Department of Public Health and Primary Care, Institute of Public Health, University of Cambridge, Cambridge, UK.
MRC Epidemiology Unit, University of Cambridge School of Clinical Medicine, Cambridge, UK.
Int J Epidemiol. 2020 Aug 1;49(4):1338-1352. doi: 10.1093/ije/dyaa067.
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 into discrepancies observed across studies, reporting on habitual inactivity including that during work.
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 and 2011 (including a pilot phase 2004-2006). Associations were examined using multinomial logistic-regression adjusting for socio-demographic and health variables as well total habitual physical activity.
Inactivity during work was inversely associated with poor cognitive performance (bottom 10th 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 with 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.
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.
目前，体力活动水平较高与认知功能更好、痴呆风险更低之间的关联证据确凿，但还不具有结论性。需要更有力的证据来为公共卫生政策提供信息。我们进一步分析了观察到的研究差异，报告了包括工作期间在内的习惯性不活动情况。
我们使用经过验证的体力活动指数，在一个由 8585 名年龄在 40-79 岁的男性和女性组成的队列中，研究了闲暇时间和工作时间不活动与认知表现之间的横断面和前瞻性关系，使用了一系列认知测量方法来评估不同领域的认知表现。认知测试在 2006 年至 2011 年期间进行（包括 2004 年至 2006 年的试点阶段）。使用多项逻辑回归模型，在调整了社会人口统计学和健康变量以及总习惯性体力活动后，对关联进行了检验。
工作期间不活动与认知表现不佳（综合认知评分的第 10 个百分位数以下）呈负相关：比值比（OR）=0.68（95%置信区间（CI）0.54，0.86），P=0.001。横断面研究结果相似：OR=0.65（95%CI 0.45，0.93），P=0.02。与职业被归类为不活跃的人相比，体力劳动者认知表现不佳的风险增加。仅在横断面分析中，闲暇时间不活动与认知表现不佳的风险增加相关。
不活动与认知之间的关系受到教育、社会阶层和职业的强烈混淆。闲暇时间的体力活动可能对认知有保护作用，但与工作相关的体力活动没有保护作用。需要更深入地了解这些矛盾发现背后的机制和混淆因素。
