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Ask The Expert
December 26, 2013
The terms "Alzheimer's disease" and "dementia" are related, but they are not identical.
Dementia is a brain disorder. It includes:
- Memory loss
- Deficits in cognition (thinking, planning, and organizing abilities)
- A decline in emotional control or motivation
- Changes in social behavior
There are many types of dementia. Alzheimer's is by far the most common type. About a half of people with dementia are diagnosed with Alzheimer's.
People use these terms interchangeably. In part, that’s because it is very hard to tell types of dementia apart. Usually, the specific type of dementia can only be diagnosed by an autopsy after someone has died.
The diagnosis of Alzheimer's is based on finding specific abnormalities in and around nerve cells. These are called "beta-amyloid plaques" and "neurofibrillary tangles." They may be present in any aging brain. But in people with Alzheimer’s, there tend to be more of these defects.
Alzheimer’s disease affects areas of the brain involved in learning and memory. So, a common symptom is difficulty in recalling new information. Memory loss disrupts daily life. The person may get lost in a once-familiar neighborhood. He or she may also decline in the ability to make decisions, solve problems, or make good judgments. Mood and personality may change. A person might become more irritable, hostile, or disinterested.
The second most common type of dementia is "vascular dementia." Here, the loss of brain tissue results from a failing blood supply to the brain. Blood vessels are blocked, which deprives brain cells of oxygen. So, a person with this kind of dementia has multiple small strokes. Each event causes the death of a relatively small number of cells.
This process creates a "stepwise" pattern of decline. (In contrast, Alzheimer’s decline is gradual.) But the steps may be so small that the changes appear gradual.
Alzheimer's and vascular dementia are quite hard to tell apart. To confuse matters, they may even happen together in the same person.
Since the symptoms of different types of dementia look so similar, it is not surprising that people use these words interchangeably.
Unfortunately, once dementia has developed it is usually hard to reverse. But in a small number of cases, a doctor may be able to find a treatable cause for mental decline. For instance, dietary deficiencies, medications, infections, alcohol use and depression can all cause symptoms of dementia. And all of these illnesses can be treated.
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