A US longitudinal population-based cohort study suggests that chronic insomnia, especially with reduced sleep, is a risk factor for cognitive decline and adverse brain health in older adults. Researchers followed cognitively unimpaired participants who underwent annual neuropsychological testing and brain imaging (amyloid-PET and MRI for white matter hyperintensities [WMH]) over a median of 5.6 years. Among 2,750 participants (mean age 70.3 years, 49.2% female), insomnia was associated with faster cognitive decline, a 40% increased risk of incident cognitive impairment, and worse baseline brain health, particularly in those who also reported reduced sleep duration. Specifically, insomnia with reduced sleep was linked to poorer cognitive performance, higher WMH burden, and greater amyloid accumulation, while insomnia with increased sleep was associated with lower WMH burden, possibly reflecting symptom remission. However, insomnia was not associated with the rate of WMH or amyloid progression over time, and hypnotic use showed no significant effect on cognition or dementia risk. The findings are consistent with previous research and support a bidirectional relationship between insomnia and cognitive decline. Source: https://www.neurology.org/
