Research has shown a potential link between disrupted circadian rhythms in cognitively normal adults and increased levels of amyloid-beta, a biomarker associated with Alzheimer’s disease. These findings shed light on the importance of healthy sleep patterns in reducing the risk of developing dementia.
A study conducted by Julia Neitzel, PhD, and colleagues at Erasmus University Medical Center in Rotterdam, the Netherlands, revealed that higher daily variability in activity rhythms was linked to higher PET amyloid burden 8 years later. The relationship was even stronger in APOE4 carriers, a genetic risk factor for Alzheimer’s disease.
The literature on sleep and Alzheimer’s pathology has been inconsistent, with some studies suggesting a bidirectional relationship between the two. Neitzel’s study, however, controlled for Alzheimer’s pathology at baseline and still found an association between disrupted circadian rhythms and Alzheimer’s PET burden at follow-up. This indicates that fragmented sleep patterns may be a risk factor for Alzheimer’s disease.
According to the Lancet Commission, modifying certain key risk factors could prevent or delay up to 40% of dementia cases. While sleep is not currently included as one of these factors, the growing evidence linking circadian disruption to dementia risk suggests that improving sleep quality could be a potential strategy for lowering dementia risk.
The study by Neitzel and colleagues included 319 participants from the Rotterdam study who were free of dementia at baseline. While higher activity rhythm fragmentation was associated with more severe amyloid pathology at follow-up, other measures of sleep duration or quality did not show a strong relationship with amyloid burden. The researchers noted that actigraphy studies are typically smaller due to the burden of wearing activity monitors for extended periods.
Longitudinal analyses in the study were limited by having only one PET scan per participant. While actigraphy is a useful tool for assessing sleep patterns, the gold standard for measuring sleep is polysomnography. Further research could explore the potential impact of sleep apnea on Alzheimer’s risk, as it was not fully assessed in this study.
The findings of this study highlight the importance of maintaining healthy sleep patterns in reducing the risk of developing Alzheimer’s disease. By addressing circadian disruption and improving sleep quality, individuals may be able to lower their risk of dementia in later life. Additional research is needed to further elucidate the complex relationship between sleep and Alzheimer’s pathology.
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