Background: To inform public health interventions, further investigation is needed to identify: (1) frequency/intensity of everyday physical activity (PA) needed to reduce dementia risk; (2) whether post-diagnosis reduction in PA is associated with cognitive outcomes in people with dementia.
Methods: Data from 11,391 men and women (aged ≥50) were obtained from the English Longitudinal Study of Ageing cohort. Assessments were carried out at baseline (2002-2003) and at biannual follow-ups (2004-2013).
Results: Older adults who carried out moderate to vigorous activity at least once per week had a 34%-50% lower risk for cognitive decline and dementia over an 8-10 year follow-up period. From pre- to post-dementia diagnosis, those who decreased PA levels had a larger decrease in immediate recall scores, compared to those who maintained or increased PA levels (analyses were adjusted for changes in physical function).
Conclusion: PA was associated with cognitive outcomes in a dose-dependent manner. Reduction in PA after diagnosis was associated with accelerated cognitive decline and maintaining PA may reduce symptom progression in dementia.
Keywords: Alzheimer's disease; cognitive functioning; epidemiology (dementia); other dementias; physical activity.