Mixed Dementia and 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.

Prevalence of Mixed 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.

Symptoms of Mixed 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.

Diagnosis

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, it's likely that mixed dementia will be increasingly diagnosed long before an autopsy is conducted.

Treatment of Mixed Dementia

While there are no medications specifically approved by the 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, particularly in those with mixed vascular-Alzheimer’s dementia.

Treatment for these patients may include cholinesterase inhibitors and glutamate regulators, both of which have been shown to lead to mild improvement in symptoms. Aducanumab is another medication approved by the FDA to treat Alzheimer's disease.

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