| Response from David B. Reuben, MD
Professor and Archstone Foundation Endowed Chair, Department of Medicine, University of California, Los Angeles; Chief, Division of Geriatrics, UCLA Medical Center, Santa Monica, California
Making a diagnosis of vascular dementia is complicated for several reasons. First, vascular dementia has multiple causes and clinical types. Second, in contrast to Alzheimer disease, the diagnosis of vascular dementia has no pathognomonic criteria. Third, the clinical diagnostic criteria are poorly validated. Fourth, on MRI, white-matter lesions, which are related to cerebral hypoperfusion or ischemia, are nonspecific findings yet often are interpreted as diagnostic. Fifth, many patients with vascular dementia also have other causes of dementia (eg, Alzheimer disease)—so-called "mixed dementia."
Several causes and presentations of vascular dementia have clinical value. Perhaps the most obvious patients are those who meet criteria for dementia and have sustained a clinical stroke—either large artery (usually cortical) or small artery (lacunes) in subcortical areas. Strokes are usually confirmed by neuroimaging (MRI is more sensitive than CT) that demonstrates either multiple infarcts or a single strategically placed infarct (eg, angular gyrus, thalamus, brain forebrain, posterior cerebral artery, or anterior cerebral artery).
Patients with dementia who have evidence of cerebral infarction on MRI without clinical presentations of stroke may also have vascular dementia. Finally, chronic subcortical ischemia of small vessels in the periventricular white matter can result in the loss of neurons and supporting brain cells, leading to vascular dementia.
As result of these diverse causes, the clinical presentation of vascular dementia varies considerably. Features that indicate cortical dysfunction (often caused by cerebral embolism) include executive dysfunction; aphasia, apraxia, and agnosia; hemineglect visual-spatial and construction difficulty; and anterograde amnesia. Features that indicate subcortical dysfunction (typically owing to lacunar infarcts and chronic ischemia) include focal motor signs, gait disturbance and falls, urinary tract symptoms, pseudobulbar palsy, personality changes, psychomotor retardation, and abnormal executive function. Clinically, executive dysfunction may be the earliest presenting symptom, even when cognitive impairment is mild.
The temporal relationship between stroke and the onset of cognitive impairment is important in establishing the diagnosis of vascular dementia. For example, dementia occurring within 3 months of a recognized stroke or a pattern of stepwise progression of cognitive deficits strongly supports the diagnosis.
A clinically useful tool for distinguishing vascular dementia from Alzheimer disease is the Hachinski Ischemic Score, which assigns two points to each of the following:
History of stroke;
Focal neurologic symptoms; and
Focal neurologic signs
and one point to the following:
Preservation of personality;
A score of 7 or higher suggests vascular dementia, whereas a score of 4 or less suggests Alzheimer disease.
Developed in association with the UCLA Alzheimer's and Dementia Care Program.
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Cite this: David B. Reuben. What Is Vascular Dementia? - Medscape - Jul 15, 2015.