The consolidation of a motor skill in young adults with ADHD: Shorter practice can be better.

Practice on a given sequence of movements can lead to robust procedural memory (skill). In young adults, in addition to gains in performance accrued during practice, speed and accuracy can further improve overnight; the latter, delayed, 'offline', gains are thought to emerge when procedural memory consolidation processes are completed. A recent study suggested that female college students with ADHD show an atypical procedural memory consolidation phase, specifically, gaining speed but losing accuracy, overnight. Here, to test if this accuracy loss reflected a cost of overlong training in adults with ADHD, we compared the performance of female college students with (N=16) and without (N=16) ADHD, both groups given a shorter training protocol (80 rather than the standard 160 task repetitions). Speed and accuracy were recorded before training, immediately after, and at 24-h and 2 weeks post-training. The shortened practice session resulted in as robust within-session gains and additional overnight gains in speed at no costs in accuracy, in both groups. Moreover, individuals with ADHD showed as robust speed gains and retention as in the longer training session, but the costs in accuracy incurred in the latter were eliminated. The shortening of practice sessions may benefit motor skill acquisition in ADHD.