Research Review

MCI More Common in Men Than Women

Older men may be at risk of developing mild cognitive impairment (MCI), often a precursor to Alzheimer's disease, earlier in life than older women, according to a study appearing in Neurology. The study raises the question of whether there may be a gender difference in the development and progression of MCI.

Scientists evaluated the cognitive health of 1,969 dementia-free older people and found 16% showed signs of MCI, a condition usually marked by memory problems or other cognitive problems greater than those expected for their age. Prevalence was greater among the older participants and was consistently higher in men than women across all age ranges.
 
"Because evidence indicates that Alzheimer's disease may cause changes in the brain one or two decades before the first symptoms appear, there is intense interest in investigating MCI and the earliest stages of cognitive decline," says National Institute on Aging Director Richard J. Hodes, MD. "While more research is needed, these findings indicate that we may want to investigate differences in the way men and women develop MCI, similar to the way stroke and cardiovascular disease risk factors and outcomes vary between the sexes."

The researchers conducted in-person evaluations of 1,969 randomly selected people from all 70- to 89-year-olds living in Olmsted County, Minn. The group was evenly split between men and women. Each individual received a neurological evaluation and neuropsychological testing. A panel then reviewed those data plus other information, such as health history and occupation/education levels, to reach a diagnosis. Sixteen percent were diagnosed with MCI; these individuals displayed either amnestic MCI, where memory is impaired, or nonamnestic MCI, where different cognitive problems arise, such as with language.

Results of the study indicated that:

• Overall, MCI was more prevalent in men (19%) than in women (14%), even after adjusting for several demographic variables and clinical factors, such as hypertension and coronary artery disease.

• Of the 16% affected with MCI, over twice as many people had the amnestic form that usually progresses to Alzheimer's disease and the prevalence rate was higher in men than in women.

• MCI prevalence was higher among people with the APOE e4 gene, a known risk factor for late-onset Alzheimer's, a form of the disease that usually occurs at age 65 or older.

• A greater number of years spent in school was significantly associated with decreased MCI prevalence, from 30% among participants with less than nine years of education to just 11% in those with more than 16 years of education.

• MCI prevalence was higher in participants who never married, as opposed to those currently or previously married.

The researchers noted that estimates of MCI prevalence vary in studies conducted around the world but generally fall into a range of 11% to 20%. The Mayo team's evaluation of participants included detailed in-person assessments that helped to capture the subtle changes in daily function that may mark the onset of MCI. The researchers also noted that the study's limitations include a relatively low participation rate by Olmstead County residents and the fact that the population is predominantly white. Thus, these findings may not apply to other ethnic groups.

— Source: National Institutes of Health