What is mild cognitive impairment (MCI) in patients with Alzheimer disease (AD)?

Updated: May 09, 2019
  • Author: Shaheen E Lakhan, MD, PhD, MS, MEd; Chief Editor: Jasvinder Chawla, MD, MBA  more...
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Answer

The pathologic changes associated with AD begin in the entorhinal cortex, which is near the hippocampus and directly connected to it. AD then proceeds to the hippocampus, which is the structure that is essential to the formation of short-term and long-term memories (see the images below). Affected regions begin to atrophy. These brain changes occur decades before any signs or symptoms appear.

Memory loss, the first visible sign, is the main feature of amnestic mild cognitive impairment (MCI). Many scientists think MCI is often an initial, transitional clinical phase between normal brain aging and AD. For more information, see the Medscape Reference article Mild Cognitive Impairment.

Preclinical Alzheimer disease. Image courtesy of N Preclinical Alzheimer disease. Image courtesy of NIH.
Preclinical Alzheimer disease. Image courtesy of N Preclinical Alzheimer disease. Image courtesy of NIH.

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