Risk of Mania After Methylphenidate in Patients With Bipolar Disorder

BACKGROUND: Bipolar disorder and attention-deficit/hyperactivity disorder are common comorbidities. Attention-deficit/hyperactivity disorder is commonly treated with stimulants (eg, methylphenidate), which, however, have been suggested to cause treatment-emergent mania in patients with bipolar disorder. Here, we assessed the risk of mania, depressive episodes, and psychiatric admissions after initiation of methylphenidate treatment in patients with bipolar disorder.METHODS: Using Danish health registries, we identified all individuals registered with a diagnosis of bipolar disorder from January 1, 2000, to January 1, 2018, who were treated with methylphenidate. We applied a 1-year mirror-image model to compare the occurrence of mania, depression, and psychiatric admissions in the period leading up to and after methylphenidate treatment initiation. We furthermore assessed the trend in these outcomes from 4 years before to 1 year after initiation of methylphenidate treatment.RESULTS: A total of 1043 patients with bipolar disorder initiated treatment with methylphenidate. The number of manic episodes decreased by 48% after methylphenidate treatment initiation (P = 0.01), both among patients using mood stabilizers (-50%) and among patients not using mood stabilizers (-45%). The number of manic episodes, however, peaked approximately 6 months before methylphenidate. The results were similar for the secondary outcomes.CONCLUSIONS: Initiation of methylphenidate treatment was not associated with an increased risk of mania in patients with bipolar disorder. A decrease in mania, depressive episodes, and psychiatric admissions was observed after methylphenidate. However, these decreases seemed to be driven by regression to the mean after clinical deterioration preceding methylphenidate treatment, rather than by the methylphenidate treatment itself.