Some memory loss is normal as we age. Besides a gradual memory loss, there is a decline in the ability to perform routine tasks. A person begins to forget basic information about themselves and their family members. They can't remember things they used to do every day or protect themselves from common dangers. They become disoriented to time and place, and their judgement is impaired.
Personality changes are common, and there is a loss of language and communication skills.
Finally, people with Alzheimer's disease gradually forget how to perform basic activities, such as how to eat, dress and toilet themselves. It's no longer true that AD is a diagnosis of exclusion. Now a physician can use medical tests and brain imaging to identify and document specific changes in the brain. AD is caused by the deterioration of nerve cells in the brain. While we don't know why nerve cells die with AD, we do know the chances of getting AD increase with age.