Swedish researchers found that women who were obese throughout their adult lives were more likely to lose brain tissue, a condition known as brain atrophy that has been linked to impaired brain function and dementia.

The study didn't answer the question of how obesity might lead to loss of brain tissue. But researchers say obesity increases the risk of diabetes and high blood pressure, both of which can cause damage that may lead to brain atrophy.

Researchers say the study shows that obesity may be a risk factor for dementia in women.

In the study, researchers followed a group of 290 women who were born between 1908 and 1922. All of the women had four follow-up exams between 1968 and 1992.

At the last exam, when the women were aged 70 to 84, they had a computed tomography (CT) scan to measure for any brain atrophy.

Researchers compared the results of the CT scan to the women's body mass index (BMI, a measure of weight in relation to height) and found that being overweight or obese increased the risk of brain loss in the region of the brain known as the temporal lobe, which plays an important role in language, memory, and hearing.

A BMI between 25 and 30 is considered overweight and a BMI over 30 is considered obese.

The study showed that women with brain atrophy had, on average, a BMI that was 1.1 to 1.5 points higher than women without brain atrophy. Overall, the women's BMI increased during the 24-year study period, but the increase was greater among those with evidence of brain tissue loss. In addition, researchers found the risk of brain atrophy increased 13% to 16% per each increase in the women's BMI.

Source: Diabetes In Control.com: Gustafson, D. Neurology, Nov. 23, 2004; vol 63: pp 1876-1881.