Alzheimer's disease and other dementias.

All types of dementia involve mental decline that: • occurred from a higher level (for example, the person didn’t always have a poor memory) • is severe enough to interfere with usual activities and daily life • affects more than one of the following four core mental abilities • recent memory (the ability to learn and recall new information) • language (the ability to write or speak, or to understand written or spoken words) • visuospatial function (the ability to understand and use symbols, maps, etc., and the brain’s ability to translate visual signals into a correct impression of where objects are in space) • executive function (the ability to plan, reason, solve problems and focus on a task)