It is common for a person with dementia to have a combination of two or more types of dementia. This is known as mixed dementia. For example, some people may have both Alzheimer’s disease and vascular dementia. In fact, some studies suggest that vascular dementia combined with another type of dementia is the most common type of dementia in older adults.
In a person with mixed dementia, it may not be clear exactly how many of a person's symptoms are due to Alzheimer's disease or another cause of dementia. Researchers are trying to better understand how the combined diseases may affect symptoms.