What Is Mixed Dementia? What Are Its Symptoms?

Mixed dementia is a term used when a person has more than one type of dementia. Often, mixed dementia consists of Alzheimer's disease and vascular dementia, but it also refers to a combination of Alzheimer's and any other type of dementia.

The prevalence of mixed dementia is difficult to determine. Traditionally, clinicians have identified one primary type of dementia when determining a diagnosis for a patient, such as Alzheimer's disease or vascular dementia.

Researchers have increasingly discovered, however, that many people who have been diagnosed with one type of dementia may also have another kind. Autopsies, where the brain is examined after death, have often shown signs of Alzheimer's, vascular, and Lewy body dementia mixed together.

One study reported that 94% of its participants with dementia had been diagnosed with Alzheimer's. After death, autopsies of those people revealed that 54% of them showed evidence of another type of dementia in addition to Alzheimer's such as blood clots (vascular dementia) or Lewy bodies (Lewy body dementia).

According to the Alzheimer's Association, mixed dementia may be more likely to develop as people age since age is a risk factor for several types of dementia.

Mixed dementia is likely to present with symptoms similar to Alzheimer's disease. The symptoms of mixed dementia may progress faster or be manifested earlier because the brain is affected by more than one type of problem or damaged in more than one area.

A diagnosis of mixed dementia is made definitively after death when an autopsy is conducted. When the brain shows more than one type of abnormality such as a buildup of tau protein and blockages in the brain vessels, mixed dementia is diagnosed.

Some clinicians give a diagnosis of mixed dementia when a person displays symptoms of Alzheimer's but has had a cardiovascular health problem such as a stroke that would suggest that vascular dementia is also affecting the person. As imaging techniques improve and research continues to grow, it's likely that mixed dementia will be increasing diagnosed long before an autopsy is conducted.

While there are no medications specifically approved by the US Food and Drug Administration (FDA) to treat mixed dementia, it appears to respond favorably to some of the same medications that are approved to treat Alzheimer's disease. Research results have varied for participants with mixed dementia who were treated with cholinesterase inhibitor medications. Some results found that the cognitive decline that is expected in mixed dementia had slowed down, and others even demonstrated some limited improvement in memory and thinking.

Other treatment for mixed dementia- specifically the combination of Alzheimer's and vascular dementia- focuses on factors such as blood pressure treatment and cholesterol management, with the goal of reducing the likelihood of another stroke (and potentially the progression of vascular dementia).