Dementia is a topic covered in the 5-Minute Clinical Consult.

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  • DSM-5 classifies dementias under neurocognitive disorders (major and mild).
  • Evidence of cognitive decline from previous level of performance in one of cognitive domains (attention, executive function perceptual-motor, social cognition and memory). The cognitive deficits interfere significantly with ADLs (for major only) and do not occur exclusively in the context of delirium or any other mental disorder.
  • DSM-5 specifies the cause of neurocognitive decline secondary to the following:
    • Alzheimer dementia (AD)
      • Progressive cognitive decline; most common age >65 years
    • Vascular dementia (VaD)
      • Usually correlated with a cerebrovascular event and/or cerebrovascular disease
      • Stepwise deterioration with periods of clinical plateaus
    • Lewy body dementia
      • Fluctuating cognition associated with parkinsonism, hallucinations and delusions, gait difficulties, and falls
    • Frontotemporal dementia
      • Language difficulties, personality changes, and behavioral disturbances
    • Creutzfeldt-Jakob disease (CJD)
      • Very rare; rapid onset
    • HIV dementia
    • Substance-/medication-induced neurocognitive disorder


  • In patients age ≥65 years
    • AD: 5–10% (age 65 to 70 years); 25% (≥70 years)
    • VaD: 0.2% (age 65 to 70 years); up to 16% (≥70 years)
    • Other: 13%
  • Estimated 5.4 million Americans had AD in 2010.
    • 5 million >65 years of age; 200,000 <65 years
    • Prevalence expected to double by 2030

Etiology and Pathophysiology

  • AD: involves β-amyloid protein accumulation and/or neurofibrillary tangles (NFTs), synaptic dysfunction, neurodegeneration, and eventual neuronal loss
  • Age, genetics, systemic disease, smoking, and other host factors may influence the β-amyloid accumulation and/or the pace of progression toward the clinical manifestations of AD.
  • VaD: cerebral atherosclerosis/emboli with clinical/subclinical infarcts

  • AD: positive family history in 50%, but 90% AD is sporadic: APOE4 increases risk but full role unclear.
  • Familial/autosomal dominant AD accounts for <5% AD: amyloid precursor protein (APP), presenilin-1 (PSEN-1), and presenilin-2 (PSEN-2).

Risk Factors

  • Age; sex: female > male
  • Genetic predisposition
  • Hypertension: AD; VaD
  • Hypercholesterolemia: AD; VaD
  • Diabetes: VaD
  • Cigarette smoking: VaD
  • Endocrine/metabolic abnormalities: hypothyroidism, Cushing syndrome; thiamine and vitamin B12 deficiency
  • Chronic alcoholism, other drugs
  • Lower educational status
  • Head injury early in life
  • Sedentary lifestyle

General Prevention

  • Treat reversible causes of dementia, such as drug-induced, alcohol-induced, and vitamin deficiencies.
  • Treat hypertension, hypercholesterolemia, and diabetes.
  • No evidence for statins (or any other specific medication) to prevent onset of dementia (1)[A]
  • BP control and low-dose aspirin may prevent or lessen cognitive decline in VaD.

Commonly Associated Conditions

  • Anxiety and major depression
  • Psychosis (delusions; delusions of persecution are common)
  • Delirium
  • Behavioral disturbances (agitation, aggression)
  • Sleep disturbances

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