Vascular Dementia

• Large-vessel atherosclerotic disease and strategic infarcts: Atherosclerotic plaques in major cerebral vessels (internal carotid, middle cerebral, anterior cerebral arteries) cause hemodynamically significant stenosis or acute thromboembolism, resulting in territorial infarcts affecting critical cognitive networks. Strategic lacunar infarcts in the thalamus, internal capsule, or basal ganglia—despite small volume—produce disproportionate cognitive impairment by disconnecting frontal executive networks from deeper processing centers. This explains why VaD patients often present with subcortical dementia features (slowed processing, executive dysfunction) rather than cortical features.

• Small-vessel disease and white matter injury: Chronic hypoperfusion from small penetrating arteries (particularly those supplying deep white matter) leads to leukoaraiosis (white matter hyperintensities on MRI). The pathophysiology involves lipohyalinosis and microatheroma formation in arterioles, resulting in progressive demyelination, axonal loss, and disrupted connectivity between cortical and subcortical structures. This reduces cerebral blood flow below critical thresholds (~30-40 mL/100g/min) needed for normal cognitive function, particularly in watershed zones. The cumulative burden of small-vessel disease correlates more strongly with cognitive decline than large infarct volume in many VaD patients.

• Chronic hypoperfusion and metabolic failure: Beyond acute infarction, sustained reduced cerebral perfusion pressure triggers mitochondrial dysfunction, impaired glucose metabolism, and excitotoxicity. Chronically ischemic tissue exhibits reduced ATP production, leading to failure of Na+/K+-ATPase pumps and subsequent calcium influx with activation of proteases and apoptotic cascades. This chronic metabolic failure explains why cognitive decline may progress even in the absence of clinically apparent new strokes, representing a key distinction from models predicting stepwise decline only after recognized infarction.

• Blood-brain barrier disruption and neuroinflammation: Endothelial dysfunction and loss of tight junction integrity increase blood-brain barrier permeability, allowing immune infiltration and microglial activation. Persistent neuroinflammation releases cytotoxic mediators (TNF-α, IL-1β, IL-6) that amplify neuronal injury beyond the initial ischemic zone. Perivascular accumulation of inflammatory cells perpetuates white matter damage through demyelination and axonal degeneration.

• Amyloid angiopathy and cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL): Amyloid-β deposition in vessel walls causes congophilic amyloid angiopathy (CAA), compromising vascular integrity independent of atherosclerotic mechanisms. In CADASIL (NOTCH3 mutations), abnormal arterial smooth muscle degeneration causes progressive arteriopathy with recurrent subcortical infarcts and extensive white matter disease, representing a genetic form of VaD with earlier onset (30-50 years).

Vascular risk factors driving large-vessel disease

• Hypertension (most modifiable risk factor; present in ~60-80% of VaD patients)—chronic elevation causes arterial stiffening, endothelial dysfunction, and accelerated atherosclerosis
• Atrial fibrillation (cardioembolic source producing territorial infarcts; increases dementia risk 2-4 fold)
• Diabetes mellitus (accelerates atherosclerosis and causes microvascular dysfunction)
• Dyslipidemia (low HDL and elevated triglycerides particularly associated with small-vessel disease)
• Cigarette smoking (dose-dependent relationship with vascular cognitive impairment)
• Hyperhomocysteinemia (independent risk factor for both large- and small-vessel disease)

Small-vessel disease-specific causes

• Chronic hypertension (primary driver of lipohyalinosis in penetrating arterioles)
• Diabetes with poor glycemic control (microvascular dysfunction)
• Cerebral amyloid angiopathy (hereditary: Dutch-type NOTCH3 mutations; sporadic: associated with Alzheimer pathology)
• CADASIL (NOTCH3 mutations; autosomal dominant inheritance; presents with migraines, recurrent strokes, and progressive dementia in fourth-fifth decades)
• Cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL) (HTRA1 mutations; more aggressive small-vessel disease)
• Leukoaraiosis from chronic hypoperfusion (graded as 0-3 on Fazekas scale; presence independently predicts cognitive decline)

Cardiac sources producing infarction

• Endocarditis with septic emboli
• Cardiac thrombus (post-MI, dilated cardiomyopathy)
• Prosthetic valves with inadequate anticoagulation
• Paradoxical embolism (PFO with DVT)

Other vascular causes

• Vasculitis (infectious: neurosyphilis, TB; autoimmune: PAN, granulomatosis with polyangiitis; primary CNS vasculitis)
• Radiation vasculopathy (delayed effect after head/neck radiation)
• Moyamoya disease (progressive occlusion of terminal ICA with compensatory collateral vessel formation)

