Association of Concussion With an Increased Risk of Psychotic Disorders: A Retrospective Cohort Study

Head trauma has a well-documented association with increased incidence of psychiatric disorders, especially depression, anxiety, and post-traumatic stress disorder (PTSD). However, the relationship between traumatic brain injury (TBI) and subsequent psychotic disorders remains poorly characterized. Despite their relative rarity, psychotic disorders are highly debilitating, making clarification of this association clinically important, given the substantial public health burden of mild traumatic brain injury (mTBI). Whether this risk reflects mechanisms specific to head injury or trauma exposure more broadly remains unclear.

Using data from 3,023,268 propensity score-matched patients from 68 responding providers in the TriNetX US Collaborative Network, this retrospective cohort study compared patients with mTBI, defined by concussion or postconcussional syndrome (PCS), with patients with non-head trauma. Patients with psychotic outcomes before the index event were excluded. Outcomes included schizophrenia, schizotypal disorder, and brief psychotic disorder.

Over a 20-year follow-up period, 7,681 patients in the mTBI cohort and 3,178 patients in the non-head trauma cohort developed a psychotic disorder, corresponding to an absolute risk of 0.51% in the mTBI cohort and 0.21% in the non-head trauma cohort. mTBI was associated with a higher risk of psychotic disorder compared with non-head trauma (Risk Ratio (RR) 2.42, 95% CI 2.33-2.53, Odds Ratio (OR) 2.43, 95% CI 2.33-2.53). Kaplan-Meier analysis showed lower psychosis-free survival probability in the mTBI cohort at the end of follow-up (97.31% vs 98.83%), and Cox regression showed a significantly increased hazard of psychotic disorder (Hazard Ratio (HR) 2.125, 95% CI 2.04-2.22, p<0.001).

Although new-onset psychotic disorders were rare in both cohorts, patients with mTBI were more than twice as likely to develop psychotic disorders as patients with non-head trauma. These findings support an association between concussion/PCS and later psychotic illness and highlight the need for further work on mechanisms, risk modifiers, and early identification strategies.