Researchers developed a machine learning-based tool that estimates a person's "brain age" using sleep electroencephalography (EEG), a test that records electrical activity in the brain during sleep. Using AI, they calculated each person's Brain Age Index (BAI), which measures the difference between brain age estimated from sleep EEG patterns and chronological age. According to the study, "each 10-year increase in BAI was associated with a 39% higher risk of incident dementia," independent of many established dementia risk factors. "Our findings suggest that sleep EEG-based BAI may serve as a promising early digital marker for dementia risk stratification," the authors wrote. "Elevated sleep EEG-based BAI, a machine learning marker of brain aging, was independently associated with higher dementia risk in community-based populations," the authors concluded.