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Having Psoriasis and Depression May Lead to Psoriatic Arthritis

February 28, 2017
Patients who have psoriasis, and then are diagnosed with major depressive disorder, appear at increased risk for developing psoriatic arthritis; the common link may be increased systemic inflammation.

Interview with Cheryl Barnabe, MD

Of the estimated 7.5 million people who have been diagnosed with psoriasis in the United States, nearly 40% will develop psoriatic arthritis (PsA),1  according to the American Academy of Dermatology. However, there has been little to explain the mechanisms driving these conditions.

To address these questions, a team of researchers from Cumming School of Medicine in Calgary, Canada, followed 73,447 patients for 25 years in The Health Improvement Network—a primary care medical records database in the UK. They found that patients who had psoriasis and also received a diagnosis of major depressive disorder (MDD) were as much as 37% more likely to develop PsA.2

The research, published in the Journal of Investigative Dermatology,2 is among the first studies offer clinicians better insight into the way depression affects the body and how it may be linked to psoriatic arthritis, according to Cheryl Barnabe, MD, an associate professor of medicine and community health sciences at the University of Calgary in Alberta, Canada, and an author of the study.

Patients who have psoriasis and develop depression are at risk for psoriatic arthritis, too.

“This study draws into question the biologic mechanisms by which depression increases the risk of developing psoriatic arthritis,” Dr. Barnabe told Practical Pain Management. “These mechanisms may include altered systemic inflammation as a consequence of depression, or even the role of lifestyle behaviors, such as physical activity or nutrition, which are typically negatively impacted by depression, and which may place an individual at risk for psoriatic arthritis.”

For years, researchers have been exploring the connection between psoriasis, depression, and PsA.3 Because psoriasis and PsA share certain genetic and inflammatory associations,4,5 an investigation of patients with MDD showed a consistency in signs of elevated inflammatory markers in the blood, possibly linked to the pathophysiology of MDD.6 Given these insights, Dr. Barnabe and her colleagues sought to determine if having MDD predisposed psoriasis patients to PsA.

“As we planned this study, we were guided by the hypothesis that depression was an intermediary between psoriasis and psoriatic arthritis,” in such a way that a critical level of inflammation could push the phenotype from skin disease alone to a systemic condition also affecting joints, tendons, and enthuses, she said.

Depression Links Psoriasis and Psoriatic Arthritis

From The Health Improvement Network data, comprising about 5% of the United Kingdom’s population, the researchers found a consistent pattern in which patients who had psoriasis and also received a diagnosis of MDD were at significantly higher risk of developing PsA compared to psoriasis patients who were not diagnosed with MDD, (unadjusted hazard ratio [HR] 1.56, 95% confidence interval [CI] 1.28-1.90, P < 0.0001).2

Even with the most conservative analysis, including all forms of possible confounders (age, sex, obesity, smoking, alcohol, psoriasis severity, etc), the risk remained significant for psoriasis patients with MDD (HR 1.37, 95% CI 1.05-1.80, P = 0.021).2

According to Dr. Barnabe, while the data cannot prove causation, especially since there was no way to measure systemic inflammation directly from the patients, there was a possibility that some patients already being treated with systemic therapies for their moderate-to-severe psoriasis may have been more protected from developing PsA.

Regardless, the study findings were sufficient to raise attention to the prospect that depression may be a significant clinical indicator for PsA risk, something that doctors may want to consider.

Clinical Impact of Systemic Inflammation on Patients

“Although I am not a primary care provider or a dermatologist, I would suspect that physicians would not be routinely screening for depression in patients with psoriasis,” Dr. Barnabe said. “Physicians managing patients with psoriasis must make efforts to identify and address depression, as this comorbidity may have a downstream impact on reducing the transition to psoriatic arthritis.”

Ideally, this would include rapid, effective management of psoriasis symptoms, but also incorporating psychosocial management of the cosmetic burdens associated with having psoriasis, she explained.

As for future research, Dr. Barnabe believes there many possibilities for the relationship between systemic inflammation, depression, and numerous autoimmune diseases.

Dr. Barnabe currently is serving as part of a grant team, assessing possible inflammatory changes in the brains of patients with inflammatory arthritis and how those patients may respond to treatment.

The study authors were supported in part by studentships through the Canadian Association of Psoriasis Patients and Alberta Innovates Health Solutions. Dr. Barnabe is a Canadian Institutes for Health Research New Investigator in Community-Based Primary Healthcare. The authors declared no conflicts of interest.

Last updated on: March 2, 2017
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New Research Into Psoriatic Arthritis
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