ROCHESTER, MINN. -- A new, six-year study of people age 40 to 70 years old has found that people with diabetes and high blood pressure are more likely to experience cognitive decline (a decline in mental ability) as compared to people of that age who do not have the conditions. The study results are leading researchers to believe that controlling hypertension and diabetes that begin before age 60 might lessen the burden of cognitive impairment later in life.
The study is published in the Jan. 9, 2001 issue of Neurology, the journal of the American Academy of Neurology.
"While the participants in the study may not have noticed any decline in their mental ability, the decline was statistically significant," says David Knopman, M.D., a Mayo Clinic neurologist and the senior author of the study. "The results point to the fact that there are things some people may be able to do during middle age to help preserve our mental abilities later in life."
Dr. Knopman conducted the study while at the University of Minnesota. He is currently a neurologist at Mayo Clinic in Rochester, Minn.
"We aren't sure at this point exactly how diabetes and high blood pressure affect cognitive function," says Dr. Knopman. "Additional research will be needed to determine the exact mechanisms."
The Atherosclerosis Risk in Communities (ARIC) study was initiated in 1987 as a multiethnic, multicenter study of vascular disease in Forsyth County, N.C.; Jackson, Miss.; suburban Minneapolis, Minn.; and Washington County, Md. The study is funded by the National Institutes on Health.
The study enrolled over 10,000 people who underwent cognitive testing at the beginning of the study; those beginning scores were compared with scores from tests taken six years later.
The study also compared the results between two age groups: those under age 58 and those age 58 and older. Diabetes was associated with greater cognitive decline in both age groups when participants who have diabetes were compared to participants without the disease. High blood pressure, however, was found to be associated with greater cognitive decline in only the age 58 and older group of participants. The ARIC study, which enrolled a substantial number of African Americans, found no substantial racial differences in risks for cognitive decline.
The study found no association between cognitive decline and smoking, high cholesterol or use of non-steriodal anti-inflammatory medications such as ibuprofen.