The prevalence of mild forms of cognitive impairment among the elderly increases with age and may be associated with cerebrovascular disease, depression, and racial factors, according to an article in the October issue of the Archives of Neurology.

Mild cognitive impairment is characterized by demonstrable cognitive impairment including memory problems but excludes dementia, according to background information. Patients with mild cognitive impairment are at a higher risk for developing dementia, especially Alzheimer disease.

Oscar L. Lopez, M.D., and his American colleagues determined the prevalence of mild cognitive impairment and examined risk factors associated with it among participants in the Cardiovascular Health Study Cognition Study. The Study included 3,608 adults who had a magnetic resonance imaging brain scan between 1991 and 1994 and underwent detailed neuropsychological, neurological, and medical evaluations between 1998 and 1999. The researchers conducted further examinations on 927 participants who lived near their medical center. Patients with mild cognitive impairment in this subset were classified as having either an amnestic-type (characterized by difficulty in remembering past events) or a multiple cognitive deficits-type condition based on individual symptoms.

The researchers found that the overall prevalence of among Study participants was 19 percent (465 of 2,470 participants who were alive in 1998-1999). The prevalence increased with age from 19 percent in participants younger than 75 years old to 29 percent in those older than 85 years. In the subset, the overall prevalence was 22 percent (130 of 599 patients still alive in 1998-1999). Of the affected patients, 6 percent had amnestic-type and 16 percent had multiple cognitive deficits-type impairment.

The researchers also found that mild cognitive impairment was associated with African American background, low educational level, low Modified Mini-Mental State Examination score, and low Digit Symbol Test score, cortical atrophy, infarcts on imaging, and depression.

The authors noted that "Most of the participants with mild cognitive impairment had comorbid conditions that may affect their cognitive functions."