Efficacy of single low-dose methylphenidate administration in adult ADHD patients according to psychometric assessment

Attention deficit hyperactivity disorder (ADHD) is a chronic disabling disorder that often persists to adulthood (70%). Methylphenidate (MPH) is reported efficient in adults suffering from ADHD. MPH dosage of ∼0.5mg/Kg is common in children and adolescents. MPH dosage in adults is not determined and upper limit of 1mg/kg⁽¹⁾ was recommended. Objective: To evaluate the efficacious dosage of MPH in adults. Method: Adult ADHD/ADD patients who responded to MPH, according to the Test of Variables of Attention (T.O.V.A), were included. Response was estimated by repeating T.O.V.A.⁽²⁾. The dose, 15mg/20mg, was weight dependent (</≥80Kg). Results: 42/47 diagnosed adults had good response to MPH. Mean age 31.8±9.0, M:F ratio 21:21, ADHD/ADD 20:22. Highest dose 0.35 mg/Kg. Mean dosage was 0.2±0.05mg/Kg with a significant improvement in all T.O.V.A. scores: ADHD scores (p<0.0001); Standard Scores (p 0.02-0.001). The most effective dosage was 0.2-0.25mg/Kg (p≤0.001). Commission score, which correlates to impulsivity, showed the least improvement under MPH treatment, and was aggrevated at higher doses (T= -0.16, p=0.88). Conclusions: Low doses of MPH seem to be efficient in adults according to the improvement in T.O.V.A., while higher dosages may correlate with side effects.