Tuesday, September 7, 2010
Mild cognitive impairment more common in older men than older women
NIH-supported study suggests gender differences in cognition problems
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 today in Neurology.
Primarily funded by the National Institute on Aging (NIA), part of the National Institutes of Health, 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 percent 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 it was consistently higher in men than women across all age ranges.
Ronald C. Petersen, Ph.D., M.D., and his team at the Mayo Clinic, Rochester, Minn., conducted the research, which was also supported by the National Institute of Mental Health (NIMH), also part of the NIH. Additional funding was provided by the Robert H. and Clarice Smith and Abigail van Buren Alzheimer's Disease Research Program and the Rochester Epidemiology Project, also supported by NIA.
"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," said NIA Director Richard J. Hodes, M.D. "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 non-amnestic MCI, where different cognitive problems arise, such as with language.
Results of the study indicated that:
- Overall, MCI was more prevalent in men (19 percent) than in women (14 percent), even after adjusting for several demographic variables and clinical factors, such as hypertension and coronary artery disease.
- Of the 16 percent 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 percent among participants with less than nine years of education to just 11 percent 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 percent. 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, Petersen said. 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.
The NIA leads the federal government effort conducting and supporting research on the biomedical, social and behavioral issues of older people. For more information on aging-related research and the NIA, go to www.nia.nih.gov. The NIA provides information on age-related cognitive change and neurodegenerative disease specifically at its Alzheimer’s Disease Education and Referral (ADEAR) Center site at www.nia.nih.gov/Alzheimers. To sign up for e-mail alerts about new findings or publications, please visit either website.
The mission of the NIMH is to transform the understanding and treatment of mental illnesses through basic and clinical research, paving the way for prevention, recovery and cure. For more information, visit www.nimh.nih.gov.
About the National Institutes of Health (NIH): NIH, the nation's medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit http://www.nih.gov.
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