Can Depression Up Odds for Arthritis Linked to Psoriasis?

Mood disorder may increase inflammation throughout the body.

Depression in people with the chronic inflammatory skin disease psoriasis increases the risk of getting the joint condition known as psoriatic arthritis by about 37 percent, new research indicates.

The finding raises concerns because depression is not uncommon in people with psoriasis, according to the authors of the study in the Feb. 22 issue of the Journal of Investigative Dermatology.

"For many years, the rheumatology and dermatology communities have been trying to understand which patients with psoriasis go on to develop psoriatic arthritis, and how we might detect it earlier in the disease course," senior investigator Dr. Cheryl Barnabe said in a journal news release. She is from the McCaig Institute for Bone and Joint Health and the O'Brien Institute for Public Health at the University of Calgary in Alberta.

While the study found a connection between depression and the development of psoriatic arthritis, it wasn't designed to prove a cause-and-effect relationship.

Psoriasis is a condition characterized by red, itchy and scaly skin patches. These patches can sometimes be disfiguring. Psoriatic arthritis generally occurs in people with psoriasis, though it can occur on its own, according to the American College of Rheumatology. The condition causes joint pain and swelling, typically in the large joints and fingers and toes. It can cause joint damage, too.

The study authors noted that prior work has linked having a major depressive disorder with a high risk for systemic inflammation. This could explain why depression would bump up the risk for psoriatic arthritis.

To explore the link, the investigators analyzed information on more than 70,000 psoriasis patients in the United Kingdom that had been collected by a primary care database.

Patients were tracked for upwards of 25 years.

The researchers adjusted the data to account for other factors, such as age and drinking habits. Ultimately, they determined that people who had been depressed faced a much higher risk for psoriatic arthritis than those who hadn't been depressed.

"There is a tendency to think of depression as a purely 'psychological' or 'emotional' issue, but it also has physical effects and changes in inflammatory and immune markers have been reported in depressed people," said Dr. Scott Patten, from the O'Brien Institute.

"Depression may be a risk factor for a variety of chronic conditions, and this research is an example of how big data approaches can identify these associations," he said.

By Alan Mozes, HealthDay News