Disrupted circadian rhythms in cognitively normal adults have been found to be associated with higher subsequent amyloid-beta levels, according to recent prospective data. This relationship was particularly strong in individuals who carry the APOE4 gene. The findings remained consistent even after excluding participants with baseline Alzheimer’s pathology.
Researchers conducted a study involving 319 participants in the Rotterdam study who did not have a diagnosis of dementia at baseline. The participants were followed up for a mean of 7.8 years, during which amyloid burden on PET scans was measured. The study revealed that higher daily variability at baseline, indicating fragmented 24-hour activity rhythms, was linked to increased PET amyloid burden 8 years later. This association held true even after adjusting for age, sex, APOE4 status, and other relevant factors.
The relationship between disrupted circadian rhythms and higher amyloid levels was found to be stronger in individuals who carried the APOE4 gene. This suggests that genetic factors may play a role in how circadian disruption impacts amyloid pathology in the brain.
This study adds to the existing evidence that circadian disruption may contribute to an increased risk of dementia, particularly Alzheimer’s disease. The findings indicate that fragmented 24-hour activity rhythms could be a risk factor, rather than a consequence, of Alzheimer’s pathology. It underscores the importance of further research in understanding the link between sleep patterns and neurodegenerative diseases.
Matthew Pase, PhD, from Monash University, highlighted the potential role of sleep dysfunction in the development of Alzheimer’s disease and dementia. Improving sleep quality may be a strategy to lower dementia risk, although sleep is not currently listed as one of the key risk factors that can be modified to prevent or delay dementia.
The study had some limitations, including the use of actigraphy to assess sleep and activity rhythms. While actigraphy has been shown to have fair associations with polysomnography, it may not capture all aspects of sleep quality accurately. Additionally, the participants only underwent one PET scan, limiting the ability to conduct longitudinal analyses.
Disrupted circadian rhythms in cognitively normal adults were found to be linked to higher subsequent amyloid-beta levels, particularly in APOE4 carriers. This study sheds light on the potential impact of sleep patterns on amyloid pathology and dementia risk. Further research is needed to explore the underlying mechanisms and to develop strategies to mitigate the effects of circadian disruption on brain health.
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