Motor memory consolidation processes in young female adults with ADHD may be less susceptible to interference

Young adults with Attention Deficit Hyperactivity Disorder (ADHD) may have an atypical procedural ("how to") memory consolidation phase, after practicing a movement sequence, with smaller gains in speed and some costs in accuracy, compared to typical peers, at 24h post-training. Here we tested the susceptibility of performance gains retained after motor practice by young female adults with (N=16) and without (N=16) ADHD to post-training interference. Participants were trained on the finger-to-thumb opposition sequence learning task with performance speed and accuracy recorded before training, immediately after, and at 24h post-training. Two hour after the initial training, participants practiced a second, similarly constructed but differently ordered sequence of movements. Typical young adults showed a significant interference effect, with only the performance of the second sequence showing robust gains in speed, with no costs in accuracy, in the 24h post-training consolidation phase. Participants with ADHD showed only small additional speed gains in the post-training consolidation phase but for both sequences. Altogether these results suggest that motor memory consolidation processes in young adults with ADHD may be less susceptible to interference compared to typical peers.