A history of anxiety disorders or depression, particularly at a young age, may put women at greater risk of obesity, researchers reported Monday.

In a study that followed 820 men and women from childhood through young adulthood, investigators found that women with a history of either depression or anxiety - or, in many cases, both - tended to gain more weight over time.

When it came to depression, the earlier in life the disorder arose, the greater the weight gain.

For example, a 30-year-old woman whose depression was first recognized at the age of 14 weighed, on average, 10 to 15 pounds more than a similar woman without a history of depression. The weight difference was smaller when depression was diagnosed at the age of 18.

Anxiety disorders were associated with an extra 6 to 12 pounds by adulthood, regardless of the age at diagnosis.

In contrast, depression and anxiety disorders did not seem to affect men’s weight gain, the researchers found.

They report the findings in the March issue of the Archives of Pediatrics & Adolescent Medicine.

Though the weight difference linked to depression and anxiety was “not enormous,” the extra pounds could lead to obesity in some women, said lead study author Sarah E. Anderson, of the Friedman School of Nutrition at Tufts University in Boston.

Therefore, treating these disorders could help prevent obesity in some females, she and her colleagues conclude in the report.

Further research is still needed, they say, to confirm that depression and anxiety are in fact causing the excess weight gain.

But some past studies have already shown that this is possible. For example, there’s evidence, Anderson told Reuters Health, that some people respond to depression by overeating.

And some of the same chemical messengers in the body, such as serotonin, are involved in both mood regulation and appetite, she noted. Depression is marked by lowered serotonin levels, whereas food - particularly carbohydrates - can temporarily boost those levels.

So some depressed individuals may essentially “self-medicate” with food, Anderson explained.

One explanation for the gender difference, according to Anderson, could be the fact that women are more likely than men to have depression symptoms that can contribute to weight gain - including increased appetite and excessive sleeping.

The researchers assessed the study participants four different times between 1983, when they were 9 to 18 years old, and 2003. Anxiety disorders and depression were diagnosed using a standard interview.

At the beginning of the study, 27 percent of the girls had an anxiety disorder, while 4 percent were diagnosed with depression. By the last interview in adulthood, nearly half had ever been diagnosed with anxiety, and one quarter had had depression at some point.

If the current findings are correct, the researchers conclude, treating such women could become an important part of the obesity battle.

SOURCE: Archives of Pediatrics & Adolescent Medicine, March 2006.