A meta-analysis showed that a brain age index derived from sleep EEG microstructures predicts the risk of dementia[1][2]. Researchers at UCSF and Beth Israel Deaconess Medical Center analyzed data from five cohorts of 7,105 participants aged 40 to 94, none with dementia at baseline[1][2]. Participants were followed for 3.5 to 17 years, during which approximately 1,000 developed dementia[1][2]. Every 10-year increase in brain age index increases the risk of dementia, even after accounting for factors such as education, smoking, BMI, physical activity, and genetic risk[1][2]. Important EEG patterns include delta waves in deep sleep, sleep spindles for memory storage, and sharp spikes (kurtosis) that reduce the risk of dementia[1][2]. These fine-structure patterns provide a better insight into brain aging than traditional sleep metrics, such as sleep duration or sleep efficiency[1][2].