Sulforaphane Adjunct to Methylphenidate for Attention-deficit/Hyperactivity Disorder: A Randomized, Double-blind, Placebo-controlled Trial

Objectives: Available treatment strategies for attention-deficit/hyperactivity disorder (ADHD) encounter significant limitations and, thus, necessitate novel therapeutic approaches. In this regard, this study investigated the effects of sulforaphane due to its neuroprotective, anti-inflammatory, and antioxidant properties. Methods: Seventy ADHD outpatients aged 6 to 11 were equally assigned to receive methylphenidate (0.3 to 1.5 mg/kg/d) plus either sulforaphane 30 mg/d or matched placebo for 8 weeks. The teacher and parent ADHD rating scale (ADHD-RS) was used to assess their symptoms at baseline and weeks 4 and 8. The patients were also evaluated for side effects. Results: Thirty-two patients in the sulforaphane group and 31 in the placebo group completed the study with comparable baseline demographic and clinical characteristics ( P s>0.05). There were significant time-treatment interaction effects on the ADHD-RS total, inattention, and hyperactivity-impulsivity scores rated by teachers ( =0.245, 0.203, and 0.246, respectively) and parents ( =0.265, 0.283, and 0.159, respectively). Affirmatively, their reductions were significantly greater in the sulforaphane group until the endpoint rated by teachers (Cohen d s=1.192, 1.055, and 1.220, respectively) and parents (Cohen’s d s=1.344, 1.446, and 0.966, respectively). Better response to treatment (≥40% reduction in ADHD-RS total scores), robust improvement (≥50% reduction in ADHD-RS total scores), and remission (an ADHD-RS total score of ≤18) rates were obtained in the sulforaphane group until the endpoint ( P s<0.001). The side effect frequencies were comparable between the groups ( P s>0.05). Conclusions: Sulforaphane adjunct to methylphenidate was beneficial for inattention, hyperactivity-impulsivity, and total symptoms of children with ADHD safely and tolerably.