The findings of a study in the Journal of Clinical Psychiatry suggest that the presence of certain symptoms in a cluster referred to as “sluggish cognitive tempo” may predict the efficacy of methylphenidate, the most commonly prescribed medication for attention-deficit/hyperactivity disorder (ADHD) in the world.
Sluggish cognitive tempo is a symptomatology most frequently exhibited by patients with the combined or inattentive ADHD subtypes. These symptoms include sluggishness, excessive daydreaming, and underactivity.
The investigators recruited 171 stimulant-naive children with ADHD through advertisement (ClinicalTrials.gov identifier: NCT01727414). The participants were age 7 to 11 years and exhibited either the inattentive (n=126) or combined presentation (n=45) of ADHD, as defined by the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition. Parents completed the Diagnostic Interview Schedule for Children. Participants’ teachers completed the Vanderbilt ADHD Diagnostic Teacher Rating Scale, which includes a rating of sluggish cognitive tempo.
During the 4-week, double-blind, randomized, controlled trial, children were randomly assigned to 1 of 6 dosing schedules with 3 active weeks. Participants weighing <25 kg were assigned either 18 mg/d, 27 mg/d, or 36 mg/d. Children weighing >25 kg had the possibility of being assigned to a 54 mg/d group instead of 36 mg/d, with a mean maximum dose of 1.57 mg/kg/d for participants overall.
Analyses suggested that children with an elevated sluggish/sleepy factor were more likely to be methylphenidate nonresponders or placebo responders (P =.04). Subtype and excessive daydreaming had no apparent relationship to response.
Participants were categorized as nonresponders (n=10) or placebo responders (n=26) if their symptom severity did not change throughout the trial, or if their symptoms improved most notably during a placebo week. The remaining 132 participants were designated methylphenidate responders.
Researchers have yet to identify any reliable predictors of methylphenidate response. Although the study’s findings were novel, the authors noted certain improvements that could be made to its design, including a longer study duration, collection of data on sluggish cognitive tempo from parents, and a greater proportion of participants with the combined subtype for the sake of generalizability.
Froehlich T, Becker S, Nick TG, et al. Sluggish cognitive tempo as a possible predictor of methylphenidate response in children with ADHD: a randomized controlled trial. J Clin Psychiatry. 2018;79(2):17m11553.