5.30 THE EFFECT OF CLOSED-LOOPED ACOUSTIC STIMULATION DURING SLEEP IN CHILDREN WITH AND WITHOUT ADHD: ENHANCING THE CONSOLIDATION OF REWARDED MEMORIES BY INCREASING SLOW-WAVE ACTIVITY?

Abstract

Objectives: Slow oscillations (SO) during slow-wave sleep foster the consolidation of declarative memory. Children with ADHD display deficits in the sleep-associated consolidation of declarative memory, possibly due to an altered function of SO. A recent study showed that the external induction of SO by transcranial direct current stimulation (tDCS) can normalize the sleep-dependent consolidation of declarative memory in children with ADHD. The present study aimed at enhancing SO activity using closed-looped acoustic stimulation during slow-wave sleep in children with ADHD. This method was proven to enhance endogenous SO activity during sleep and to foster sleep-dependent consolidation of declarative memory. Methods: Fourteen children with ADHD (aged 9-12 years) and 15 healthy children (same ages) participated in a double-blind, placebo-controlled study. Besides an adaptation night, children spent 2 experimental nights in a sleep lab, including 1 stimulation night and 1 sham night. Before sleep, children learned a set of word pairs; half of the word pairs were declared as high-rewarded (yielding a high monetary reward), while the other half was declared as low-rewarded (yielding only little monetary reward). In addition, a motor learning (serial reaction time) task was applied. After sleep, the retrieval took place on the next morning. Results: There were no differences in memory performance between children with and without ADHD in the sham condition. After stimulation, however, healthy children performed significantly better on high-rewarded memory items, compared to children with ADHD. In contrast, children with ADHD performed better on the motor learning task than healthy children. Conclusions: Here, we observed that the improvement of endogenous SO activity during sleep supported the consolidation of rewarded declarative memories in healthy children. No such effect was observed in children with ADHD. These data support the hypothesis that the function of slow-wave activity in memory consolidation is altered in ADHD. ADHD, SLP, COG