A tiny brain region controlling alertness could be the key to understanding the link between sleep and Alzheimer’s disease.
What your sleep can tell you about Alzheimer’s risk / © Credits
Changes in brain activity related to sleep may occur long before the symptoms of neurodegenerative diseases appear. Scientists have found a connection between the activity of a small brain region responsible for alertness and the rhythms of the rapid eye movement (REM) sleep phase, which is crucial for memory processes.
This was reported by Earth.com.
At the same time, scientists from the University of Liège emphasize that the results do not yet allow for the use of sleep characteristics to diagnose or predict Alzheimer’s disease.
The study focused on the locus coeruleus, a tiny cluster of nerve cells in the brainstem. This region releases norepinephrine and is involved in regulating alertness, attention, and transitions between sleep and wakefulness.
Scientists are particularly interested in the locus coeruleus because it is here that pathological changes in tau protein, characteristic of Alzheimer’s disease, may appear in the early stages.
What the sleep study revealed
The study involved 52 healthy individuals. 34 participants were between 18 and 31 years old, and another 18 were between 50 and 70 years old. Individuals with serious brain diseases, sleep disorders, or other conditions that could significantly affect the results were not included in the experiment.
After a week of regular sleep patterns, participants spent a night in the laboratory. Using electroencephalography, scientists monitored brain activity, paying special attention to theta rhythm during the REM phase and sigma activity just before its onset.
The activity of the locus coeruleus was assessed separately during the day using functional MRI while volunteers performed two different perception and reaction tasks.
Researchers found that in both age groups, a certain type of stronger daytime locus coeruleus response was associated with more pronounced theta activity during REM sleep. A similar connection was observed with sigma rhythm immediately before the start of this phase.
However, a different type of task yielded a different result: in older participants, a stronger response from this brain region was associated with less theta activity during REM sleep. No such clear link was recorded in younger volunteers.
Can sleep predict Alzheimer’s disease?
According to the authors of the study, the results may suggest that a certain balance of activity in the system regulating alertness is important for normal REM sleep. However, the study only established a correlation between the indicators and did not prove that changes in the locus coeruleus directly affect sleep or memory.
Furthermore, the scientists did not examine the volunteers’ tau protein levels, genetic predisposition to Alzheimer’s disease, memory impairment, or future risk of developing the disease.
Study author Gilles Vandewalle suggests that sleep may, in the future, become an accessible marker to help identify individuals with increased vulnerability even before obvious problems emerge. However, significantly larger and longer-term studies are needed for this.
Currently, the scientists’ conclusion is more cautious: the work of the small brain region controlling alertness is linked to certain REM sleep rhythms in healthy individuals. Whether these characteristics can be used for early detection of Alzheimer’s risk remains to be determined.
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