Cognitive domains affected (reflecting subcortical/frontal pattern in typical VaD)

• Executive dysfunction and slowed processing speed (most characteristic; reflects disruption of frontal-striatal circuits and white matter pathology)—patients struggle with multitasking, planning, task-switching, and processing complex information; marked slowing distinguishes VaD from Alzheimer disease where early memory loss predominates
• Memory impairment (typically less prominent early than in AD; more reflective retrieval deficit than encoding defect; may improve with cueing)—patients often perform better on recognition testing than free recall
• Language relatively preserved (unlike cortical dementias; anomia and dysarthria may occur with specific lesion locations)
• Visuospatial dysfunction (variable; more prominent with parietal infarcts)

Motor and neurological signs

• Gait disturbance ("vascular parkinsonism" or "marche à petits pas"—magnetic gait with short steps and preserved arm swing, reflecting basal ganglia-thalamic disruption; distinct from parkinsonian tremor-rigidity)
• Pseudobulbar palsy (emotional lability, dysarthria, dysphagia from bilateral corticobulbar tract involvement)—patients exhibit inappropriate laughing or crying unrelated to mood
• Focal neurological deficits (hemiparesis, hemianopia, aphasia depending on stroke location)—presence of motor signs distinguishes VaD from pure cognitive presentations
• Hyperreflexia and pathological reflexes (Babinski sign, snout reflex indicating corticospinal and frontal involvement)

Temporal pattern distinguishing VaD from other dementias

• Stepwise cognitive decline (classic presentation; abrupt worsening coinciding with recognized stroke events)—cognitive plateaus between events, unlike gradual decline in AD
• Acute-on-chronic pattern (most common in clinical practice; superimposed acute infarcts on chronic white matter damage)

Mood and behavioral manifestations

• Depression (>30% of VaD patients; may be primary consequence of striatal-limbic infarction or reactive to stroke awareness)
• Apathy (prominent with frontal and anterior cingulate involvement; may exceed depression severity)
• Emotional lability (pseudobulbar affect from corticobulbar disruption)
• Personality change (may seem less dramatic than in behavioral variant FTD)

Atypical presentations

• Insidious onset without recognized strokes (small-vessel disease accumulation)
• Progressive decline mimicking AD (extensive subcortical white matter disease without discrete infarcts)
• Selective cognitive deficits (e.g., isolated memory loss from thalamic infarction)
• Early-onset VaD with CADASIL presenting with migraines with aura in 20s-30s before dementia develops

Clinical diagnostic approach

• History and timeline (cardinal diagnostic element): Obtain detailed timeline documenting stroke events or vascular interventions (carotid endarterectomy, coronary bypass), acute versus insidious cognitive onset, stepwise versus gradual decline pattern, vascular risk factor burden, current medications. Collateral history from informant essential—patient may minimize or deny cognitive changes (anosognosia common with frontal lobe infarcts). Distinguish true dementia (functional impairment) from mild cognitive impairment (preserved function despite test deficits).

• Neuropsychological testing: Formal testing (if resources available) characterizes cognitive profile—executive and processing speed deficits with relatively preserved naming/language support subcortical pattern typical of VaD; depressed performance on Trails B (executive/attention) more than Trails A (basic processing); executive dysfunction on Wisconsin Card Sorting Test; slowed performance on digit symbol substitution. Montreal Cognitive Assessment (MoCA) particularly sensitive for executive/processing speed deficits (sensitivity ~88% for VaD vs ~70% for MMSE which misses frontal deficits). Ischemic Score (combining clinical features and imaging) moderately predicts VaD probability.

• Neuroimaging (mandatory for diagnosis confirmation):

• Large territorial infarcts (hypodensity on FLAIR/T2; hyperintensity on DWI if acute; chronic changes show gliosis)
• Lacunar infarcts (small punctate lesions <15 mm; deep gray matter or brainstem typical locations; may be silent clinically)
• Leukoaraiosis (white matter hyperintensities/WMH on FLAIR/T2): Fazekas scale grades severity (0=none, 1=punctate, 2=confluent in caps, 3=confluent extending to periventricular region); grade 2-3 associated with cognitive decline; extensive WMH even without discrete infarcts suggests small-vessel disease-predominant VaD
• Microhemorrhages (gradient echo/SWI sequence shows hypointense foci; associated with CAA or chronic hypertension)
• Perivascular spaces enlargement (T2-hyperintense spaces around penetrating vessels; marker of small-vessel disease burden)

• Imaging burden validation: Imaging findings must correlate with cognitive deficits—single lacunar infarct rarely explains dementia (must exclude alternative causes); thalamic or strategic lesions disproportionately impair cognition compared to cortical infarcts of similar volume; extensive white matter disease burden more reliably associated with VaD than single large infarct.

