Sleep Clearance Declines with Age

A Nature Aging study using fMRI, modified MRI for CSF flow, and EEG found that the slow‑wave EEG pulses that drive cerebrospinal‑fluid flushing during sleep are on average much weaker in adults aged 60–84 than in younger adults, and that reduced neurovascular coupling partly—but not fully—explains the gap. Some older individuals retain youthful CSF pulses, suggesting heterogeneity in biological aging and modifiable risk factors. — If sleep‑driven brain clearance is impaired with age, it reframes dementia prevention, aging biomarkers, and public‑health priorities toward vascular, sleep, and lifestyle interventions that preserve nightly brain flushing.