Alzheimer's disease significantly disrupts daily routines, with symptoms such as sleep disturbances and increased confusion during the evening hours, known as "sundowning." Recent research from the Washington University School of Medicine in St. Louis has shed light on the intricate relationship between Alzheimer's disease and circadian rhythms—the body's internal clock that regulates sleep and other biological cycles.
The study, published in Nature Neuroscience on October 23, reveals that Alzheimer's disrupts circadian rhythms within specific brain cells, which in turn affects the expression patterns of hundreds of genes critical for brain function. Lead researcher Dr. Erik S. Musiek noted that approximately half of the 82 genes linked to Alzheimer's risk are influenced by circadian rhythms. In mice engineered to exhibit Alzheimer’s-like symptoms, these genes failed to maintain their normal daily activity patterns.
Disruptions in sleep, a common issue for caregivers of Alzheimer’s patients, may exacerbate the disease's progression. Musiek pointed out that disturbances in sleep can begin years before cognitive decline is apparent, leading to increased stress for both patients and caregivers.
The research team monitored gene activity in mice with amyloid plaques, a hallmark of Alzheimer's, over a 24-hour period. They found that amyloid deposits significantly disrupted the normal rhythms of genes in microglia and astrocytes—two types of brain cells essential for waste clearance and neuronal communication.
The findings suggest that therapies aimed at stabilizing circadian rhythms in these cell types may offer new avenues for treatment. Musiek emphasized the potential for manipulating the circadian system to mitigate amyloid accumulation and other Alzheimer’s-related issues, although further research is needed to fully explore this approach. The study received funding from several National Institutes of Health agencies, although the authors clarified that the content does not necessarily reflect the agencies' official views.