Batty G David, Frank Philipp, Kujala Urho M, Sarna Seppo J, Valencia-Hernández Carlos A, Kaprio Jaakko
Department of Epidemiology and Public Health, University College London, London, UK.
Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland.
EClinicalMedicine. 2023 Jun 22;61:102056. doi: 10.1016/j.eclinm.2023.102056. eCollection 2023 Jul.
Although there is growing evidence that former professional athletes from sports characterised by repetitive head impact subsequently experience an elevated risk of dementia, the occurrence of this disorder in retired amateurs, who represent a larger population, is uncertain. The present meta-analysis integrates new results from individual-participant analyses of a cohort study of former amateur contact sports participants into a systematic review of existing studies of retired professionals and amateurs.
The cohort study comprised 2005 male retired amateur athletes who had competed internationally for Finland (1920-1965) and a general population comparison group of 1386 age-equivalent men. Dementia occurrence was ascertained from linked national mortality and hospital records. For the PROSPERO-registered (CRD42022352780) systematic review, we searched PubMed and Embase from their inception to April 2023, including cohort studies published in English that reported standard estimates of association and variance. Study-specific estimates were aggregated using random-effect meta-analysis. An adapted Cochrane Risk of Bias Tool was used to assess study quality.
In the cohort study, up to 46 years of health surveillance of 3391 men gave rise to 406 dementia cases (265 Alzheimer's disease). After adjustment for covariates, former boxers experienced elevated rates of dementia (hazard ratio: 3.60 [95% CI 2.46, 5.28]) and Alzheimer's disease (4.10 [2.55, 6.61]) relative to general population controls. Associations were of lower magnitude in retired wrestlers (dementia: 1.51 [0.98, 2.34]; Alzheimer's disease: 2.11 [1.28, 3.48]) and soccer players (dementia: 1.55 [1.00, 2.41]; Alzheimer's disease: 2.07 [1.23, 3.46]), with some estimates including unity. The systematic review identified 827 potentially eligible published articles, of which 9 met our inclusion criteria. These few retrieved studies all sampled men and the majority were of moderate quality. In sport-specific analyses according to playing level, there was a marked difference in dementia rates in onetime professional American football players (2 studies; summary risk ratio: 2.96 [95% CI 1.66, 5.30]) relative to amateurs in whom there was no suggestion of an association (2 studies; 0.90 [0.52, 1.56]). For soccer players, while dementia occurrence was raised in both erstwhile professionals (2 studies; 3.61 [2.92, 4.45]) and amateurs (1 study; 1.60 [1.11, 2.30]) there was again a suggestion of a risk differential. The only studies of boxers comprised former amateurs in whom there was a tripling in the rates of dementia (2 studies; 3.14 [95% CI 1.72, 5.74]) and Alzheimer's disease (2 studies; 3.07 [1.01, 9.38]) at follow-up compared to controls.
Based on a small number of studies exclusively sampling men, former amateur participants in soccer, boxing, and wrestling appeared to experience an elevated risk of dementia relative to the general population. Where data allowed comparison, there was a suggestion that risks were greater amongst retired professionals relative to amateurs in the sports of soccer and American football. Whether these findings are generalisable to the contact sports not featured, and to women, warrants examination.
This work was unfunded.
尽管越来越多的证据表明，从事以重复性头部撞击为特征运动的前职业运动员患痴呆症的风险随后会升高，但在退休的业余运动员（这是一个更大的群体）中这种疾病的发生情况尚不确定。本荟萃分析将一项对前业余接触性运动参与者队列研究的个体参与者分析的新结果整合到对退休职业运动员和业余运动员现有研究的系统评价中。
该队列研究包括2005名曾代表芬兰参加国际比赛的男性退休业余运动员（1920 - 1965年）以及1386名年龄相仿男性组成的一般人群对照组。通过关联的国家死亡率和医院记录确定痴呆症的发生情况。对于在PROSPERO注册（CRD42022352780）的系统评价，我们检索了PubMed和Embase自创建至2023年4月的文献，包括以英文发表的报告关联和方差标准估计值的队列研究。使用随机效应荟萃分析汇总特定研究的估计值。采用改编的Cochrane偏倚风险工具评估研究质量。
在队列研究中，对3391名男性长达46年的健康监测产生了406例痴呆症病例（265例阿尔茨海默病）。在对协变量进行调整后，与一般人群对照组相比，前拳击运动员患痴呆症（风险比：3.60 [95%置信区间2.46, 5.28]）和阿尔茨海默病（4.10 [2.55, 6.61]）的发生率升高。退休摔跤运动员（痴呆症：1.51 [0.98, 2.34]；阿尔茨海默病：2.11 [1.28, 3.48]）和足球运动员（痴呆症：1.55 [1.00, 2.41]；阿尔茨海默病：2.07 [1.23, 3.46]）的关联程度较低，一些估计值包括1。系统评价识别出827篇潜在符合条件的已发表文章，其中9篇符合我们的纳入标准。这些检索到的少数研究均以男性为样本，且大多数质量中等。在根据比赛水平进行的特定运动分析中，曾经的职业美式橄榄球运动员（2项研究；汇总风险比：2.96 [95%置信区间1.66, 5.30]）的痴呆症发生率与业余运动员相比存在显著差异（2项研究；0.90 [0.52, 1.56]），业余运动员中未显示出关联。对于足球运动员，虽然曾经的职业运动员（2项研究；3.61 [2.92, 4.45]）和业余运动员（1项研究；1.60 [1.11, 2.30]）患痴呆症的情况均有所增加，但同样存在风险差异的迹象。仅有的拳击运动员研究包括前业余运动员，与对照组相比，随访时痴呆症（2项研究；3.14 [95%置信区间1.72, 5.74]）和阿尔茨海默病（2项研究；3.07 [1.01, 9.38]）的发生率增加了两倍。
基于仅以男性为样本的少数研究，足球、拳击和摔跤项目的前业余参与者相对于一般人群似乎患痴呆症的风险升高。在数据允许比较的情况下，有迹象表明，在足球和美式橄榄球运动中，退休职业运动员相对于业余运动员的风险更大。这些发现是否适用于未涉及的接触性运动以及女性，有待进一步研究。
本研究无资金支持。
