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For further information, see CMDT Part 24-15: Dementia

Key Features

Essentials of Diagnosis

  • Progressive decline of intellectual function

  • Loss of short-term memory and at least one other cognitive deficit

  • Deficit severe enough to cause impairment of function

  • Not due to delirium or psychiatric disease

  • Major risk factors

    • Age

    • Family history

    • Lower educational level

    • Diabetes mellitus

    • Cigarette smoking

    • Hypertension

    • Obesity

    • History of significant head injury

    • Hearing loss

    • Female sex

  • Vitamin D deficiency and chronic sleep deprivation may also increase the risk for dementia

General Considerations

  • Defined as a progressive, acquired impairment in multiple cognitive domains, at least one of which is memory, that is severe enough to compromise work or social life

  • "Mild cognitive impairment" describes a decline that has not resulted in a change in the level of function

  • Patients have little cognitive reserve and can have acute cognitive or functional decline with a new medical illness

  • Dementia is distinct from delirium and depression and other psychiatric disease, and in the elderly may coexist with them

    • Delirium is an acute confusional state that often occurs in response to an identifiable trigger

      • Typically involves fluctuating level of arousal and improves after removal or treatment of the precipitating factor

    • Depression and other psychiatric disease sometimes lead to complaints of impaired cognition (pseudodementia)

      • Symptoms should improve with appropriate psychiatric treatment

      • Evidence suggests that a persistent, untreated mood disorder may predispose to the development of an age-related dementia

      • Psychiatric symptoms can clearly exacerbate cognitive impairment in patients who already have dementia

  • Rapidly progressive dementia (eg, Jakob-Creutzfeldt disease) is defined as obvious decline over a few weeks to a few months


  • Prevalence of Alzheimer dementia in the United States

    • Doubles every 5 years in the older population, reaching 30–50% at age 85

    • Predicted to be 15 million by 2060

  • Typically begins after age 60, and the prevalence doubles approximately every 5 years thereafter

  • Women suffer disproportionately, as patients (even after age adjustment) and as caregivers

  • Alzheimer disease accounts for two-thirds of cases of dementia in the United States, with vascular dementia (either alone or combined with Alzheimer disease) accounting for much of the rest

Clinical Findings

Symptoms and Signs

  • Memory impairment with at least one or more of the following

    • Aphasia (typically, word finding difficulty)

    • Apraxia (inability to perform previously learned tasks)

    • Agnosia (inability to recognize objects)

    • Impaired executive function (poor abstraction, mental flexibility, planning, and judgment)

  • Alzheimer disease

    • Typical earliest deficits are in memory and visuospatial abilities

    • Social graces may be retained despite advanced cognitive decline

    • Personality changes and behavioral difficulties (wandering, inappropriate sexual behavior, aggression) may develop as the disease progresses

    • Hallucinations, delusions, and symptoms of depression often occur as dementia worsens

    • End-stage disease characterized by

      • Near-mutism

      • Inability to sit up

      • Inability to hold up the head


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