Suicide and depression in former contact sports participants: population-based cohort study, systematic review, and meta-analysis

Abstract

Background: Traumatic brain injury is associated with the future risk of depression and suicide, and this raises the possibility that former participants in sports characterised by low intensity repetitive head impact may also subsequently experience an increased burden of these mental health outcomes. Using new data from a cohort study integrated into a meta-analysis of the current evidence, we compared the occurrence of depression and suicide in former contact sports athletes against general population controls. Methods: The cohort study comprised 2004 retired male athletes who had competed internationally on an amateur basis for Finland between 1920 and 1965, and 1385 age-equivalent male general population controls. Former contact sports participants were drawn from soccer, boxing, or Olympic-style (non-professional) wrestling. During follow-up, cases of major depressive disorder and suicide were captured via linkage to mortality and hospitalisation registries. In a PROSPERO-registered (CRD42022352780) systematic review, we searched PubMed and Embase from their inception to October 31 2022 for reports of cohort studies of contact sports participation and later risk of depression and suicide that were published in English and reported standard estimates of association and variance. Study-specific estimates were aggregated using random-effect meta-analysis. The Newcastle-Ottawa Scale was used to appraise the quality of each study. Findings: In analyses of the Finnish cohort data, up to 45 years of health surveillance gave rise to 131 hospitalisations for major depressive disorder and 61 suicides. In survival analyses (hazard ratio [95% confidence interval]) adjusted for age and socioeconomic status, former boxers (depression: 1.43 [0.73, 2.78]; suicide: 1.75 [0.64, 4.38]), wrestlers (depression: 0.94 [0.44, 2.00]; suicide: 1.60 [0.64, 3.99]), and soccer players (depression: 0.62 [0.26, 1.48]); suicide: 0.50 [0.11, 2.16]) did not have statistically significantly different rates of major depressive disorder or suicide relative to general population controls. The systematic review identified 463 potentially eligible published articles, of which 7 met inclusion criteria. All studies sampled men and 3 were evaluated as being of high quality. After aggregating results from these retrieved studies with new data from the cohort study, we found that retired soccer players appeared to have a somewhat lower risk of depression (summary risk ratio: 0.71 [95% 0.54, 0.93]) relative to general population controls, while the rate of suicide was essentially the same (0.70 [0.40, 1.23]). Past participation in American football was associated with some protection against suicide (0.58 [0.43, 0.80]) but there were insufficient studies of depression for aggregation. All studies showed directionally consistent relationships and there was no indication of inter-study heterogeneity (I2=0%). Interpretation: Based on a small cluster of studies exclusively comprising men, retired soccer players had a lower rate of later depression, and former American football players had a lower risk of suicide. Whether these findings are generalisable to women requires testing. Funding: None.

Dementia risk factors in former contact sports participants: prospective cohort study

“…Asterisk denotes statistical significance at p<0.05. Previously published, 8 the results for depression are shown here for the purposes of comparison with other dementia risk factors.…”

“…Retired American footballers appear to have a higher prevalence of obesity and elevated blood pressure relative to the general population 6 but whether this observation is generalisable to other contact sports is uncertain. Indeed, erstwhile elite soccer players have a lower incidence of both alcohol-related disorders 7 and depression 8 at follow-up. Given the clear paucity of data on dementia risk factors in former contact sports participants, using general population controls as a comparator, we examined levels of nine dementia risk factors amongst retired elite boxers, wrestlers, and soccer players – all sports which have previously been linked to a higher burden of dementia.…”

Kumanu Tāngata: the aftermatch study – protocol to examine the health outcomes of high-level male rugby union players using linked administrative data

“…However, emerging literature using linked administrative health records has challenged this idea. In cohorts of Finnish contact sport athletes21 and professional Scottish18 and elite Swedish22 23 football players, athletes were shown to have no increased risk, and possibly even a reduced risk, of mood and substance use disorders as well as suicide relative to the general population.…”