Changes in slow sleep waves detected before Alzheimer’s symptoms — News-Medical

A study involving 116 adults in Barcelona, Spain, found that the shape of slow brain waves during deep sleep changes even in people without cognitive impairment but with abnormal amyloid biomarkers of Alzheimer’s disease. Such changes may be non-invasive markers of the preclinical stage of the disease, News-Medical reports , citing an article in the journal Alzheimer’s Research & Therapy.

How the study was conducted Participants spent one night each in the sleep laboratory at Hospital Clínic de Barcelona, where their sleep was assessed using polysomnography. The sample included 30 people without cognitive impairment and without abnormal amyloid biomarkers, 45 participants without cognitive impairment with such biomarkers, and 41 people with mild cognitive impairment or mild dementia associated with Alzheimer’s disease.

Scientists analyzed overall sleep structure, including wake time after sleep onset, sleep efficiency, and time to REM sleep. They separately examined slow-wave activity in the frontal regions of the brain: the number of waves, their steepness, amplitude, and duration. More current news is available on the UA.News Telegram channel Telegram .

The waves became flatter The most pronounced change was a gradual decrease in the steepness and amplitude of slow waves across the three study groups. The average wave slope declined from approximately 370 microvolts per second in the group without abnormal amyloid biomarkers to 342 in the group with such biomarkers and to 300 in patients with early Alzheimer’s disease.

Their duration increased at the same time. Participants with early-stage disease also stayed awake longer after falling asleep, had lower sleep efficiency, and took longer to reach REM sleep than both groups of people without cognitive impairment. In 76 such participants for whom follow-up data over approximately six and a half years were available, steeper waves and greater amplitude were associated with better cognitive function scores during that period.

Limitations of the findings The authors emphasized that the comparison between groups was cross-sectional and does not make it possible to determine whether sleep disturbances are a cause or consequence of disease development. Each participant’s sleep was recorded during only one night in the laboratory.

The researchers described conclusions about differences between men and women as preliminary because of the small sizes of the respective groups.