What are the preclinical mild cognitive impairment and dementia stages used in Alzheimer disease diagnosis?

Alzheimer disease is categorized into three distinct stages: preclinical, mild cognitive impairment (MCI), and Alzheimer dementia. For the purpose of clinical diagnosis, MCI and dementia are the most relevant stages.1

Preclinical Stage

The preclinical stage recognizes that the disease process begins before clinical symptoms become apparent. Current diagnostic efforts anticipate future advancements that will allow for identification during this asymptomatic phase.1

Mild Cognitive Impairment (MCI)

MCI serves as a transitional stage between normal aging and dementia. It is subdivided into two types:
* Amnestic MCI: Characterized by noticeable memory dysfunction, while reasoning, judgment, and perception remain normal.1
* Nonamnestic MCI: Impairments in language, attention, and perception are more prominent than memory deficits.1

Alzheimer Dementia

As the condition progresses to dementia, memory loss intensifies, and other cognitive and motor skills deteriorate. Patients often experience mood instability, including irritability, anxiety, or depression. Advanced stages involve a loss of mobility and bodily control, ultimately leading to death.1