Slow wave synchrony during NREM sleep tracks cognitive impairment in prodromal Alzheimer’s disease

This study revealed that the quality of deep sleep might be a key marker of cognitive decline in individuals with Alzheimer’s disease. As the disease advances from its early stages (amnestic mild cognitive impairment) to full-blown Alzheimer’s, the brain’s ability to produce synchronized slow waves during deep sleep decreases. These slow waves are essential for sleep-related memory consolidation. We observed a robust correlation between the reduction in slow-wave synchrony and worsening cognitive performance at the individual level. This suggests that brain activity during sleep, especially these slow waves, could be an important tool for monitoring the progression of Alzheimer’s disease