and interests) was associated with depression but less so than lack of exercise. Independent predictors of depression were: lack of exercise (p <0.001, OR=3.4, CI = 1.7-7.2), taking cholinesterase inhibitors (p <0.05, OR=2.4, CI = 1.2-4.9) and having less involvement in hobbies or interests (p <0.05, OR = 1.2, CI = 1.0-1.5). CONCLUSION: None of the traditional risk factors for depression in older people were associated with depression in AD. Taking regular exercise may protect against depression in AD.