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Cross-sectional and prospective relationship between occupational and leisure time inactivity and cognitive function in an ageing population. The European Prospective Investigation into Cancer and Nutrition in Norfolk (EPIC-Norfolk) Study.

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Khaw, Kay-Tee 
Wareham, Nick 


Background: The current evidence for higher physical activity and better cognitive function and lower risk of dementia is strong but not conclusive. More robust evidence is needed to inform public health policy. We provide further insight to discrepancies observed across studies, reporting on habitual inactivity including that during work. Methods: We examined cross-sectional and prospective relationships of physical inactivity during leisure and occupation time, with cognitive performance using a validated physical activity index in a cohort of 8585 men and women aged 40-79 years at baseline (1993-1997) for different domains using a range of cognitive measures. Cognitive testing was conducted between 2006-2011 (including pilot phase 2004-2006). Associations were examined using multinomial logistic regression adjusting for socio-demographic and health variables as well total habitual physical activity. Results: Inactivity during work was inversely associated with poor cognitive performance (bottom tenth percentile of a composite cognition score); Odds Ratio (OR) = 0·68 (95% Confidence Interval (CI) 0.54, 0·86) P=0·001. Results were similar cross-sectionally; OR = 0·65 (95% CI 0·45, 0·93) P=0·02. Manual workers had increased risk of poor performance compared to those with an occupation classified as inactive. Inactivity during leisure time was associated with increased risk of poor performance in the cross-sectional analyses only.
Conclusions: The relationship between inactivity and cognition is strongly confounded by education, social class and occupation. Physical activity during leisure may be protective for cognition, but work related physical activity is not protective. A greater understanding of the mechanisms and confounding underlying these paradoxical findings is needed.



Ageing, cognitive function, physical inactivity, prospective cohort study, Adult, Aged, Aging, Cognition, Cross-Sectional Studies, Female, Humans, Leisure Activities, Male, Middle Aged, Neoplasms, Prospective Studies, Sedentary Behavior

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International Journal of Epidemiology

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Oxford University Press
Medical Research Council (G1000143)
Cancer Research Uk (None)
Medical Research Council (MC_UU_12015/1)
Department of Health (via National Institute for Health Research (NIHR)) (NF-SI-0617-10149)
Cancer Research Uk (None)
Medical Research Council (MR/N003284/1)
Cancer Research Uk (None)
Medical Research Council (G0500300)
Medical Research Council (G0401527)
MRC (MC_UU_00006/1)
Medical Research Council (G0401527/1)
This work was supported by the Medical Research Council, UK (MRC) (Ref: MR/N003284/1, MC-UU_12015/1 to N.W.); Cancer Research UK, (CRUK, Ref: C864/A8257) and NIHR, (Ref: NF-SI-0616–10090 to C.B.). The clinic for EPIC- orfolk 3HC was funded by Research into Ageing, now known as Age UK, (Grant Ref: 262). The pilot phase was supported by MRC (Ref: G9502233) and CRUK (Ref: C864/A2883)