Vascular dementias

Vascular dementias encompass all types of dementia caused by cerebrovascular, cardiovascular diseases, or blood flow issues. They are considered the second leading cause (25 to 50% of cases) of dementia in developed countries and the first in developing countries. Approximately 30% of patients who have suffered a stroke will subsequently develop dementia (RR = 3 to 6).

Sharing age as a major risk factor with other types of dementias, they co-exist with another cause of dementia (mixed dementias, primarily degenerative and vascular) in more than half of cases. As a result, they may be underdiagnosed (for example: diagnosing Alzheimer’s disease while neglecting a vascular cause as a co-factor of the dementia syndrome).

Overall, they have a poor prognosis, although some etiologies are amenable to treatment that may halt their progression.

The median survival after diagnosis for isolated vascular dementia is 3.9 years, and 5.4 years for mixed dementias (compared to 7.1 years for Alzheimer’s disease and 11 years for controls).

Etiologies

• Small vessel disease → slow progression or fluctuating with sudden worsens depending on the case
  • Atherosclerosis
  • Cerebral amyloid angiopathy → presence of micro and macro-bleeds (++ lobar) associated with subcortical ischemic lesions, more frequently associated with Alzheimer's disease.
  • Rare conditions: CADASIL (++ with history of migraines and seizures, early onset), CARASIL, MELAS, cerebral vasculitis, systemic diseases, antiphospholipid syndrome, collagen diseases, …
• Large and medium vessel disease → often abrupt progression, in fits following repeated strokes
  • Massive infarcts, multiple cortical-subcortical infarcts, strategic infarcts (e.g.: bithalamic infarct → severe memory disorders, apathy, indifference, attention disorders ± ophthalmoplegia,…)
  • Atherothrombotic, athero-embolic, cardio-embolic origins, vasculitis of medium and large vessels
  • Hemorrhages → abrupt progression
  • Cerebral venous thrombosis → generally progressive course, rare

Aside from rare etiologies (inflammatory or hereditary), the main risk factors are: age, hypertension, diabetes, hypercholesterolemia, sedentary lifestyle, alcohol and tobacco use, ischemic heart diseases, atrial fibrillation.

Clinical Features

Two possible evolutionary patterns:

• Abrupt in the context of a recent stroke
• Insidious, often "stepwise"

The dementia picture often predominates in a "frontal," behavioral manner. Frequent associations with early focal deficits.

Possible insidious progression towards a "multi-lacunar state" (dementia, pseudobulbar syndrome: dysarthria – dysphagia – spastic laughter and crying, gait disorders "vascular parkinsonism," mood disorders) in cases of small vessel disease.

Complementary Examinations

• Systematic:

• Angio-CT or brain angio-MRI → types of lesions, suggestion of particular etiologies
• Search for cardiovascular risk factors (CVRF): MAPA, Holter monitoring, Doppler ultrasound of the neck vessels, laboratory tests
• Examinations conditioned by the degree of clinical suspicion of a rare etiology or potentially curable differential diagnosis, age, and cognitive state of the patient:
  • Additional laboratory tests
  • Lumbar puncture with pressure measurement
  • Conventional angiography
  • Brain PET scan

Diagnosis and differential diagnosis

The positive diagnosis is difficult to establish in the absence of validated criteria. Indicative signs include:

• Poorly controlled CVRF, history of stroke
• Suggestive lesions on imaging (++ subcortical, multi-lacunar state)
• Staircase clinical pattern, sudden onset, fluctuating evolution, episodes of confusion
• Association with focal deficits, frontal syndrome, executive dysfunctions, or other cognitive impairments prominently affecting memory
• Awareness of the problem (anosognosia less frequent than in degenerative dementias)
• Absence of clinical, biological, and radiological arguments for another etiology

The differential diagnosis includes other dementias and "pseudo-dementias": degenerative dementias (++ Alzheimer’s disease), alcoholic dementias, normal pressure hydrocephalus, psychiatric disorders (++ depression), brain tumors, paraneoplastic syndromes, metabolic encephalopathies, systemic infectious or inflammatory diseases, …

Therapeutic Management - Treatments

• In all cases: management of cardiovascular risk factors to limit progression. +++ hypertension (the only factor for which effective control is demonstrated) > diabetes, alcohol and tobacco use, hypercholesterolemia, lifestyle and dietary measures...
• Antiplatelet therapy based on fall risk and the hemorrhagic/ischemic lesion ratio
• Etiological treatment if possible: embolic causes, thrombophilia, vasculitis, systemic diseases, vascular malformations, large vessel stenosis, inflammatory amyloid angiopathies, etc
• Debated effectiveness of cholinesterase inhibitors (see Alzheimer's disease), recommended for consideration – not reimbursed for this indication.
• Paramedical care similar to other dementias (see Alzheimer's disease article).

Author

Dr Shanan Khairi, MD

Bibliography

Bradley WG et al., Neurology in clinical practice, 5th ed., Butterworth-Heinemann, e-dition, 2007

EMC, Traité de Neurologie, 2018

Smith EE, Etiology, clinical manifestations, and diagnosis of vascular dementia, UpToDate, 2022