Sleeping brain reveals dementia risk decades early

Researchers analysed EEG recordings from around 7,000 adults. An EEG (electroencephalogram) measures the brain’s electrical activity via scalp electrodes during sleep. The algorithm calculated a ‘brain age’ for each participant based on those sleep patterns.

The finding was striking. People whose estimated brain age exceeded their actual age showed a markedly higher dementia risk. According to the researchers, every additional ten years of brain ageing raised dementia risk by nearly 40 percent. That is a substantial figure, though the study shows an association, not a proven cause.

Why sleep is such a useful measuring stick

During sleep, the brain carries out maintenance. Waste proteins are cleared via the glymphatic system, a network of channels surrounding blood vessels that works most efficiently during deep sleep. As the brain ages, the pattern of sleep oscillations changes. That change is detectable even before a person notices any symptoms.

The concept of a ‘brain age clock’ is not new, but previous approaches were expensive and complex. EEG recordings collected during routine sleep studies are relatively accessible. If analyses like this prove reliable at scale, early identification of dementia risk could, in principle, become more widely available.

What this does not yet prove

The study is observational: people with an older brain age more often developed dementia, but that does not mean a younger brain age prevents it. It also remains unclear which factors most strongly drive brain age. Sleep quality, genetics, lifestyle and existing illness all play a role.

From a longevity perspective the finding is nonetheless noteworthy. Sleep is one of the few lifestyle factors people can actively influence. If sleep patterns are indeed an early signal of accelerated brain ageing, that adds further reason to treat sleep as a serious component of prevention.

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