Diagnostic criteria (modified from NINDS-AIREN and DSM-5)

• Dementia (cognitive impairment sufficient to impair function; documented decline from baseline)
• Cerebrovascular disease on imaging (infarct, hemorrhage, or white matter disease burden)
• Temporal relationship between cerebrovascular event and cognitive decline (ideal but not always present with insidious small-vessel disease)
• Cognitive pattern consistent with vascular distribution (frontal-executive predominance)
• Absence of other explanations for dementia

Laboratory studies

• Complete metabolic panel: Screen for electrolyte abnormalities (hyponatremia from SIADH post-stroke), renal dysfunction (affects medication clearance), liver disease
• CBC: Anemia may worsen cerebral hypoperfusion; elevated WBC suggests active inflammation (vasculitis); thrombocytopenia raises hemorrhagic risk
• Lipid panel: LDL elevation and low HDL increase stroke risk; triglycerides >200 mg/dL associated with small-vessel disease
• Fasting glucose and HbA1c: Diabetes screening (diabetes in ~30% of VaD patients)
• TSH and B12 level: Screen for treatable reversible causes of cognitive impairment (hypothyroidism, B12 deficiency)
• Homocysteine (optional): Elevated levels (>15 μmol/L) increase small-vessel disease risk; B12/folate supplementation if elevated
• ESR and CRP (if vasculitis suspected): ESR >40 mm/hr or CRP >10 mg/L with CNS vasculitis
• RPR/VDRL: Screen for neurosyphilis if risk factors present

Differential diagnosis considerations

• Alzheimer disease (most important distinction): Memory loss is early/prominent feature (vs. preserved early memory in VaD); no imaging evidence of relevant cerebrovascular disease; insidious onset without stepwise pattern; gradual slowing in AD; normal or only mild white matter changes on MRI
• Mixed dementia (AD + VaD): Most common scenario—cognitive pattern and imaging favor one or other, but both pathologies present; treatment addresses both components
• Frontotemporal dementia: Early personality/behavioral changes >cognitive in bvFTD; prominent language deficits in PPA variants; younger age of onset; imaging shows focal anterior temporal or frontal atrophy (not vascular pattern); MRI lacks infarcts/extensive white matter disease
• Lewy body dementia: Prominent visual hallucinations and parkinsonism; fluctuating cognition; REM behavior sleep disorder; less prominent executive dysfunction; neuroimaging usually unremarkable
• Mild cognitive impairment from vascular disease (not dementia): Cognitive deficits present on testing but function preserved in ADLs; risk for progression to VaD if vascular disease advances
• Depression with cognitive impairment ("pseudodementia"): Mood symptoms precede cognitive complaints; neuropsychological pattern shows effort-dependent deficits; imaging may show white matter changes but insufficient burden; improves with antidepressant treatment

Scoring systems and prognostic markers

• Hachinski Ischemic Score (older tool; ≥7 suggests vascular etiology): Scores acute onset, stepwise progression, fluctuating course, nocturnal confusion, somatic complaints, depression, hypertension, history of stroke, focal neurological signs, focal EEG changes. Limited sensitivity/specificity but still referenced for board questions.
• Ischemic Vascular Dementia Score (IVD Score): Incorporates neuropsychological testing pattern, imaging features, and vascular risk factors; better predictive validity than Hachinski
• NINDS-AIREN criteria: Gold standard diagnostic framework; requires dementia plus imaging evidence of cerebrovascular disease plus relationship between two

Primary prevention and risk factor modification (foundation of VaD management)

• Antithrombotic therapy:
• Antiplatelet agents (first-line for non-cardioembolic vascular dementia): Aspirin 81-325 mg daily (number needed to treat ~67 to prevent one stroke annually); mechanism inhibits platelet COX-1 and thromboxane A2 production. Clopidogrel (75 mg daily) or dipyridamole-aspirin combination alternative if aspirin intolerant; clopidogrel equivalent efficacy to aspirin but no synergy with aspirin (avoid combination). Ticagrelor or prasugrel not indicated for primary stroke prevention.
• Anticoagulation (essential for cardioembolic sources): Warfarin (target INR 2-3)

