Does Methylphenidate Improve Inhibition and Other Cognitive Abilities in Adults with Childhood-Onset ADHD?

Abstract

We examined the effect of methylphenidate (Mph) on inhibition and several other cognitive abilities in 43 adults with Attention Deficit Hyperactivity Disorder (ADHD) by use of Conners’ Continuous Performance Test (CPT) and the Change Task (ChT), an extension of the Stop Signal Test (SST). In a double blind, cross-over, placebo controlled study with Mph, tests were administered during the third week of individually titrated treatment with Mph (maximum dose 1 mg / kg / day) and during the third week of treatment with placebo. We established large medication effects for commission errors, standard error of mean reaction time, and attentiveness on the CPT, as well as moderate medication effects for mean reaction time on the CPT and response re-engagement speed on the ChT. For Stop Signal Reaction Time (SSRT) on the ChT, we also established large effects of Mph, but only in a group of participants who showed slow SSRTs on placebo. Mph indeed ameliorates inhibition, which is the core problem of ADHD, and certain other cognitive abilities in adults with ADHD.

This research was supported by grants from Mental Health Institute GGZ Delfland, Health Insurance Company DSW, Nationaal Fonds Geestelijke Volksgezondheid (National Foundation for Mental Health), and De Hersenstichting (Brain Foundation). We thank Alex de Jager, Judith Rietjens, and Susan ter Linden for their help in collecting the data. We thank the Board of Scientific Activities of the Reinier de Graaf Hospital in Delft for their financial contribution to the preparation of the study medication. We thank Paul van der Linden for his help with the randomization procedure.

Notes

This research was supported by grants from Mental Health Institute GGZ Delfland, Health Insurance Company DSW, Nationaal Fonds Geestelijke Volksgezondheid (National Foundation for Mental Health), and De Hersenstichting (Brain Foundation). We thank Alex de Jager, Judith Rietjens, and Susan ter Linden for their help in collecting the data. We thank the Board of Scientific Activities of the Reinier de Graaf Hospital in Delft for their financial contribution to the preparation of the study medication. We thank Paul van der Linden for his help with the randomization procedure.