Group effects of methylphenidate (MPH) dose on behavioural symptom reduction in attention-deficit/hyperactivity disorder (ADHD) show a linear effect (higher dose, larger reduction). For neurocognitive outcomes, dose effects are less studied and both linear and quadric dose-response curves have been reported.
Research presented at the 2019 European College of Neuropsychopharmacology Congress analysed 19 published placebo-controlled trials comparing fixed MPH dosages (low dose 0.10-0.39 mg/kg; medium doses 0.40-0.69 mg/kg; and high dose 0.70-0.99 mg/kg) with placebo.
MPH was superior to placebo in all analyses. Medium doses had the strongest effect on improving inhibition (Cohen's d=−0.32; 95% CI −0.48 to −0.15; P<.001 with a decrease in effect for high doses. cohen d low doses was ci to and p>
“This suggests that titration with an optimal result on ADHD symptoms does not ensure an optimal effect on neurocognitive outcomes,” said author, Karen Vertessen from VRIJE Universiteit Amsterdam in the Netherlands.
“Considering the complex relationship between ADHD symptoms, cognition and academic performance and the role of executive functioning in academic performance, these findings can be clinically relevant and consideration should be given to adding cognitive outcomes to the treatment outcomes of pharmacological therapy for ADHD,” she added.