Meanwhile, the other study looked at data on nearly "1,000 people with an average age of 79 who had been enrolled into a large US heart study," the UK's Press Association (7/6) reports. "At the beginning, all were free of dementia." Psychological tests "identified 125, or 13%, of the study participants, [who] were classified as being depressed." By study end, some 17 years later, "164 of the recruits had dementia, of whom 136 were diagnosed with Alzheimer's."

Among those with "dementia, 22 percent had been depressed at the study's start, compared to 17 percent who were not depressed," the Boston Globe (7/5, Cooney) "White Coat Notes" blog reported. "Looking at how people scored on the 60-point depression screening test, the researchers found that for each 10-point increase, there was a 50 percent increased risk of dementia." And "after accounting for age, sex, and other characteristics among the participants, depressed people were more than one and a half times more likely to develop dementia than people who were not depressed."

Putting forth theories about why the link may exist, investigators say that "depression could be an early sign of changes in the brain that lead to dementia," CNN (7/5, Landau) reported. "Exercise and social engagement have been shown to protect against dementia in other research." And, says the lead author of the Massachusetts study, "given that depressed people tend to be less active and more withdrawn, these habits could influence the development of dementia."

Related Links:

- Depression may double dementia risk, say researchers," BBC News, July 6, 2010.

- Depression may increase risk of dementia, study says," Boston Globe, July 12, 2010.