"Autopsy studies looking at the brains of people who had Dementia suggest that a majority of those age 80 and older probably had 'Mixed Dementia,' caused by processes related to both Alzheimer’s disease [or, other Dementia] and vascular disease. In fact, some studies indicate that mixed vascular-degenerative Dementia is the most common cause of dementia in the elderly.
In a person with mixed Dementia, it may not be clear exactly how many of a person’s symptoms are due to Alzheimer’s or another type of Dementia. In one study, about 40 percent of people who were thought to have Alzheimer’s were found after autopsy to also have some form of cerebrovascular disease. Several studies have found that many of the major risk factors for vascular disease also may be risk factors for Alzheimer’s disease.
Researchers are still working to understand how underlying disease processes in Mixed Dementia influence each other. It is not clear, for example, if symptoms are likely to be worse when a person has brain changes reflecting multiple types of Dementia. Nor do we know if a person with multiple Dementias can benefit from treating one type, for example, when a person with Alzheimer’s disease controls high blood pressure and other vascular disease risk factors."
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