Dementia can be looked at as an umbrella term which describes the range of symptoms a person can exhibit due to brain degeneration. These can include memory, judgment, attentiveness, speech, and other physical and mental abilities. Dementia can interfere with an individual's capacity to perform daily functions independently, anywhere from financing to driving to personal hygiene. There are dozens of causes of dementia, some which are reversible and others which are irreversible. Alzheimer's disease is a form of dementia which cannot be reversed, and happens to be the most common form of dementia in people 65 and older - it accounts for about 60% of all dementias. Alzheimer's disease causes damage to brain cells over time and can cause symptoms such as memory loss, changes in mood and personality, inability to perform daily activities, loss of initiative, hallucinations and delusions, etc. If an individual is diagnosed as having dementia, it is helpful to pursue further testing in order to pinpoint the type of dementia he or she has. This can help the person learn more about their options and pursue the best possible treatment available.