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Centre for Policy on Ageing | |
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Physical activity, cognitive decline, and risk of dementia
— 28 year follow-up of Whitehall II cohort study | | Author(s) | Severine Sabia, Aline Dugravot, Jean-Francois Dartigues |
| Journal title | BMJ 2017;357:j2709, 22 June 2017 |
| Pages | 10 pp |
| Source | https://doi.org/10.1136/bmj.j2709 |
| Keywords | Exercise ; At risk ; Cognitive impairment ; Dementia ; Civil servants ; Living in the community ; Measurement ; Longitudinal surveys. |
| Annotation | The Whitehall II study is an ongoing cohort study of men and women originally employed by the British Civil Service in London-based offices. The authors tested hypotheses that physical activity in midlife is not associated with a reduced risk of dementia, and that the pre-clinical phase of dementia is characterised by a decline in physical activity. The physical activity of 10,308 participants aged 35-55 years at study inception (1985-88) was assessed. Exposures included time spent in mild, moderate to vigorous, and total physical activity assessed seven times between 1985 and 2013 and categorised as "recommended" if duration of moderate to vigorous physical activity was 2.5 hours per week or more. A battery of cognitive tests was administered up to four times from 1997 to 2013, and incident dementia cases (n=329) were identified through linkage to hospital, mental health services and mortality registers until 2015. Mixed effects models showed no association between physical activity and subsequent 15-year cognitive decline. Similarly, Cox regression showed no association between physical activity and risk of dementia over an average 27 year follow-up (hazard ratio in the "recommended" physical activity category 1.00, 95% confidence interval 0.80 to 1.24). For trajectories of hours per week of total, mild, and moderate to vigorous physical activity in people with dementia compared with those without dementia (all others), no differences were observed between 28 and 10 years before diagnosis of dementia. However, physical activity in people with dementia began to decline up to nine years before diagnosis (difference in moderate to vigorous physical activity -0.39 hours per week; P=0.05), and the difference became more pronounced (-1.03 hours per week; P=0.005) at diagnosis. This study found no evidence of a neuroprotective effect of physical activity. Previous findings showing a lower risk of dementia in physically active people may be attributable to reverse causation _ that is, due to a decline in physical activity levels in the pre-clinical phase of dementia. (OFFPRINT.) (RH). |
| Accession Number | CPA-170623001 A |
| Classmark | CEA: CA3: E4: EA: XM8: K4: 3R: 3J * |
Data © Centre for Policy on Ageing |
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| ...from the Ageinfo database published by Centre for Policy on Ageing. |
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