Vascular dementia is cognitive impairment resulting from cerebrovascular disease — strokes (large or small), white matter ischemia, or both. Vascular contribution to dementia is more common than pure vascular dementia — "mixed dementia" with both Alzheimer's and vascular pathology is the rule rather than the exception in older patients.
Stepwise vs gradual decline: classic vascular dementia shows stepwise cognitive decline — sudden decrements followed by plateaus, corresponding to clinical or subclinical strokes. In practice, many patients have mixed gradual decline from white matter ischemia plus occasional stepwise drops from larger events. The pattern hints at vascular contribution without being pathognomonic.
Imaging characteristics: MRI typically shows multiple infarcts (large-vessel cortical or subcortical), white matter hyperintensities (small-vessel ischemic changes), and sometimes microbleeds (amyloid angiopathy contribution). The volume and location of damage correlate with cognitive impairment. Strategic infarcts in thalamus, hippocampus, or basal ganglia can cause major impairment from small lesions.
Subtypes of vascular cognitive impairment:
Multi-infarct dementia — multiple cortical or large subcortical strokes accumulating to produce dementia.
Subcortical vascular dementia — small-vessel disease with extensive white matter changes and small lacunar infarcts. Often manifests as executive dysfunction, processing speed slowing, and emotional lability without prominent memory loss.
Strategic infarct dementia — single critical lesion (thalamus, hippocampus) producing substantial impairment.
Hypoperfusion dementia — diffuse hypoperfusion from cardiac or systemic causes.
Clinical features that suggest vascular contribution: stepwise decline, focal neurologic signs (corticospinal weakness, sensory loss, dysarthria, ataxia), early gait disturbance disproportionate to memory loss, prominent executive dysfunction with relatively preserved memory, emotional lability, history of cerebrovascular events, vascular risk factors.
Vascular dementia is the most preventable dementia. Aggressive management of cardiovascular risk factors — hypertension, diabetes, hyperlipidemia, smoking cessation, atrial fibrillation, sleep apnea — reduces the risk of further infarcts and slows progression even after diagnosis. This is the dementia where ongoing primary care intervention substantially affects trajectory.
Treatment: cholinesterase inhibitors have modest benefit, similar to or smaller than in AD. Addressing comorbid AD pathology if present. Antiplatelet therapy if appropriate. Statin therapy. Blood pressure control with attention to avoid hypotension that worsens hypoperfusion. Treatment of comorbid depression (common after stroke) substantially improves outcomes.
When you encounter a patient with cognitive impairment plus vascular risk factors or imaging evidence of cerebrovascular disease, vascular contribution is likely. The intervention is real and effective — aggressive risk factor management changes trajectory. Even after dementia diagnosis, ongoing prevention matters.