The Use of Brexpiprazole Combined With a Stimulant in Adults With Treatment-Resistant Attention-Deficit/Hyperactivity Disorder

Abstract Background This is the first controlled pharmacologic study in either adults or children with uncomplicated, treatment-resistant attention-deficit/hyperactivity disorder (ADHD). This study augmented stimulant therapy with the atypical antipsychotic brexpiprazole. The Food and Drug Administration preapproved primary outcome measure (Conners' Adult ADHD Rating Scale [CAARS]) showed no drug-placebo differences. Often studies showing no efficacy on the prestudy, defined primary outcome variable go unpublished. While this is decried, publishing studies with equivocal results remains rare. This reanalysis highlights trends in secondary measures having implications for treatment and research regarding treatment resistant ADHD. Methods Initially, 559 stimulant-naive and 174 prior stimulant nonresponders received methylphenidate osmotic-release oral system, dexmethylphenidate hydrochloride, lisdexamfetamine, or mixed amphetamine salts. After 5 weeks, 168 stimulant-naive patients and 68 prior stimulant nonresponders who failed treatment were randomized to brexpiprazole or placebo in a 2:1 ratio while the remaining were on the stimulant. Outcome was measured with the CAARS, Montgomery-Asberg Depression Rating Scale, Beck Depression Inventory, Clinical Global Impression, and the Wender-Reimherr Adult Attention Deficit Disorder Scale (WRAADDS). The WRAADDS contains 2 factors: attention and emotional dysregulation. Results Stimulant-naive patients showed no improvement with adjunctive brexpiprazole. Prior stimulant nonresponders displayed no brexpiprazole effect on the CAARS, Montgomery-Asberg Depression Rating Scale, or Beck Depression Inventory. In contrast, the WRAADDS detected a trend in treatment benefit, primarily through emotional dysregulation symptoms. Adverse effects on brexpiprazole and placebo were equivalent. Conclusions Brexpiprazole might be effective in ADHD adults who are nonresponders to 2 or more stimulants. Future trials in treatment-resistant ADHD should use a 1:1 randomization and use a measure of ADHD symptoms that includes emotional dysregulation.