Increasing fruit and vegetable consumption could help reduce new cases of dementia, researchers say. (CBC)

Preventing Type 2 diabetes and depression could help reduce rates of dementia, a new study concludes.

Researchers don't know what causes dementia, but factors such as heart disease, a history of depression, diet and education level are known to play a role.

In Friday's issue of BMJ, researchers from France and the U.K. estimated which public health interventions might work best for warding off future dementia, assuming no effective treatment is found.

The first analysis looked at 1,433 healthy people over the age of 65 living in the south of France, who were recruited for the study between 1999 and 2001.

Participants gave information about their medical history and measures such as height, weight, education level, monthly income, mobility, dietary habits, alcohol consumption, and tobacco use, and did a reading test as measure of intelligence.

Study participants were tested for signs of dementia after two, four and seven years.

'Effective prevention of diabetes, depression and heart disease could potentially improve the lives of millions of people affected by this cruel condition.'— UK Alzheimer's Society

Eliminating depression and diabetes and increasing fruit and vegetable consumption would lead to an overall 21 per cent reduction in new cases of dementia, the researchers estimated.

Increasing education would lead to an estimated 18 per cent reduction in new cases of dementia across the general population over the next seven years, the French team said.

In comparison, eliminating the main genetic risk factor known to be associated with dementia would lead to a seven per cent reduction.

Earlier detection

"Diabetes, and perhaps also depression, should be the principal targets of future population based health prevention programs," the study concluded. It called for more research on younger adults to test the idea.

The U.K. Alzheimer's Society agreed.

"Effective prevention of diabetes, depression and heart disease could potentially improve the lives of millions of people affected by this cruel condition and reduce the billions spent on dementia care each year," the group said in a statement on its website commenting on the research.

A second study appearing in the same issue looked at the health records of more than 135,000 people in the U.K. aged 60 or over.

Death rates were more than three times higher in people with dementia than in those without dementia in the first year after diagnosis, study leader Greta Rait from the U.K. Medical Research Council and her colleagues said.

The British researchers concluded earlier and better detection of dementia by general practitioners is needed.

Developing better education and training for primary care physicians to detect dementia early is a key area, Elizabeth England, a clinical research fellow at the University of Birmingham, said in a journal editorial accompanying the studies.

The French study was funded by an unconditional grant from Novartis and the National Research Agency. The U.K. study was funded by the North Central London Research Consortium.