Major or Mild Neurocognitive Disorder due to Alzheimer's Disease

Prevalence

• The prevalence of overall dementia (major NCD) rises steeply with age.

• In high-income countries, it ranges from 5% to 10% in the seventh decade to at least 25% thereafter.

• The percentage of dementias attributable to Alzheimer's disease ranges from about 60% to over 90%, depending on the setting and diagnostic criteria.

Symptoms

• The criteria are met for major or mild neurocognitive disorder.

• There is insidious onset and gradual progression of impairment in one or more cognitive domains.

• Criteria are met for either probable or possible Alzheimer’s disease as follows:

For major neurocognitive disorder

Probable Alzheimer’s disease is diagnosed if either of the following is present; otherwise, possible Alzheimer’s disease should be diagnosed.

• Evidence of a causative Alzheimer’s disease genetic mutation from family history or genetic testing.

• All three of the following are present:

  1. Clear evidence of decline in memory and learning and at least one other cognitive domain.

  2. Steadily progressive, gradual decline in cognition, without extended plateaus.

  3. No evidence of mixed etiology.

For mild neurocognitive disorder

• Probable Alzheimer’s disease is diagnosed if there is evidence of a causative Alzheimer’s disease genetic mutation from either genetic testing or family history.

• Possible Alzheimer’s disease is diagnosed if there is no evidence of a causative Alzheimer’s disease genetic mutation from either genetic testing or family history, and all three of the following are present:

  1. Clear evidence of decline in memory and learning.

  2. Steadily progressive, gradual decline in cognition, without extended plateaus.

  3. No evidence of mixed etiology.

  4. The disturbance is not better explained by cerebrovascular disease, another neurodegenerative disease, the effects of a substance, or another mental, neurological, or systemic disorder.