The definitive diagnosis of mixed dementias can be made only by an extensive neuropathological examination. These diseases are mainly observed in elderly patients and further increase during the aging process even when they started as a single illness. They are for 85% of patients due to a combination of Alzheimer, Lewy body, and vascular pathology. The last can be due to cerebral amyloid angiopathy or arteriosclerotic cerebrovascular disease. However, some neurodegenerative diseases remain mainly unmixed, such as frontotemporal lobar degeneration, amyotrophic lateral sclerosis, progressive supranuclear palsy, and corticobasal degeneration. This can mainly be explained by the favorable vascular profile of the patients with these diseases. The clinical diagnosis of most mixed neurodegenerative and cerebrovascular dementia diseases can be suspected by means of magnetic resonance imaging and positron emission tomography of the brain, using glucose, amyloid, and tau tracers.
Elsevier, Diagnosis and Management in Dementia, Volume 1, August 2020, Pages 3-15