“Dementia” is the word used to describe loss of memory, logical thought, and social abilities to the point that it interferes with daily life.
Dementia is not a normal part of aging. (Many people in their nineties function very well.) But dementia does become more common with age. Consider:
- 3 percent of adults age seventy to seventy-four have some form of dementia
- 33 percent of those age ninety and older
Dementia is not a disease in and of itself. It is merely a collection of symptoms.
There are many, many causes of dementia. Alzheimer’s disease is the most common cause (about 80 percent). There is also vascular dementia, caused by not enough blood to the brain. People who have had a stroke or brain bleed may develop vascular dementia. Dementia can also result from a long history of heavy alcohol use, a tumor, or a brain disease such as Huntington’s disease. So far, these types of conditions are not curable.
Temporary dementia can occur because of depression, dehydration, medication side effects, or a fever or infection. A vitamin deficiency or a thyroid disorder can also result in dementia symptoms. These temporary conditions mean that the dementia may be curable if the underlying cause is treated.
If dementia is a concern for your family member, it is important to have your relative tested to identify which condition is at the root of the memory problem. If it can be cured, you want to do so right away. Even for conditions that can’t be cured, medications can slow the progression of the disease. But they must be started in the early stages.


