What are stages of dementia?

The stages of dementia describe how the illness progresses, most often as early, middle and late, or on a seven point scale from no impairment to very severe decline. In the early stage a person is largely independent but forgetful. The middle stage, usually the longest, brings more need for help with daily tasks. The late stage requires full-time care.

There is no single count. The Alzheimer's Association describes three broad stages: early, middle and late, also called mild, moderate and severe. Clinicians sometimes use a seven stage scale that runs from no impairment to very severe decline. Both describe the same progression in more or less detail, and people move through the stages at very different rates.

Wandering is most common in the middle stage of dementia, when the Alzheimer's Association lists the risk of wandering and becoming lost among typical changes. It can happen at any stage, though. The association says six in 10 people living with dementia will wander at least once, and anyone who has memory problems and is able to walk is at risk.

Sundowning is not tied to a single stage, but it is most often noticed in the middle stage, when the Alzheimer's Association lists changes in sleep patterns such as becoming restless at night. Sundowning describes anxiety, agitation, pacing and disorientation that begin around dusk. The association says it may occur because of disease progression and changes in the brain.

There is no fixed timeline. The Alzheimer's Association says a person with Alzheimer's lives on average four to eight years after diagnosis, but can live as long as 20 years. The middle stage is typically the longest and can last for many years. Stages are a guide, not a timetable, and people move through them at very different rates.