Nearly one million Canadians live with psoriasis. Characterized by red, scaly patches on the skin, psoriasis is often itchy, painful and can lead to low self-esteem. People with psoriasis are at an increased risk for many major medical disorders, including psoriatic arthritis, an inflammation of the joints that can lead to irreversible joint damage. Between 10 to 30 per cent of patients with psoriasis develop psoriatic arthritis.
For years, the rheumatology and dermatology communities have been trying to understand why some patients with psoriasis go on to develop psoriatic arthritis. A team of University of Calgary researchers believe they have found a link.
The link between depression and psoriatic arthritis
A multidisciplinary team, led by senior investigator Dr. Cheryl Barnabe, a member of the McCaig Institute for Bone and Joint Health and the O’Brien Institute for Public Health in the Cumming School of Medicine’s departments of Medicine and Community Health Sciences has found that psoriasis patients who developed depression were at a 37-per-cent greater risk of subsequently developing psoriatic arthritis, compared with psoriasis patients who did not develop depression. Their findings were published in the Journal of Investigative Dermatology.
Because of the highly visible nature of psoriasis, people with the condition often experience social isolation and depression. Based on recent laboratory work demonstrating that major depressive disorder is associated with increased systemic inflammation, the team of researchers hypothesized that psoriasis patients who develop depression are at increased risk of subsequently developing psoriatic arthritis.
Database with more than 70,000 patients analyzed
Investigators used a primary care medical records database in the United Kingdom to identify over 70,000 patients with a new diagnosis of psoriasis. Through followup records, they identified individuals who subsequently developed depression and those who developed psoriatic arthritis. Patients were followed for up to 25 years or until they developed psoriatic arthritis.
Statistical analysis showed that patients with psoriasis who developed major depressive disorder were at 37-per-cent greater risk of subsequently developing psoriatic arthritis compared with patients who did not develop depression, even after accounting for numerous other factors such as age, body mass, other illnesses and use of alcohol.
First author Ryan Lewinson, PhD graduate of the Biomedical Engineering Program in the Schulich School of Engineering and a MD-PhD Leaders in Medicine student, points out that more work is needed to identify the role of both depression and systemic inflammation, which is elevated in depression, in psoriatic arthritis. "Future studies will need to focus on the mechanisms involved in the relationship between psoriasis, depression and development of arthritis," he says.
Prevention is key
The study highlights the need for heightened prevention, detection and management of depression in psoriasis patients. According to Barnabe, it’s important to get the study findings out to physicians who treat psoriasis patients. “Addressing depression in patients with psoriasis might keep them from developing psoriatic arthritis, preventing the need for long-term immunosuppression and damage to bones, joints and tendons before it occurs.”