The incidence of MCI differs by subtype and is higher in men: The Mayo Clinic Study of Aging

Rosebud O. Roberts, M.B.Ch.B. with the Division of Epidemiology, discusses a study that measured the incidence of MCI and its subtypes using published criteria. Results showed a statistically significant difference between incidence rates among men and women. The study also found that individuals with only a high school education developed either aMCI or naMCI at a higher rate than those with some higher education.

The study was published in the Jan. 25, 2012, issue of Neurology.

ABSTRACT
Objective
Although incidence rates for mild cognitive impairment (MCI) have been reported, few studies were specifically designed to measure the incidence of MCI and its subtypes using published criteria. This study estimates the incidence of amnestic MCI (aMCI) and nonamnestic MCI (naMCI) in men and women separately. 

Methods
A population-based prospective cohort of Olmsted County, Minn., residents age 70 to 89 on Oct. 1, 2004, underwent baseline and 15-month interval evaluations that included:

• The Clinical Dementia Rating scale
• A neurologic evaluation
• Neuropsychological testing

A panel of examiners blinded to previous diagnoses reviewed data at each serial evaluation to assess cognitive status according to published criteria. 

Results
Among 1,450 subjects who were cognitively normal at baseline, 296 developed MCI.

The age- and sex-standardized incidence rate of MCI was 63.6 (per 1,000 person-years) overall, and was higher in men (72.4) than women (57.3) and for aMCI (37.7) than naMCI (14.7).

The incidence rate of aMCI was higher for men (43.9) than women (33.3), and for subjects with ≤12 years of education (42.6) than higher education (32.5).

The risk of naMCI was also higher for men (20.0) than women (10.9) and for subjects with ≤12 years of education (20.3) than higher education (10.2).

Conclusions
The incidence rates for MCI are substantial. Differences in incidence rates by clinical subtype and by sex suggest that risk factors for MCI should be investigated separately for aMCI and naMCI, and in men and women.

Authors
Rosebud.O. Roberts, M.B.Ch.B., Yonas E. Geda, M.D., David S. Knopman, M.D., Ruth H. Cha, Vernon (Shane).S. Pankratz, Ph.D., Bradley F. Boeve, M.D., Eric G. Tangalos, M.D., Robert J. Ivnik, Ph.D., L.P., Walter A. Rocca, M.D., Ronald C. Petersen, M.D., Ph.D.

 

Source: http://physicianupdate.mayoclinic.org/2012/02/17/the-incidence-of-mci-differs-by-subtype-and-is-higher-in-men-the-mayo-clinic-study-of-aging/

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