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Condition/Disorder Synonyms

  • Alzheimer's dementia

ICD-9-CM Code

  • 331.0 Alzheimer's disease

ICD-10-CM Code

  • G30.9 Alzheimer's disease, unspecified

Preferred Practice Pattern

Key Features


  • A degenerative neurologic disorder characterized by progressive dementia

  • Results in inability to care for oneself or interact in the environment

Essentials of Diagnosis

  • Insidious onset

  • Gradual development of forgetfulness that degenerates into other failures of cerebral function

  • Concise pathology that accounts for 50% of all dementia cases2

General Considerations

  • Definitive diagnosis is made upon autopsy.

  • Imaging in late stages of the disease reveals hippocampal and frontal lobe atrophy.

  • Early in the disease process, all other possible causes of dementia are ruled out in order to diagnose Alzheimer's disease.


  • Onset primarily occurs at age greater than or equal to 60

  • Women three times more likely than men

  • Weak genetic link, most commonly idiopathic

Clinical Findings

Signs and Symptoms

  • Loss of cognitive function, most commonly in the following sequence:

    • - Abstract thinking

    • - Judgment and problem solving

    • - Language for communication

    • - Personality changes

  • Eventually the person loses ability to perform self-care or activities of daily living (ADLs).

  • Although the ability to perform automatic movements is maintained, the understanding of purpose behind the activities is lost.

  • As the person loses this understanding, he/she may participate in less physical activity, resulting in disuse atrophy.

Functional Implications

  • Loss of the following activities occur:

    • - Interaction in the environment

    • - Memory and goal-directed behavior

    • - Independence with ADLs

    • - Strength and mobility

Possible Contributing Causes

  • Unknown, primarily idiopathic

Differential Diagnosis

  • Stroke (multi-infarct dementia)

  • Tumor

  • Subdural hematoma

  • Hydrocephalus

  • Dementia of AIDS

  • Paraneoplastic limbic encephalitis

  • Nutritional deficiencies

  • Metabolic disorders

  • Pseudodementia of depression

  • Supranuclear palsy

  • Lewy body disease

  • Age-related dementia

Means of Confirmation or Diagnosis

Laboratory Tests

  • Cerebrospinal fluid (CSF) for protein analysis

  • Neuropsychological testing


  • Computed tomography (CT) of the brain

  • Magnetic resonance imaging (MRI) of the brain

  • Single-photon emission computed tomography (SPECT) for hypoperfusion in the parietal and temporal regions

  • Positron emission tomography (PET) scan for abnormal brain proteins

Diagnostic Procedures

  • Electroencephalography (EEG) for brain function

Findings and Interpretation

  • In advanced stages of Alzheimer disease, MRI will show frontal lobe atrophy.

  • In early stages, EEG may show resting ...

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