Disease-related complications

• Recurrent stroke (emergency): the same arteriopathy that produced VaD keeps producing infarcts, so each new event drops cognition another step. Signal: abrupt focal deficit or acute cognitive/behavioral worsening — activate stroke pathway with immediate non-contrast head CT per AHA/ASA acute ischemic stroke guidance; do not attribute sudden change to "progression of dementia."
• Intracerebral hemorrhage (emergency): hypertensive lipohyalinosis and cerebral amyloid angiopathy weaken the same vessels; lobar microbleeds on SWI mark CAA and predict hemorrhage on antithrombotics. Signal: headache, vomiting, depressed consciousness with focal deficit.
• Aspiration pneumonia (potentially emergent): bilateral corticobulbar injury causes pseudobulbar dysphagia. Signal: coughing with meals, wet voice, new hypoxia/fever — formal swallow evaluation before oral intake after any new stroke.
• Falls and hip fracture: marche à petits pas plus postural instability and polypharmacy; signal is unexplained bruising or a witnessed fall.
• Post-stroke seizures and status epilepticus (emergency): cortical infarct gliosis is epileptogenic; signal is stereotyped spells or prolonged post-event confusion.
• Depression, apathy, and delirium: striatal-limbic disconnection; new fluctuating inattention should prompt an infection/metabolic workup rather than a dementia diagnosis label.
• Incontinence, malnutrition, pressure injury, and caregiver burnout in advanced disease.

Treatment-related complications

• Antiplatelet/anticoagulant bleeding: GI hemorrhage and ICH; risk rises with extensive microbleed burden — AHA/ASA secondary prevention guidance advises against combining aspirin with clopidogrel long-term.
• Overaggressive blood pressure lowering: watershed hypoperfusion and orthostatic syncope in patients with large-vessel stenosis; signal is postural lightheadedness or cognitive worsening after titration.
• Antipsychotics for agitation: FDA boxed warning for increased mortality and cerebrovascular events in elderly dementia patients; APA recommends nonpharmacologic behavioral management first.
• Cholinesterase inhibitors (off-label in VaD): vagotonic bradycardia, syncope, GI upset.
• Anticholinergics, benzodiazepines, and sedating bladder agents: worsen executive function and precipitate delirium.

• The classic stem: an elderly hypertensive diabetic with stepwise cognitive decline, focal neurologic signs (hyperreflexia, Babinski, hemiparesis), a magnetic gait with short shuffling steps, and pseudobulbar affect. Executive dysfunction and slowed processing dominate; memory improves with cueing.
• Single best next step for suspected VaD: MRI brain (FLAIR/T2 plus DWI and SWI) to document infarcts, leukoaraiosis, and microbleeds — the diagnosis requires imaging correlation, not clinical impression alone. If the change was abrupt, the next step is emergent non-contrast head CT to evaluate for new stroke or hemorrhage.
• The association examiners test: CADASIL — autosomal dominant NOTCH3 mutation, migraine with aura in the 20s–30s, recurrent subcortical infarcts, and confluent white matter disease with characteristic anterior temporal pole involvement; skin biopsy shows granular osmiophilic material. Suspect it in early-onset dementia with a family history and no vascular risk factors.
• Treatment is vascular, not cognitive: risk factor control (blood pressure, statin, glycemic control, smoking cessation) plus antiplatelet therapy for noncardioembolic disease and anticoagulation for atrial fibrillation, per AHA/ASA secondary stroke prevention guidance. Cholinesterase inhibitors and memantine are FDA-approved for Alzheimer disease, not VaD, and offer at best modest benefit here.
• Common distractor 1 — Alzheimer disease: early, prominent encoding memory loss that does not improve with cueing, insidious gradual decline, no focal deficits, and imaging without significant vascular burden. Mixed dementia is the most common real-world answer at autopsy.
• Common distractor 2 — normal pressure hydrocephalus: gait apraxia, urinary incontinence, and dementia with ventriculomegaly out of proportion to atrophy; improvement after high-volume lumbar puncture separates it from vascular parkinsonism.
• Common distractor 3 — pseudodementia: depression preceding cognitive complaints, effort-dependent testing, "I don't know" answers; treat the mood disorder.
• Do not give antipsychotics for agitation as a first move — FDA boxed warning for increased mortality and stroke in dementia.
• Hachinski Ischemic Score ≥7 favors a vascular etiology; a dated tool, but still fair game.