How old is your brain, exactly? Brain age may impact dementia risk

• Studies looking at the association between sleep patterns and future dementia risk have shown mixed results.
• A recent study used brain wave patterns recorded by an electroencephalogram (EEG) during a sleep study to estimate the brain age of over 7,000 participants.
• The study found that having a brain age older than actual chronological age by 10 years was associated with an 39% higher future risk of dementia.
• These findings suggest that brain age, assessed based on sleep-EEG patterns, could be potentially used to screen individuals for dementia in the future.

A recent study published in JAMA Network Open used a machine learning model to estimate brain age from complex sleep brain wave patterns obtained from over 7,000 participants.

It found that more rapid brain aging relative to actual chronological age was associated with an increased risk of dementia.

Previous studies investigating the association between broader sleep patterns, like sleep quantity and sleep quality, have yielded inconsistent results.

In contrast, the present study assessed the granular differences in sleep wave patterns that are more closely linked to brain function and dementia risk.

Study co-author Yue Leng, PhD, an associate professor of psychiatry at the University of California, San Francisco, told Medical News Today that:

“This study shows that sleep is not just restorative—it also provides a powerful window into brain health. By analyzing brain activity during sleep, we can estimate a person’s ‘brain age,’ which may reveal whether the brain is aging faster or slower than expected.”

“This study goes beyond conventional sleep measures like sleep stages or sleep efficiency, which have often shown weak or inconsistent links with dementia risk. Instead, it uses richer EEG [electroencephalogram] microstructure to generate a single, interpretable marker,” added another co-author, Matthew Pase, PhD, a professor at Monash University in Melbourne, Australia.

Christopher Allen, MD, a sleep specialist who was not involved in this research, told MNT that “this study supports the idea that sleep is not just a symptom of brain health decline but may also be a measurable early marker of neurodegenerative risk.“

“At the same time,“ Allen cautioned, “it is not ready to be interpreted as a standalone diagnostic tool. The next step is validation in more practical settings and determining how this type of sleep biomarker might complement other dementia risk markers in real-world care.”