Mixed dementia is a condition where an individual has more than one type of dementia simultaneously, with Alzheimer's disease and vascular dementia being the most common combination.
The word “dementia” is a general term that does not define a specific disease but simply the state of a person’s mental function. In fact, the condition in most cases entails a progressive decline in mental function and activity from a previously normal level, which with time, will become severe enough to interfere with the daily activities of the individual. An individual affected by dementia may manifest some specific deficits in areas that involve memory, language, mood, or behavior.
While the most frequent cause of dementia is Alzheimer's there are other conditions that can be responsible for it as well. Interestingly, there are also cases in which two, at times three, different types of dementia are present in the same patient, a condition known also as mixed dementia.
Having two conditions at the same time can make things even more complicated from a clinical point of view. In fact, this co-existence represents a dual impact on the brain structures and functions and often can result in a unique set of challenges for both the person affected, their caregivers and their doctors.
To better understand mixed dementia, we need to digress for a moment and consider the two conditions separately.
Alzheimer’s disease typically involves the build-up of amyloid plaques and tau tangles in particular brain regions, leading to memory loss, confusion, and progressive cognitive decline.
Vascular Dementia is the result of a significant reduction of blood flow and supply to the brain, most of the time due to strokes or other vascular problems. This lack of blood and nutrient to diffuse area of the brain can ultimately cause problems with reasoning, planning, judgment, and memory.
In a situation in which the two conditions are present in the same patient it is easy to observe what we call a combined and synergistic negative effect on the clinical manifestations. The symptoms of mixed dementia that a patient can experience can be more severe or even progress more rapidly than in either condition alone. At the same time, memory loss from Alzheimer's might be compounded and more severe by the cognitive difficulties due to the vascular dementia per se.
However, we should not forget that while Alzheimer’s and vascular dementia are the most common forms of mixed dementia, there are others as well. For instance, Alzheimer’s can also be seen in patients with Lewy bodies dementia. In very rare cases, there could be a situation in which three brain pathologic conditions co-exist: Alzheimer’s disease, vascular dementia and Lewy bodies dementia.
For broad information and resources related to Alzheimer’s disease, click here to visit Alzheimer’s Association website.
Domenico Praticò, MD, holds the position of the Scott Richards North Star Charitable Foundation Chair for Alzheimer’s Research and serves as a Professor and the Founding Director at the Alzheimer’s Center at Temple, as well as a Professor of Neural Sciences at Lewis Katz School of Medicine at Temple University.
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