Alzheimer's disease is the most common type of dementia, affecting over half of all dementia sufferers.

Alzheimer's disease is caused by a loss of brain cells, probably related to an imbalance in the chemical messengers (neurotransmitters) in the brain.

AD begins slowly. At first, the only symptom may be mild forgetfulness. In this stage, people may have trouble remembering recent events, activities, or the names of familiar people or things. They may not be able to solve simple math problems. Such difficulties may be a bother, but usually they are not serious enough to cause alarm.

However, as the disease goes on, symptoms are more easily noticed and become serious enough to cause people with AD or their family members to seek medical help. For example, people in the middle stages of AD may forget how to do simple tasks, like brushing their teeth or combing their hair. They can no longer think clearly. They begin to have problems speaking, under-standing, reading, or writing. Later on, people with AD may become anxious or aggressive, or wander away from home. Eventually, patients need total care.

Alzheimer's disease tends to progress, deteriorate and lead to death within 7 to 10 years. However, the progress of the illness varies a lot between individuals. For some, the illness may progress slowly over many years, whereas for others it may progress rapidly.