Erfan Bashar
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Vascular Dementia and Reversible Dementias

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Educational scope notice: This is a study note for medical students, not medical advice, diagnosis, or treatment guidance. Clinical management should follow local protocols and current guidelines.

Vascular dementia accounts for roughly 10–20% of dementia and matters because its treatment differs from Alzheimer disease: control the vascular risk factors rather than relying on cholinesterase inhibitors. The classic course is stepwise, with each step marking a new ischaemic event, and focal neurological signs such as hemiparesis, Babinski responses, or aphasia accompany the cognitive decline. Cognitive slowing with pyramidal signs in a hypertensive patient is the textbook picture.

Diagnostic requirements

Vascular cognitive impairment needs a strict temporal link: a clinical stroke occurs, cognition worsens after the stroke rather than before, imaging shows vascular lesions that explain the pattern, and no better explanation fits. Because mixed pathology is common, comorbid Alzheimer disease should be considered even when vascular features dominate, and amyloid PET can settle the question when it changes management.

Subtypes

  • Post-stroke dementia follows a clear vascular event, and the timing is the diagnosis: normal cognition before, decline after.
  • Small vessel disease from hypertensive arteriopathy damages deep white matter, producing executive dysfunction, slowed gait, and urinary symptoms that can resemble normal pressure hydrocephalus.
  • A strategic infarct is a single stroke in a critical relay such as the thalamus, caudate, or hippocampus that causes disproportionate cognitive loss.
  • Cerebral amyloid angiopathy is amyloid in cortical vessel walls, described below.

MRI is essential. Severe white matter hyperintensity on T2/FLAIR in an older hypertensive patient marks small vessel disease; disproportionate ventricular enlargement points toward normal pressure hydrocephalus; microbleed location separates amyloid angiopathy (lobar) from hypertensive disease (deep).

Cerebral amyloid angiopathy

In amyloid angiopathy, amyloid-β replaces smooth muscle and elastic tissue in cortical and leptomeningeal vessel walls, leaving rigid, brittle tubes prone to lobar haemorrhage. Imaging shows lobar microbleeds on blood-sensitive sequences, sometimes with cortical superficial siderosis, white matter hyperintensity, or visible perivascular spaces.

The treatment consequence is exceptional: antiplatelets and anticoagulants, the default vascular protection elsewhere, increase haemorrhage risk here and are generally avoided. The rule stays a default rather than an absolute, since each patient weighs clotting risk against haemorrhage risk.

Normal pressure hydrocephalus

Normal pressure hydrocephalus is one of the few reversible dementias. Impaired cerebrospinal fluid absorption enlarges the ventricles out of proportion to cortical atrophy, stretching the periventricular circuits for gait, bladder control, and executive function.

The triad is gait apraxia (wide-based, shuffling, magnetic gait with difficulty initiating and turning, usually first and most shunt-responsive), urinary urgency progressing to incontinence, and slowed thinking with executive dysfunction. Diagnosis pairs the imaging pattern with a tap test: remove cerebrospinal fluid, reassess gait and balance, and sustained improvement predicts benefit from a ventriculoperitoneal shunt. A negative tap test does not rule out shunt benefit.

Reversible mimics

These conditions can look like dementia but improve with treatment:

  • Depression, where mood decline comes first and encouragement can still unlock knowledge;
  • drug-induced impairment from anticholinergics or benzodiazepines, which can take weeks to months to resolve after withdrawal;
  • hypothyroidism, reversed by thyroid hormone replacement;
  • B12 deficiency, reversed by supplementation before damage becomes permanent;
  • thiamine deficiency, where acute Wernicke encephalopathy (confusion, ataxia, ophthalmoplegia) can harden into chronic Korsakoff amnesia;
  • alcohol-related impairment, helped by abstinence and thiamine.

Baseline screening with brain MRI, B12, and thyroid function tests catches these before a neurodegenerative label sticks.

Evidence anchors

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