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Older Women who are Depressed Have Twice the Risk for Developing Mild Cognitive Impairment and Dementia Later in Life

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Researchers who studied 6,376 older women for several years learned that those who were depressed at the beginning of the study were more likely to develop mild cognitive impairment or dementia later on than women who weren’t depressed.

New Research in the Journal of the American Geriatrics Society

The researchers set out to learn whether older women who have depression are at higher risk for developing mild cognitive impairment or dementia. The researchers were from the Department of Psychiatry and Behavioral Medicine and the Department of Population Health at the Medical College of Wisconsin in Milwaukee, WI; the Department of Biostatistical Sciences at Wake Forest University Medical Center in Winston-Salem, NC; Family and Child Nursing, University of Washington in Seattle, WA; and the Department of Epidemiology and Population Health, at Albert Einstein College of Medicine, New York, NY.

The researchers noted that up to 16% of people aged 70 to 89 have Mild Cognitive Impairment, or MCI, which is a condition marked by forgetfulness—more than what is considered normal for people of that age. People with MCI also experience difficulties with language, attention, reasoning and judgment, as well as subtle changes in day-to-day functioning. About 10 to 15% of people diagnosed with MCI will eventually develop Alzheimer’s disease, said the researchers. They noted that unless effective prevention and/or treatments are discovered, some 8.5 to 13 million Americans will develop Alzheimer’s disease by the year 2050.

Participants in this study were post-menopausal women aged 65 to 79 years old. The women were tested at the beginning of the study for depression symptoms. The women were also asked to report details about their health, including their weight and levels of physical activity. At the beginning of the study, and again every year, women were given several tests to measure their cognitive function. Women who scored lower on the cognitive function tests were given additional mental status tests and were also examined by physicians experienced in diagnosing dementia.

At the start of the study, 508 of the women had significant depressive symptoms. The study revealed that the women who were depressed had about twice the risk for developing mild cognitive impairment and probable dementia as women who weren’t depressed.

The researchers noted that several other studies have also shown a link between depressive symptoms and MCI—although, as they pointed out, their study contained the largest group of older women in which that link was examined.

Why Depression May Lead to MCI or Alzheimer’s Disease

Although no one knows for sure why depressed women are more likely to develop MCI or Alzheimer’s disease, the researchers examined some theories. Though heart disease and related problems, like high blood pressure, have been mentioned as possible causes, the researchers said that hasn’t been proven by their study or by other recent studies. They did suggest, however, that the stress hormones which are released when you’re depressed could lead to damage in areas of the brain. Another possibility is that depression could be an early sign of dementia or cognitive decline.

What Should I Do?

If you think you might be depressed, talk it over with your health care practitioner. He or she can tell you whether you should be treated for depression. According to the researchers, adequate treatment for depression may help reduce your risk of developing dementia later on.

This summary is from the full report titled "Depressive Symptoms and Incidence of Mild Cognitive Impairment and Probable Dementia in Elderly Women: The Women’s Health Initiative Study." It is in the January 2011 issue of the Journal of the American Geriatrics Society. The report is authored by Joseph S. Goveas, MD; Mark A. Espeland, PhD; Nancy F. Woods, PhD; Sylvia Wassertheil-Smoller, PhD, and Jane M. Kotchen, MD, MPH.