"The risk for dementia and vascular dementia is especially high when diabetes mellitus occurs together with severe systolic hypertension or heart disease.

Among 1301 individuals 75 years of age or older who were free of dementia at baseline, 350 developed dementia, including 260 cases of Alzheimer's disease and 49 cases of vascular dementia, over 5584 person-years of follow up (6 years).

According to Cox proportional modeling, diabetes mellitus increased the risk of dementia, particularly vascular dementia, independent of other vascular factors, with hazard ratios of 1.5 and 2.6, respectively. The hazard ratios for dementia and vascular dementia were even higher in patients taking oral antidiabetic agents 1.7 and 3.6, respectively.

Dr. Chengxuan Qiu from the Stockholm Gerontology Research Center and co-authors of the report "failed to a find relevant association between diabetes mellitus and Alzheimer's disease risk."

These findings are similar to those of some earlier studies that failed to link the two diseases (see Reuters Health reports December 3, 1997 and August 8, 1996), but contrast with more recent study findings that have shown a link (see Reuters Health reports March 9, 2004 and December 24, 1999).

In the current study, diabetes mellitus in combination with severe systolic hypertension, defined as a systolic blood pressure of 180 mm Hg or greater, significantly increased the risk of dementia, Alzheimer's disease, and vascular dementia with adjusted hazard ratios of 3.0, 2.6, and 11.3, respectively. Diabetes coupled with heart disease had a synergistic effect on vascular dementia with a hazard ratio of 7.8.