A comprehensive review analyzed the long-term health impacts of traumatic brain injury across 31 million participants, revealing associations with multiple adverse outcomes.

The study, published in Nature Mental Health, synthesized data from 24 systematic reviews and meta-analyses conducted between 2009 and 2023, encompassing primary research spanning from 1952 to 2022.

Investigators found relative risk (RR) estimates for traumatic brain injury (TBI) of any severity ranging from 1.35 for amyotrophic lateral sclerosis (ALS) to 4.16 for epilepsy. Severe TBI showed an elevated RR of 6.3 (95% confidence interval [CI] = 2.0–14.3) for attention-deficit/hyperactivity disorder (ADHD) in pediatric populations and 1.69 (95% CI = 1.3–2.2) for ALS. Mild TBI was linked with an RR of 1.18 (95% CI = 0.32–3.05) for ADHD and 2.06 (95% CI = 1.61–2.62) for depression.

The study highlighted additional findings, including a significant association between TBI and psychosis in pediatric populations (RR = 1.80, 95% CI = 1.11–2.93). Violence perpetration also demonstrated a notable RR of 1.62 (95% CI = 1.12–2.21). Population-attributable fraction calculations suggested TBI accounted for 27.5% of epilepsy cases and 7.3% of dementia cases.

Although dementia, violence, and ALS were supported by moderate-quality meta-analytical evidence, prediction intervals were significant only for violence perpetration and ALS in severe TBI. The overall evidence quality was limited, with 79.1% of reviews rated as critically low by AMSTAR 2 criteria, and no reviews achieving a high-quality rating.

The review identified the need for stratifying outcomes by TBI severity and highlighted research gaps, including the health impacts of TBI in survivors of intimate partner violence.

The study was registered with PROSPERO (CRD42023432255) and received support from the NIHR Oxford Health Biomedical Research Centre and Wellcome Trust Senior Research Fellowship. The authors declared no competing interests.