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. Copyright (c) 2005 John Wiley & Sons, Ltd.