Could subtle changes during sleep reveal vulnerability to Alzheimer's disease years before memory problems become noticeable? Researchers at ULiège, supported by the Stop Alzheimer's Foundation, are investigating whether the sleeping brain may contain early clues. Scientists from the University of Liège (GIGA Neurosciences) examined sleep patterns in more than 500 healthy people.
Among participants in middle age, more frequent nighttime micro awakenings were associated with a higher genetic risk of developing Alzheimer's disease. That relationship was not detected among younger adults. The findings, published in the journal Sleep, raise the possibility that sleep measurements could eventually help researchers identify people who may be more vulnerable to Alzheimer's before symptoms develop.
Looking for Alzheimer's Clues Before Symptoms Researchers have spent years investigating connections between disturbed sleep and neurodegenerative diseases. The University of Liège study adds another piece to that research by suggesting that the relationship between sleep and Alzheimer's risk may begin well before recognizable symptoms emerge. Because genetics play a partial role in Alzheimer's disease (Alzheimer's disease is neither purely hereditary nor entirely independent of genes), the researchers calculated a polygenic risk (i.e., summarizing the combined influence of your genes on your probability of developing a given disease in a single figure) for more than 500 healthy participants.
Most were young adults (aged 18 to 31), while the study also included an older group (aged 50 to 69). Importantly, the polygenic risk measured in the study remained low and cannot determine whether any particular person will eventually develop Alzheimer's disease. The researchers then compared these genetic risk estimates with different characteristics of each participant's sleep.
The analysis revealed an association between genetic risk for Alzheimer's disease and the frequency of nighttime micro awakenings. These are very brief bursts of brain activity that can interrupt the normal sleep cycle without causing someone to become fully awake. Among the younger participants, researchers found no connection between these micro awakenings and Alzheimer's genetic risk.
A different pattern appeared in the older group. Participants who experienced more frequent micro awakenings also tended to have higher genetic risk, despite being healthy, relatively young and free of Alzheimer's symptoms. "These micro-awakenings are therefore not insignificant," emphasizes Puneet Talwar, a researcher at the GIGA ULiège laboratory, "certain profiles could promote the accumulation of proteins involved in Alzheimer's disease and be associated with increased vulnerability." The researchers also examined the locus coeruleus, a tiny area deep within the brainstem that is roughly the size of a grain of rice.
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