Risk factors for mental disorders following mild traumatic brain injury in young adults: a retrospective cohort study

Abstract Purpose To identify demographic and clinical risk factors associated with developing new mental-health diagnoses within one year after mild traumatic brain injury (mTBI) in young adults. Methods This retrospective cohort study used linked hospital and community electronic health records from a tertiary district referral hospital and an integrated payer-provider organization. Adults aged 18–45 years presenting with mTBI (Glasgow Coma Scale score 14–15) between 2000 and 2020 were included. Patients admitted to the intensive care unit or lacking continuous follow-up were excluded. Univariable analyses compared demographic, clinical, and psychiatric characteristics between individuals with and without new mental-health diagnoses (defined using ICD-9 codes). Multivariable logistic regression with generalized estimating equations was used to estimate adjusted odds ratios (ORs) for independent risk factors. Secondary outcomes included 12-month emergency-department visits, hospitalizations, and inpatient days. Results A total of 9,835 mTBI events among 8,985 unique patients were analyzed. Within one year of injury, 538 events (5.5%) were followed by a new mental-health diagnosis. Patients with new diagnoses were older, more likely to have a prior TBI (56% vs 19%; p = 0.010), and more frequently hospitalized from the emergency department (22% vs 9.9%; p < 0.001). In multivariable analysis, risk was independently associated with prior TBI (one prior injury OR 3.90, 95% CI 2.96–5.14; ≥ 2 injuries OR 6.37, 95% CI 5.00–8.12), hospitalization at the index visit (OR 1.79, 95% CI 1.18–2.71), and pre-existing mental-health history (OR 1.84, 95% CI 1.49–2.28). Conclusion Young adults with previous TBI, prior psychiatric history, or hospitalization after mTBI are at increased risk for developing new mental-health disorders. Early identification of these high-risk subgroups could guide structured follow-up and preventive mental-health interventions to reduce the long-term psychosocial burden of mTBI.