Dementia is a decline in cognitive function. To be considered dementia, mental impairment must affect at least two brain functions. Dementia may affect:
Dementia is not a disease. It may be caused by a variety of illnesses or injuries. Mental impairment may range from mild to severe. It may also cause personality changes.
Some dementias are progressive. This means they get worse over time. Some dementias are treatable or even reversible. Some experts restrict the term dementia to irreversible mental deterioration.