The Connection Between Alzheimer’s Disease and Circadian Rhythms
The relationship between Alzheimer’s disease and our brain’s operational routine has been further elucidated by a recent study that delves into the daily rhythm of genetic activity in different cell types. This rhythm, known as the circadian rhythm, dictates when we wake up, when we sleep, and ensures that various biological processes run smoothly on a 24-hour cycle.
Disrupted sleep patterns have previously been associated with Alzheimer’s disease. To gain a deeper understanding of this connection, researchers from the Washington University School of Medicine investigated the circadian rhythms of genes related to the risk factors of Alzheimer’s.
The study involved comparing the brains of mice with Alzheimer’s-like conditions to those of healthy mice of varying ages. The expression of key genes in two specific cell types, astrocytes, which support neurons, and microglia, immune cells, was measured. These findings were then validated in human tissue samples.
Neurologist Erik Musiek from WashU Medicine explains, “There are 82 genes associated with Alzheimer’s disease risk, and approximately half of these genes are regulated by the circadian rhythm. This discovery opens up avenues for identifying therapeutic treatments to modulate these genes and potentially halt the progression of the disease.”
One significant finding of the study is that the circadian rhythm influences many genes linked to Alzheimer’s pathology, potentially disrupting the brain’s normal functioning, especially its ability to clear out toxic waste. The mice in the study were genetically modified to develop amyloid-beta protein plaques in the brain, a characteristic feature of Alzheimer’s.
It remains unclear whether these plaques disrupt the circadian rhythm or if an altered rhythm triggers the formation of plaques. However, researchers suspect that the disrupted clocks may play a role in the development of Alzheimer’s disease.
Alzheimer’s is known to disrupt the body’s daily rhythms, with symptoms such as increased confusion in the late afternoon or early evening, a phenomenon referred to as sundowning. The study highlights the importance of circadian rhythms in gene expression in understanding glial function in health, Alzheimer’s, and aging.
Approximately one-fifth of the genes in the human genome are believed to alter their expression in response to the body’s internal clocks, impacting crucial processes like digestion, sleep, and tissue repair. By observing daily fluctuations in brain cells affected by neurodegeneration, researchers can explore strategies to counteract the effects of Alzheimer’s pathology.
Further research is needed to fully comprehend the mechanisms at play, but the goal is to manipulate the circadian system to prevent amyloid accumulation and other aspects of Alzheimer’s disease. By optimizing the circadian rhythm, researchers hope to develop interventions that could potentially mitigate the progression of Alzheimer’s.
The findings of this study were published in Nature Neuroscience, shedding light on the intricate interplay between circadian rhythms and Alzheimer’s disease.
