Older people who are depressed are much more likely to develop a dangerous type of internal body fat -- the kind that can lead to diabetes and heart disease -- than people who aren't depressed, a disturbing new study found.

The connection goes beyond obesity and suggests some biological link between a person's mental state and fat that collects around the internal organs, scientists said.

"For the depressed public, it should be another reason to take one's symptoms seriously and look for treatment," said study co-author Stephen Kritchevsky, director of the Sticht Center on Aging at Wake Forest University in Winston-Salem, N.C.

People with depression were twice as likely as others to gain visceral fat -- the kind that surrounds internal organs and often shows up as belly fat. It raises the risk for heart disease and diabetes.

Previous research has linked depression with those same health problems.

Some researchers believe depression triggers high levels of the stress hormone cortisol, which promotes visceral fat. The cortisol connection may explain the findings, Dr. Kritchevsky said.

The research, published in Monday's Archives of General Psychiatry, is the first large study to track people over time to see if those with depression were more likely to gain weight. Mostly federally funded, the study used data from 2,088 people in the ongoing Health, Aging and Body Composition study. That project is following healthy older Americans to find out how changes in bone, fat and lean body mass affect health.

The participants, all in their 70s, were recruited in and around Memphis, Tenn., and Pittsburgh in 1997 and 1998 and were followed for five years.

Researchers screened for symptoms of depression at the start of the study and again at four follow-up visits.

They measured visceral fat with CT scans. They calculated body mass index, body fat percentage, waist size and the distance between the back and the biggest part of the belly.

There were 84 people with depression symptoms at the start of the study. They gained, on average, 9 square centimeters of visceral fat. In contrast, the 2,004 people who weren't depressed lost visceral fat -- on average, 7 square centimeters.

That variation "could mean the difference between developing a cardiovascular disease or not," said lead author Nicole Vogelzangs of VU University Medical Center in Amsterdam, the Netherlands, in an email.

Both groups, depressed and nondepressed, were overweight on average at the start of the study, with approximately the same average body mass index.

When the researchers took into account other risk factors for obesity, including the depressed group's higher visceral fat levels in the beginning, they still found a connection between depression and visceral fat gain.

They also found a similar link to visceral fat gain in people with recurring depression over the years. Adjusting for antidepressant use didn't change the findings either.

Researchers didn't make adjustments for poor eating habits, but they found no link between depression and BMI or body fat percentage.

"Since such an increase in overall obesity was not clearly found, we believe a biological explanation is more likely" than poor diet, Dr. Vogelzangs said.

The researchers did find hints of a depression link with waist circumference and the back-to-belly measurement -- two other gauges of visceral fat.

That suggests depression has a specific tie with fat gained around the organs in the abdomen. The good news is visceral fat is easier to lose than subcutaneous fat, Dr. Kritchevsky said.

David Baron of Philadelphia's Temple University School of Medicine praised the study, although he wanted to know more about the participants' family history of obesity. The connection between brain and body makes sense, he said.

"Depression is a physical illness," Dr. Baron said. "Maybe we should be even more aggressive in treating depression in this age group, whether through medication or talk therapy."