Department of Epidemiology and Public Health, University College London, London, UK; Clinicum, Department of Public Health, Faculty of Medicine, University of Helsinki, Helsinki, Finland; Finnish Institute of Occupational Health, Helsinki and Turku, Finland.
Clinicum, Department of Public Health, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
Alzheimers Dement. 2018 May;14(5):601-609. doi: 10.1016/j.jalz.2017.09.016. Epub 2017 Nov 21.
Higher midlife body mass index (BMI) is suggested to increase the risk of dementia, but weight loss during the preclinical dementia phase may mask such effects.
We examined this hypothesis in 1,349,857 dementia-free participants from 39 cohort studies. BMI was assessed at baseline. Dementia was ascertained at follow-up using linkage to electronic health records (N = 6894). We assumed BMI is little affected by preclinical dementia when assessed decades before dementia onset and much affected when assessed nearer diagnosis.
Hazard ratios per 5-kg/m increase in BMI for dementia were 0.71 (95% confidence interval = 0.66-0.77), 0.94 (0.89-0.99), and 1.16 (1.05-1.27) when BMI was assessed 10 years, 10-20 years, and >20 years before dementia diagnosis.
The association between BMI and dementia is likely to be attributable to two different processes: a harmful effect of higher BMI, which is observable in long follow-up, and a reverse-causation effect that makes a higher BMI to appear protective when the follow-up is short.
中年后期的体重指数（BMI）较高被认为会增加痴呆的风险，但在痴呆前临床阶段的体重减轻可能会掩盖这种影响。
我们在 39 项队列研究的 1349857 名无痴呆症参与者中检验了这一假设。在基线评估 BMI。使用与电子健康记录的链接（N=6894）在随访中确定痴呆。我们假设，当 BMI 在痴呆发病前几十年评估时，对临床前痴呆的影响较小，而当在诊断前更接近时，影响较大。
BMI 每增加 5kg/m2，痴呆的风险比分别为 0.71（95%置信区间=0.66-0.77）、0.94（0.89-0.99）和 1.16（1.05-1.27），当 BMI 在痴呆诊断前 10 年、10-20 年和>20 年评估时。
BMI 与痴呆之间的关联可能归因于两个不同的过程：较高 BMI 的有害影响，这在长期随访中是可见的，以及反向因果关系，当随访时间较短时，较高的 BMI 似乎具有保护作用。
