Small interruptions during sleep may offer clues about Alzheimer’s disease years before memory problems begin, according to research from the University of Liège in Belgium.
Scientists studied sleep in more than 500 healthy people and compared their sleep patterns with genetic factors linked to Alzheimer’s disease. The findings were published in the journal Sleep.
Alzheimer’s disease develops slowly and can begin changing the brain many years before a person is diagnosed. It is the most common cause of dementia, gradually affecting memory, thinking and the ability to manage everyday life. Researchers are therefore searching for early signs that might reveal increased vulnerability while people are still healthy.
Sleep has become an important area of this research. Poor sleep is common as people age, and previous studies have linked sleep problems with changes in brain health. Scientists are trying to understand whether disturbed sleep contributes to Alzheimer’s disease, results from very early brain changes, or both.
The University of Liège team examined more than 500 people who showed no signs of Alzheimer’s disease. Most were young adults between 18 and 31, while another group was between 50 and 69. Researchers calculated each person’s polygenic risk score, which combines information from many genetic differences associated with Alzheimer’s.
A polygenic score does not tell someone whether they will develop Alzheimer’s disease. Genes are only one part of risk, alongside age, health, lifestyle and other factors. Instead, the score gives researchers a way to compare people who have somewhat higher or lower inherited susceptibility.
The scientists then compared these scores with detailed measurements of sleep. One feature stood out among the middle-aged and older participants: people with higher genetic risk tended to experience more micro-awakenings during the night. The same relationship was not seen in the younger adults.
Micro-awakenings are very short periods in which brain activity shifts toward wakefulness. A person may not become fully conscious and may have no memory of waking the next morning. However, frequent interruptions can break up the normal structure of sleep and reduce the amount of uninterrupted restorative sleep.
The finding suggests that changes in sleep may become connected with Alzheimer’s vulnerability during midlife, before clear memory or thinking problems develop. Researcher Puneet Talwar said certain patterns of micro-awakenings could potentially be linked with conditions that favor the buildup of proteins involved in Alzheimer’s disease. This remains a possible explanation rather than proof of cause.
The researchers are also interested in a tiny brain region called the locus coeruleus. Located deep in the brainstem, it helps control alertness, attention and the movement between sleeping and waking. Despite its small size, it may be important in understanding some of the earliest biological changes associated with Alzheimer’s.
The locus coeruleus has attracted attention because abnormal deposits of a protein called tau can appear there early in life. Tau normally helps support nerve cells, but in Alzheimer’s disease abnormal forms can collect inside the brain. Scientists still do not fully understand what very early changes in this brain region mean for a person’s future risk.
Earlier work by the Liège researchers used an unusually powerful 7-Tesla MRI scanner to study the locus coeruleus in detail. That research linked features of this brain region with sleep quality, including how quickly people fell asleep and how deeply they slept. The team also found connections with REM sleep, a stage involved in memory and emotional processing.
Together, the studies raise the possibility that sleep measurements could one day become part of early Alzheimer’s risk assessment. Sleep can be measured without waiting for memory problems to appear, and some forms of monitoring are relatively easy compared with expensive brain scans. Researchers are also interested in whether improving sleep could eventually help protect vulnerable people.
However, the current study cannot show that micro-awakenings cause Alzheimer’s disease. It found an association between more frequent sleep interruptions and greater genetic risk in one age group, not evidence that people with disrupted sleep will develop dementia.
Many common conditions can disturb sleep, and most people who wake briefly during the night should not interpret this as a sign that they have Alzheimer’s.
The study’s inclusion of healthy people across different ages is valuable because it allows scientists to look for changes before disease symptoms emerge. Its genetic approach also offers a way to study vulnerability without waiting decades to see who develops Alzheimer’s.
Still, larger and longer studies are needed to confirm the pattern and determine whether sleep changes can actually predict future disease.
The research is therefore best viewed as an early clue rather than a new Alzheimer’s test. If future studies repeatedly find the same relationship and show that sleep changes appear before other signs of disease, nighttime sleep could become one piece of a broader risk assessment.
For now, the findings strengthen the idea that sleep and brain health are closely connected long before old age.
If you care about Alzheimer’s disease, please read studies about the protective power of dietary antioxidants against Alzheimer’s, and eating habits linked to higher Alzheimer’s risk.
For more health information, please see recent studies that oral cannabis extract may help reduce Alzheimer’s symptoms, and Vitamin E may help prevent Parkinson’s disease.
Source: University of Liège.
