Methylphenidate and TBI in ADHD and co-occurring epilepsy and mental disorders: a self-controlled case series study

It is suggested that medication for attention-deficit hyperactivity disorder (ADHD) links to lower risk of traumatic brain injury (TBI). Little is known about whether the beneficial effect of methylphenidate is persistent in individuals with other comorbid mental disorders and epilepsy. We identified 90,634 participants who were less than 18 years old and diagnosed with ADHD from Taiwan's National Health Insurance Research Database (NHIRD) from January 1, 2000 to December 31, 2013. Cox proportional hazards models with hazard ratio (HR) and 95% confidence interval were conducted to compare the risks of TBI event between groups of ADHD-only and ADHD with co-occurring other mental disorders. Within-individual comparisons using a self-controlled case series study design were conducted using conditional Poisson regression models with relative incidence (RR) and 95% CI to examine the effect of methylphenidate on TBI with adjustment for medication of psychotropics and anticonvulsants. For children and adolescents with ADHD, we found comorbid mental disorders and epilepsy increase the risk of TBI, with HRs ranged from 1.21 to 1.75. For the effect of MPH, we found reduced risks for TBI in ADHD (RR = 0.83, 95% CI = 0.70-0.98). Similar results were found among individuals with co-occurring oppositional defiant disorders or conduct disorder, MDD, tic disorders and epilepsy. Methylphenidate treatment was linked to lower risk for TBI in patients with ADHD and the inverse association was persistent among those with other comorbid mental disorders and epilepsy.