Cognitive training linked to improved executive function in isolated REM sleep behavior disorder

The primary outcome was change in executive function measured at 6 weeks post-allocation and again at 6-month follow-up. At 6 weeks, the intervention group showed a medium-sized improvement in executive function compared to controls (Cohen's d = 0.500, 95% CI: 0.221–0.779), and this benefit persisted at 6 months, though with a smaller effect size (d = 0.397, 95% CI: 0.115–0.679). The trial was single-center and relatively small, and longer-term follow-up data are not yet available; the researchers note that the suitability of this approach for actual dementia prevention requires further investigation.

The CogTrAiL-RBD trial is notable for its focus on a prodromal population—people with iRBD face markedly elevated risk of Lewy body dementia, making this an ideal stage for preventive intervention. The cognitive training was adaptive (difficulty adjusting to performance) and multidomain (targeting multiple cognitive processes), paired with lifestyle guidance; both elements together produced the effect, so neither alone can be assumed responsible. The medium effect at 6 weeks (d = 0.500) is clinically meaningful but modest; the decline to a small effect at 6 months suggests the benefit may require ongoing engagement, though the effect did not disappear. A key limitation is that the study lasted only 6 months; longer-term follow-up is essential to know whether improved executive function in this window actually delays or prevents conversion to overt neurodegeneration. The waiting-list design means practice effects and motivation differences cannot be fully ruled out. iRBD is rare, limiting generalizability, but the feasibility demonstrated here opens a door to testing whether multidomain cognitive intervention might prevent cognitive decline in this high-risk group.