Mild cognitive impairment (MCI) among the elderly had been previously viewed as relatively benign, however now experts believe it should not be viewed as a normal part of the aging process, but rather as the beginning of a far more serious disease process. A recent study found that even minor loss of cognitive function appears to be an indicator of one or both of the neurologic diseases Alzheimer's or cerebral vascular disease.

In the study, which involved following subjects until they developed mild cognitive impairment or dementia and then died, participants took tests that measured their memory, language, attention and other cognitive abilities each year. After death, the researchers examined brain tissue from 180 people--37 with mild cognitive impairment, 60 without cognitive impairment and the rest with dementia--and measured the amount of Alzheimer's disease pathology and cerebral infarcts (strokes). It was found that:

• More than half of the 37 people with MCI met pathologic criteria for Alzheimer's disease.
• Close to one-third of those with MCI had cerebral infarcts.
• Less than one-quarter of the participants had neither of the pathologies.
  

On a positive note, researchers found that one-third of those with an average age of 85 did not experience signs of cognitive decline, despite the fact that half of them had significant Alzheimer's disease pathology and close to one-quarter had cerebral vascular disease. Researchers believe these people have a sort of "reserve capacity" that allows them to stay cognitively sharp even though their brains showed signs of disease.

However, the number of people who experience cognitive impairments because of Alzheimer's disease and cerebral vascular disease is likely much larger than estimates show, researchers said.

Neurology March 8, 2005; 64:834-841

Science Daily March 17, 2005