Mild cognitive impairment (MCI)

Defined by Petersen's diagnostic criteria (objective cognitive decline on testing, preserved daily functioning, not meeting dementia threshold), mild cognitive impairment exceeds normal aging without impairing independence. Roughly 10 to 15 percent of people with MCI progress to dementia each year in clinic-based cohorts, with lower rates in community samples. In longevity medicine it is a critical intervention window: lifestyle changes, treatment of vascular risk, sleep optimisation, and hearing correction can stabilise or partially reverse symptoms.