• Clinical syndrome defined by progressive deterioration involving one or more cognitive domains (language, memory, complex attention, perceptual-motor, social cognition) that is severe enough to interfere with activities of daily living and independence due to alteration in cortical brain function
  • A chronic and progressive form of organic brain syndrome
  • Over 50 different causes
  • Most common cause is Alzheimer dementia (between 60–80% of cases), followed by vascular dementia, mixed dementia, and dementia with Lewy bodies
  • Affects between 5–16% of individuals between age 65–85 and between 30–40% in people >85 yr old
  • Incidence of dementia has decreased in past few decades, although there has been a rise in absolute number of patients with dementia worldwide
  • Characterized by gradual decline in cognitive functioning:
    • Generally evolves over period of years
    • Course is highly variable, months to years in duration
    • Rapid decline indicative of other causes, or rare rapid onset causes of dementia (prion diseases, progressive supranuclear palsy)
  • Variable hereditary
    • Increased risk of Alzheimer disease in first-degree relatives of patients with Alzheimer
    • Apolipoprotein ε4 is the only well-established mutation with late-onset Alzheimer


  • Primary dementia:
    • Cortical (Alzheimer disease, frontotemporal dementia)
    • Subcortical (Huntington disease, Parkinson disease, progressive supranuclear palsy)
  • Secondary dementia:
    • Cerebrovascular disease (multi-infarct dementia)
    • Toxic, metabolic, nutritional derangements
    • Prion disorders (Creutzfeldt–Jakob or bovine spongiform encephalopathy and variants)
    • Infectious agents (HIV, syphilis, encephalitis)
    • Vasculitis (systemic lupus erythematosus, thrombotic thrombocytopenic purpura)
    • Traumatic (chronic subdural hematomas, pugilistic dementia, chronic traumatic encephalopathy)
    • Structural (normal pressure hydrocephalus, brain masses)
    • Binswanger disease
  • Reversible (∼15%) causes include normal pressure hydrocephalus, medications, intracranial masses, and alcohol abuse syndromes
  • Pseudodementia:
    • Depression in elderly can present with dementia-like symptoms
    • Common in mildly demented patients, look for pin-point event with short duration of symptoms
    • Generally with history of psychiatric conditions, emphasis on failures and disabilities

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