Monitoring Methylphenidate Dose Effects with AQT in Adults with Attention Deficit Disorder with Hyperactivity: A Validation Study

Background: Previous research introduced a model for monitoring dose effects with incremental increases of immediate-release methylphenidate. In the model, the monitoring process was performed within a three-day period, thereby reducing the potential wait time for dose optimization. Aims: To validate the use of processing-speed and efficiency measures to monitor the effects of treatment with immediate-release methylphenidate after a short period off medication, using a monitoring protocol described in previous research. Methods: A Quick Test of Cognitive Speed – AQT monitored the effects of incremental doses of immediate-release methylphenidate in 21 previously medicated adults with attention-deficits hyperactivity disorder - ADHD. Processing speed was evaluated with previously prescribed medication, no medication, low-dose (10/20 mg) and high-dose (20/40 mg) methylphenidate hydrochloride (Medikinet IR). Results: Twenty patients responded to treatment and one-way ANOVA indicated significant main effects for color, form and color-form naming. Post-hoc analyses showed statistical differences between the no- and high-dose medication conditions for color and form. For color-form naming, there was a significant difference between the no-medication and low-dose and no-medication and high-dose conditions. There was no statistical difference between the low- and high-dose conditions.. Conclusions: The results validated the previously tested dose-monitoring protocol. High-dose methylphenidate normalized cognitive speed for color-form naming, measures of attention, working memory and set shifting, and processing efficiency (i.e., shift cost) for all participants. The results suggest that the protocol may provide quantitative measures of aspects of cognition that may complement behavioral- and self-ratings.