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

Background: The elevated dementia incidence in retired contact sport participants might be explained by a higher prevalence of established risk factors for the disease relative to the general population. Methods: In this cohort study, former elite participants active between 1920 and 1965 in soccer (N=303), boxing (N=281), and wrestling (N=318) were recruited using sports yearbooks and records of sports associations. Men in a population control group were identified using records from a compulsory medical examination (N=1712). All study members were linked to hospital registers (1970-2015) and self-completion questionnaires were circulated (1985, 1995) from which we captured data on nine established risk factors for dementia: hypertension and diabetes status, alcohol intake, loneliness, depressive symptoms, cigarette smoking, body weight, educational attainment, and physical activity. Results: There was little suggestion that former participants in contact sports had a higher prevalence of dementia risk factors relative to the general population. Rather, the balance of evidence was for more favourable risk factor levels in former athletes, as was particularly evident for ever having smoked cigarettes (range in odds ratios [95% confidence interval]: 0.32 [0.21, 0.48] for wrestling to 0.52 [0.36, 0.75] for soccer) and leisure-time physical activity (range in beta coefficients [95% confidence interval]: 1.34 [0.66, 2.02] for soccer to 1.80 [1.07, 2.52] for boxing). Conclusions: The increased dementia rates in retired contact sport participants evident in epidemiological studies is unlikely to be explained by the risk factors examined here. This implicates other characteristics of contact sports, including a history of repeated head impact.

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

Background: Former participants in sports characterised by low intensity repetitive head impact appear to have elevated rates of later dementia, but links with other psychological health outcomes such as depression and suicide are uncertain. We quantified the occurrence of these endpoints in former contact sports athletes against general population controls using new data from a cohort study and a meta-analysis. Methods: The cohort study comprised 2004 retired male athletes, who had competed internationally as amateurs for Finland across a range of sports, and 1385 general population controls. All study members were linked to mortality and hospitalisation registries. In the PROSPERO-registered systematic review (CRD42022352780), we searched PubMed and Embase to October 31 2022 for cohort studies that reported standard estimates of association and precision. Study-specific estimates were aggregated in a random-effect meta-analysis. The Newcastle-Ottawa Scale was used to appraise the quality of each study. Findings: In survival analyses of the Finnish cohort data, former boxers (depression: hazard ratio 1.43 [95% CI 0.73, 2.78]; suicide: 1.75 [0.64, 4.38]), Olympic-style 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 higher rates of major depressive disorder or suicide at follow-up relative to controls. In the systematic review, 7 cohort studies met inclusion criteria. After aggregating results with the Finnish cohort, retired soccer players appeared to have a lower risk of depression (summary risk ratio: 0.71 [0.54, 0.93]) relative to general population controls, while the rate of suicide was statistically the same across groups (0.70 [0.40, 1.23]). Past participation in American football seemed to be associated with some protection against suicide (0.58 [0.43, 0.80]) but there were insufficient studies of depression in this sport to facilitate aggregation. The aggregation of results from the soccer and American football 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 relative to comparator groups. Whether these findings are generalisable to women requires testing. Funding: The preparation of this manuscript was unfunded.

Dementia in former amateur and professional contact sports participants: population-based cohort study, systematic review, and meta-analysis.

Background: 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. Methods: 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. Findings: 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. Interpretation: 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. Funding: This work was unfunded.

Arrhythmias and heart rate variability during and after therapeutic hypothermia for cardiac arrest.

OBJECTIVE: To evaluate the effects of therapeutic hypothermia (HT) of 33 degrees C after cardiac arrest (CA) on cardiac arrhythmias, heart rate variability (HRV), and their prognostic value. DESIGN: Prospective, comparative substudy of a randomized controlled trial of mild HT after out-of-hospital CA, the European Hypothermia After Cardiac Arrest study. SETTING: Intensive care unit of a tertiary referral hospital (Helsinki University Hospital). PATIENTS: Seventy consecutive adult patients resuscitated from out-of-hospital ventricular fibrillation were randomly assigned either to therapeutic HT of 33 degrees C or normothermia. INTERVENTIONS: Patients randomized to HT were cooled with an external cooling device for 24 hours and then allowed to rewarm slowly during 12 hours. In the normothermia group, the core temperature was kept <38 degrees C by antipyretics and physical means. All patients received standard intensive care for at least 2 days. MEASUREMENTS AND MAIN RESULTS: Twenty-four hour ambulatory electrocardiography recordings were performed at 0-24 hours, at 24-48 hours, and at 14 days. The clinical outcome was assessed at 6 months after CA. The occurrence of premature ventricular beats was increased in the HT-treated group during the first two recordings, with no difference in the number of ventricular tachycardia or ventricular fibrillation episodes. All HRV values were significantly higher during the HT (p < 0.01), but no differences were observed 2 weeks later. In multivariate analysis, only shorter delay to restoration of spontaneous circulation (p = 0.009) and the sd of individual normal-to-normal intervals >100 msec of the 24-48-hour recording in the HT group (p = 0.018) predicted good outcome. CONCLUSIONS: The use of therapeutic HT of 33 degrees C for 24 hours after CA was not associated with an increase in clinically significant arrhythmias. Preserved 24 to 48-hour HRV may be a predictor of favorable outcome in patients with CA treated with HT.

Predictors of benzodiazepine discontinuation in subjects manifesting complicated dependence.

We described characteristics of subjects with benzodiazepine dependence that was typically complicated by harmful and hazardous alcohol use or high benzodiazepine doses, and assessed predictors of successful discontinuation of benzodiazepines for this group. Seventy-six patients who participated in a randomized clinical trial of two different gradual withdrawal treatment approaches were assessed. The trial was conducted between February 1995 and July 1999. The mean age +/- SD of subjects was 40.0 +/- 9.6 years, 55% were male, 38% were married or cohabiting, and 70% had received more than nine years of education. The median benzodiazepine dose was 35 mg/day (range 2.5-180) in diazepam equivalents. The median duration of benzodiazepine use was 84 (range 8-360) months. Subjects with lower benzodiazepine doses and no previous withdrawal attempts were more successful at benzodiazepine discontinuation. Cluster B personality/borderline personality disorder was associated with an inability to stop benzodiazepine use and with "dropping out" of treatment. Alcohol use-related disorders or other psychiatric diagnoses were not associated with outcome. Further studies on predictors of successful benzodiazepine discontinuation in different populations are required. Patients manifesting cluster B personality/borderline personality disorder and benzodiazepine dependence may need concomitant treatment for their personality disorders to benefit from benzodiazepine discontinuation treatment.