Obesity-psoriasis link questioned

Obesity does not seem to trigger psoriasis, a troublesome skin condition that affects 4.5 million American adults. But people with psoriasis are more apt to become overweight, according to University of Utah research.

Because obesity rates among patients with psoriasis are twice that of the general population, researchers who were studying patients at the U. dermatology clinics thought they'd see a causative link, said Dr. Gerald G. Krueger, professor of dermatology and Cummings Presidential Endowed Chair in Dermatology.

The findings, published this week in the Archives of Dermatology, were the opposite of what they expected.

Instead, they're left to wonder if it's poor self-image resulting from psoriasis that leads to the weight gain, he said. Researchers speculate that people who are self-conscious about the disease are less apt to be active and socialize, so they gain weight. It's also possible, they say, that the link might be caused by psoriasis turning on an obesity gene in people with the disease, said Krueger, who is corresponding author on the study.

About 2.5 percent of Utahns have psoriasis, which typically causes lesions on the skin that are inflamed and covered by scaly patches of skin. About 60 percent of cases are inherited, and researchers have identified a region on chromosome 6 that seems to confer the risk. A release that announced the findings said that someone with a family history of psoriasis has about a 1 in 5 chance of getting the disease and those who do usually develop it earlier in life than those who have no family history.

There also appears to to be a link between smoking, obesity and psoriasis among those patients who do not have the earlier, familial form of psoriasis, they found. The obese patients with psoriasis they studied were four times more likely to smoke than obese people in the general population. And smoking seems to worsen symptoms, Krueger said.

The study found 25 percent of patients smoked cigarettes, compared to the general population's 13 percent. Smokers are three to six times more likely to develop psoriasis than nonsmokers. The study also found that 34 percent of the obese people in the study smoked, compared to 9 percent of obese people in the general population.

They studied 557 patients enrolled in the Utah Psoriasis Initiative, a project that takes detailed information from those with psoriasis and looks for any things they have in common, including symptoms, lifestyle and personal traits. The goal is to learn what causes the disease. Currently 750 patients are enrolled in the initiative, but some of them joined after data had already been culled for the obesity and smoking research.