Effect of medication on risk of traumatic brain injury in patients with bipolar disorder: A nationwide population-based cohort study

Background: Increased traumatic brain injury (TBI) risk was found in patients with bipolar disorder (BPD). Whether the medications for BPD and dosage moderate the risk of TBI is not clear. Aim: This study aimed to determine whether an association exists between BPD and TBI and whether the prescription of psychotropics moderates TBI risk. Methods: A total of 5606 individuals who had received diagnoses of BPD between January 1, 1997 and December 31, 2013 and 56,060 matched controls without BPD were identified from Taiwan’s National Health Insurance Research Database. Cases and controls were followed until the date of TBI diagnosis. Results: BPD was associated with a high risk of TBI (adjusted hazard ratio (aHR): 1.85; 95% CI: 1.62–2.11). Patients with BPD, with or without a history of psychiatric hospitalization, had increased risks of TBI (aHR: 1.94, 95% CI: 1.57–2.4 and aHR: 1.82, 95% CI: 1.55–2.1, respectively). The prescription of typical antipsychotics (0 < defined daily dose (DDD) < 28: hazard ratio (HR) = 1.52, 95% CI: 1.19–1.94; ⩾28 DDD: HR = 1.54, 95% CI: 1.15–2.06) and tricyclic antidepressants (TCAs) (0 < DDD < 28: HR = 1.73, 95% CI: 1.26–2.39; ⩾28 DDD: HR = 1.52, 95% CI: 1.02–2.25) was associated with higher TBI risk. Patients receiving higher doses of benzodiazepines (BZDs) (cumulative dose ⩾28 DDD) had a higher TBI risk (HR = 1.53, 95% CI: 1.13–2.06). Conclusion: Patients with BPD have a higher risk of TBI. The use of typical antipsychotics, TCAs, or high-dose BZDs increases the risk of TBI in BPD.