CHICAGO—Mild cognitive impairment (MCI) is more common among older men than among older women, according to findings presented at the 60th Annual Meeting of the American Academy of Neurology. These results held true after researchers accounted for age, educational level, marital status, and disease burden, reported Rosebud O. Roberts, MD, who is an Associate Professor of Epidemiology at the Mayo Clinic in Rochester, Minnesota.
MCI was defined as impairment in one or more cognitive domains or an overall decline of cognitive abilities that is greater than would be expected for age and education but insufficient to interfere with social and work function, said Dr. Roberts. A number of studies had looked at MCI prevalence and reported inconsistent findings regarding sex differences. A few of these studies had limitations, however, as some applied MCI criteria to previously collected data, while others used study samples that were not representative of the general population.
MCI in a Population-Based Setting
Dr. Roberts and colleagues’ investigation included 2,050 men and women ages 70 to 89 from Olmsted County, Minnesota. At baseline, 52% were ages 80 to 89, 51% were male, 47% had less than 12 years of education, and 61% were married. Evaluations consisted of face-to-face assessments by nurses, neuropsychologists, and physicians regarding the participants’ memory, executive function, language, and visuospatial skills. Overall, the researchers found that 73.6% of subjects had normal cognition, 16.5% were diagnosed with MCI, and 9.9% had previously undiagnosed dementia.
The prevalence of MCI increased with age—10% in those ages 70 to 79 and 25% in those ages 80 to 89. In women, MCI was found in 8% of 70- to 79-year-olds and in 19% of those ages 80 to 89. In men, the prevalence increased from 12% to 40% in the two age-groups, respectively.
“The higher prevalence of MCI in men was an unexpected finding, so we performed additional analyses to make sure that it wasn’t a chance finding,” said Dr. Roberts.
When comparing men and women, the researchers found that men were 44% more likely to have MCI. After adjusting for age and education, the investigators found that men were 67% more likely than women to have MCI. Also, taking marital status and disease burden into account did not change the results.
“We found that 80% of men were married, compared with 40% of the women,” said Dr. Roberts. “We thought that perhaps marital status had an impact, or that men would be sicker, but when we analyzed the data according to marital status and disease burden, the greater prevalence of MCI in men compared to women persisted.”
Dr. Roberts suggested some possible explanations for these findings, including that the sex differences may be related to risk factors in middle age that affect the development of cognitive impairment in late life and that women may progress more quickly than men to dementia, without going through an MCI phase. Another factor may be that more women with MCI are dying compared with men, she said.
Dr. Roberts’ group plans to follow these subjects over time and analyze whether men develop MCI at a faster rate than women.
—Alice Goodman