Mild Cognitive Impairment More Common in Men Than in Women

May 1, 2008 (Chicago, Illinois) — A new prevalence study using population-based data from Olmstead County suggests that men have a 67% increased risk for mild cognitive impairment (MCI) relative to women.

"We concluded that the prevalence of MCI in the general population of 80- to 89-year-olds in our population is high," around 16.5%, Rosebud Roberts, MD, from the Mayo Clinic in Rochester, Minnesota, told a press conference here. "We also concluded that the prevalence of MCI is higher in men compared to women."

Their findings were presented here at the American Academy of Neurology 60th Annual Meeting.

Previous Findings at Odds

Reports of sex differences in the prevalence of MCI have been inconsistent, Dr. Roberts said, with some finding it to be more common in men, a few more common in women, and some finding no difference. Some of these studies have applied MCI criteria to previously collected data or used non–population-based cohorts such as clinic populations, but the question has not been fully evaluated in a population-based setting using published diagnostic criteria.

In this study, the researchers used data from the Mayo Clinic Study of Aging, a longitudinal study in Olmstead County, Minnesota, randomly selecting residents of both sexes who were between 70 and 89 years of age on October 1, 2004. They selected 2050 participants to represent equal numbers of men and women and equal numbers from 70 to 79 and 80 to 89 years of age.

Subjects underwent a structured interview including the Clinical Dementia Rating Scale, a neurological evaluation by a physician, and neuropsychological testing. Results were reviewed by a panel of neurologists and neuropsychologists, and a diagnosis of normal cognition, MCI, or dementia was made by specified criteria.

They found about 74% of subjects had normal cognition, 16.5% had MCI, and almost 10% had a new diagnosis of dementia.

Prevalence of MCI and Dementia

Further analyses included the 1969 subjects who were not demented; 14 other subjects were excluded because they were unable to complete the evaluation. Of these 52% were aged 80 to 89 years, 51% were male, 47% had 12 years of education or less, and 61% were married, she noted.

"When we looked at the prevalence by age, the prevalence in men and women combined increased with increasing age, from about 10% in 70- to 74-year-olds to about 25% in 85- to 89-year-olds," Dr. Roberts said. When this analysis was limited to women, MCI increased from about 8% in the youngest age group to 19% in the oldest group. A similar pattern was seen in men, but the prevalence of MCI was higher than for women, increasing from about 12% to 40% in the oldest group.

When they adjusted for age and education, the odds ratio was even higher for men vs women and was unchanged by additional adjustment for marital status or burden of disease.

Risk for MCI for Men vs Women

There are several possible explanations for these findings, Dr. Roberts said. First, there may be sex differences in the prevalence of risk factors for MCI in middle age and in the later stages of life. Alternatively, there may be sex differences in the progression of MCI to dementia, she speculated. "If you just look at prevalence, it might appear that MCI is higher in men than women if women are progressing faster from MCI to dementia," she explained. There may also be differences in the rate of mortality among persons with MCI.

They hope to follow these subjects over time to confirm that men indeed develop MCI at a higher rate than women. They have recently applied for funding to continue this project, she said.

The study is supported by grants from the National Institutes of Health and the Robert H. and Clarice Smith and Abigail Van Buren Alzheimer's Disease Research Program.

American Academy of Neurology 60th Annual Meeting: Abstract S21.001. Presented April 16, 2008.

Medscape Medical News © 2008  Medscape

Cite this: Susan Jeffrey. Mild Cognitive Impairment More Common in Men Than in Women - Medscape - May 01, 2008.