Unit
- Vascular dementia pathophysiology: Vascular dementia results from reduced blood flow to the brain, often due to strokes, small vessel disease, or chronic hypoperfusion. The most common subtypes include multi-infarct dementia (multiple cortical infarcts), subcortical ischemic vascular dementia (Binswanger disease), and strategic single-infarct dementia. Each subtype presents with distinct cognitive and functional impairments that influence care planning.
- Cerebral small vessel disease: This is the leading cause of subcortical vascular dementia, involving damage to arterioles, capillaries, and venules. Hypertensive arteriopathy and cerebral amyloid angiopathy are frequent pathologies. The resulting white matter lesions, lacunar infarcts, and microbleeds impair executive function, processing speed, and gait.
- Cortical vs. subcortical involvement: Cortical infarcts cause focal deficits such as aphasia or neglect, while subcortical damage affects frontal-subcortical circuits, leading to apathy, depression, and executive dysfunction. Mixed pathology (e.g., vascular and Alzheimer disease) is common in older adults, complicating diagnosis and treatment.
- Risk factors for vascular dementia: Hypertension, diabetes, hyperlipidemia, smoking, atrial fibrillation, and atherosclerosis are modifiable risk factors. Age, genetics (e.g.,
APOE e4), and prior stroke history increase susceptibility. Managing these factors reduces incidence and slows progression. - Neuropathological changes: Gross examination often shows cortical atrophy, ventricular enlargement, and multiple infarcts. Microscopically, gliosis, demyelination, and loss of neurons are evident around ischemic areas. Amyloid plaques and tau tangles are absent unless mixed pathology exists.
- Impact on cerebral blood flow: Chronic hypoperfusion leads to energy failure, oxidative stress, and inflammation. The blood-brain barrier becomes disrupted, allowing harmful substances into brain tissue. These processes progressively damage neurons and white matter tracts.
- Clinical heterogeneity: Symptoms vary widely depending on the location and extent of vascular damage. Common signs include stepwise cognitive decline, focal neurological signs, early gait impairment, mood changes, and urinary urgency. This variability demands individualized assessment and care plans.
- Relationship to stroke: Up to one-third of stroke survivors develop dementia within one year. Strategic infarcts in the thalamus, angular gyrus, or left hemisphere are particularly high risk. Secondary prevention through antiplatelet therapy, blood pressure control, and statins is essential.
- Diagnostic imaging approaches: MRI is preferred for detecting white matter hyperintensities, lacunar infarcts, and microbleeds. CT is useful for acute hemorrhage or large infarcts. Advanced techniques like diffusion tensor imaging and arterial spin labeling can assess white matter integrity and cerebral perfusion, aiding early diagnosis and monitoring progression.
- Cognitive domains affected: Executive function is most commonly impaired due to disruption of frontal-subcortical circuits. Attention, processing speed, and verbal fluency also decline, while episodic memory may be relatively preserved early on. Visuospatial deficits and apraxia can occur with parietal or occipital involvement.
- Preventive and therapeutic strategies: Strict blood pressure control (target less than 130/80 mmHg) and management of diabetes and hyperlipidemia are primary preventive measures. Antithrombotic therapy for atrial fibrillation and antiplatelet agents after stroke reduce recurrence. Lifestyle modifications including exercise, diet, and smoking cessation also lower risk.
Terminology
- Vascular dementia
- Dementia caused by reduced cerebral blood flow, leading to cognitive decline.
- Small vessel disease
- Microvascular pathology affecting cerebral arterioles, common in aging and hypertension.
- Multi-infarct dementia
- Dementia due to multiple cortical strokes accumulating over time.
- Subcortical ischemic vascular dementia
- Dementia from white matter lesions and lacunes, often related to Binswanger disease.
- Mixed dementia
- Coexistence of vascular and Alzheimer disease pathology.
Quick Revision
- Vascular dementia is driven by ischemic damage from strokes, small vessel disease, or hypoperfusion.
- Subtypes include multi-infarct, subcortical ischemic, and strategic single-infarct dementia.
- Risk factors are largely modifiable: hypertension, diabetes, smoking, and atrial fibrillation.
- Symptoms vary based on infarct location but often include stepwise decline and focal deficits.
- Mixed pathology with Alzheimer disease is common and complicates diagnosis.