About Alzheimer's & Dementia
What is Mixed Dementia?
Mixed dementia is a condition where changes representing more than one type of dementia occur simultaneously in the brain. In the most common form, the plaques and tangles associated with nerve cells in Alzheimer's disease are present along with blood vessel changes associated with vascular dementia. The plaques and tangles of Alzheimer’s disease can often coexist with Lewy bodies, the abnormal protein deposits found in dementia with Lewy bodies and Parkinson’s disease dementia. In some cases, a person may have changes linked to all three -Alzheimer’s disease, vascular dementia and dementia with Lewy bodies.
What are the symptoms?
Mixed dementia symptoms may vary, depending on the types of brain changes involved and the areas of the brain affected. In many cases, symptoms may be similar to (or even indistinguishable from) those of Alzheimer’s disease or another specific type of dementia. In othercases, a person’s symptoms may clearly indicate the existence of more than one type of dementia.
How common is Mixed Dementia?
Researchers don’t know exactly how many older adults living with a specific type of dementia are actually living with mixed dementia, but autopsy studies indicate that the condition may be significantly more common than previously believed. Autopsy studies play a key role in diagnosing mixed dementia because scientists are not yet able to measure most dementia-related brain changes in living individuals. Data collected from the first 141 volunteers from the Rush memory and aging Project Study conducted in Chicago, show that more than 50 percent of those whose brains had the microscopic changes of Alzheimer’s had pathologic evidence of one or more coexisting dementias.
Although mixed dementia is not a common diagnosis, many researchers believe it deserves more attention. This is because the combination of two or more types of dementia-related brain changes may have a greater impact on the brain than a single type. Evidence suggests that the presence of more than one type of dementia-related change may increase the chances a person will develop symptoms. In fact, having symptoms of more than one type of dementia increases the odds of being diagnosed by more than 3 times.
How is it diagnosed?
Most autopsy results that show the presence of mixed dementia occurred in people who were originally diagnosed with one specific type of dementia during their life, most commonly Alzheimer’s disease. For example, in a study involving long-term cognitive assessments followed by eventual brain autopsy, 94% of participants who were diagnosed with dementia were diagnosed with Alzheimer’s disease...yet the autopsy results showed that 54% had coexisting pathology. The most common coexisting condition was previously undetected blood clots or other evidence of Vascular dementia. Lewy bodies were the second most common coexisting condition.
What kind of treatment is available?
Because most people living with mixed dementia are diagnosed with just a single type of dementia, a physician might base the pharmaceutical decisions / prescriptions on the type of dementia that has been diagnosed.
Currently, there aren’t any pharmaceutical drugs available specifically targeted to treating mixed dementia. In situations where the physician considers Alzheimer’s disease to be among the conditions contributing to a person’s dementia symptoms, they may prescribe the medications intended for Alzheimer’s disease treatment.
Many researchers believe that by increasing our understanding of mixed dementia, coupled with recognizing that vascular changes are the most common coexisting brain change, we may create an opportunity to reduce the number of people who develop dementia. Controlling our risk factors for diseases of the heart and blood vessels (like blood pressure, cholesterol levels, body weight and diabetes) may also protect the brain from vascular changes.