Researchers establish a link between sleep disorders and cognitive decline: an important discovery for medicine ?

Même au milieu de la vie, un sommeil perturbé pourrait être lié à des troubles de la mémoire et de la pensée quelques années plus tard. Maridav/Shutterstock

The quality of your sleep could be a reliable indicator for predicting possible cognitive disorders. In any case, this is what an American study reveals, which suggests an association between certain sleep disorders at age 30 or 40 and cognitive decline a decade later. A discovery which could ultimately make it possible to detect certain neurodegenerative diseases, including Alzheimer's disease, at an early stage, or even improve their prevention.

People who have disrupted sleep at the ages of 30 and 40 are more likely to develop memory problems and see their cognitive performance decline ten years later. These are the findings of a study published online in Neurology, the medical journal of the American Academy of Neurology. Be careful, however, it is not the quantity of sleep that is linked to cognitive decline, but the quality of it, as clarified by the researchers behind this work.

"Because signs of Alzheimer's disease begin to accumulate in the brain decades before symptoms appear, it is It is essential to understand the link between sleep and cognition at an early stage of life to understand the role of sleep disorders as a risk factor for the disease. Our results indicate that it is the quality rather than the quantity of sleep that matters most for cognitive health in middle age, explains Yue Leng, an epidemiologist at the University of California, San Francisco, in a press release.

This work is based on the analysis of the duration and quality of sleep of 526 people aged on average 40 years, followed for eleven years. Asked to wear a wrist activity monitor for three consecutive days on two occasions, one year apart, participants were also asked to provide information on the times they went to bed and lifted, answer a questionnaire on the quality of their sleep, and carry out a series of memory and thinking tests. Among the main lessons of this research, the scientists indicate that 46% of participants reported having slept poorly, and that all of the people monitored presented sleep fragmentation – which is based on short and repeated interruptions of sleep. – of the order of 19%.

A risk multiplied by two

After dividing the participants into three groups based on their personal sleep fragmentation score, the researchers observed that 44 of the 175 people with the most disrupted sleep had “poor cognitive performance”, compared to only 10 of the 176 people whose sleep was the least disturbed. "After adjusting for age, gender, ethnicity and education, those whose sleep was most disrupted had more than twice as much sleep more risk of having poor cognitive performance than those whose sleep was the least disturbed, specifies the study.

The study has numerous limitations, starting with the sample size which remains small. The researchers also point out that “the study does not prove that sleep quality causes cognitive decline,” but “only shows an association.” . They now hope to be able to conduct more in-depth research, with a larger sample, in order to highlight a potential association between sleep disorders and cognition at various stages of life. "Future studies could open up new perspectives for the prevention of Alzheimer's disease later in life,” concludes Yue Leng.