
Dementia signs can appear years before diagnosis, from sleep and mood shifts to frailty
Noncognitive symptoms can appear years or even decades before dementia is diagnosed. Alzheimer’s typically progresses in three stages, with the first stage starting about 15–20 years before noticeable cognitive changes as amyloid beta plaques and tau tangles accumulate in the brain. Early signs include mood changes, sleep disturbances, and physical frailty, and lifestyle changes may prevent roughly 45% of dementia cases.











