Leisure-time physical activity has been related with a reduced risk of dementia and Alzheimer's disease (AD). The effects of occupational and commuting physical activity (physical activity at work and on the way to work) on cognitive health are still unclear. This study aimed to clarify the association between work-related physical activity and dementia/AD.
Participants of the Cardiovascular Risk Factors, Aging, and Dementia (CAIDE) study were derived from random, population-based samples previously studied in a survey carried out in 1972, 1977, 1982, or 1987. After an average follow-up of 21 years, 1449 individuals (73%) aged 65 to 79 years participated in the re-examination in 1998.
Neither occupational [Odds Ratio (OR) 1.45; 95% Confidence Intervals (CI) 0.66-3.17] nor commuting physical activity (OR 0.46; 95% CI 0.10-2.17) were associated with the risk of dementia or AD after adjustments for age, sex, education, follow-up time, locomotor symptoms, main occupation during life, income at midlife, leisure-time physical activity, other subtype of work-related physical activity, ApoE genotype, vascular disorders and the smoking status. There were also no interactions between work-related physical activity and the ApoE epsilon4 genotype, leisure-time physical activity or sex.
In this study, work-related physical activity was not found to be sufficient to protect against dementia and AD later in life. The lack of effect might be partly due to a residual confounding. Nevertheless, physical activity during leisure-time may be beneficial even for people who are physically active at work or when commuting.