Dermatology and mental health: Study links psoriasis to OCD

In an ongoing effort to better understand possible links between skin conditions and mental health, researchers at Yale School of Medicine have discovered an association between psoriasis and obsessive-compulsive disorder (OCD) that may have important implications for dermatology practice.

Their study, published in Archives of Dermatological Research on May 25, uses data from the All of Us Research Program, an NIH initiative that collects health information from patients across the United States.

This health data is currently being used for thousands of research projects investigating a variety of health conditions, and at Yale, researchers used the surveys and electronic health records of over 250,000 diverse participants to demonstrate for the first time an association between OCD and psoriasis in U.S. adults.

Psoriasis is an immune-mediated inflammatory skin condition characterized by scaly plaques on the body. It affects more than 8 million people in the U.S. OCD, a psychiatric disorder characterized by obsessive thoughts and compulsions, may affect between 2 and 3 million people. Among the participants analyzed in the study, researchers found that those with psoriasis had a 1.5-fold increase in odds for an OCD diagnosis.

"We're interested in the overlap between psychiatric disease and inflammatory skin disease," says Jeffrey Cohen, MD, assistant professor of dermatology and principal investigator of the study. "There may be opportunities for dermatologists to identify the potential for mental health disorders in one of our patients that would then allow us to appropriately refer that person to a mental health professional."

Symptoms, inflammation, and genetics

There are a few potential explanations for the OCD-psoriasis link that Cohen and his team found. It's possible that symptoms associated with psoriasis—chronic itching, sleep troubles, disfigurement—might put patients at greater risk for developing OCD. But it's also possible that certain OCD-related tendencies, such as too much bathing or handwashing, could exacerbate psoriasis.

"Excessive bathing can dry the skin and flare psoriasis. The itch of psoriasis can lead to a lot of scratching that can become a compulsion," says Cohen.

Inflammation could also play a role. Both OCD and psoriasis are associated with elevated levels of inflammatory cytokines, such as IL-2, IL-6, and TNF-α, that play a role in the body's immune response. Cohen believes this could be significant, especially considering genetic evidence that shows family members of people who have OCD have higher rates of immune-mediated disease, such as skin conditions that include psoriasis.

A diverse dataset

Though the same OCD-psoriasis association had previously been found in Taiwanese and Swedish populations, this study was the first to demonstrate the link in American adults, and in particular, those Americans who are often left out of biomedical research.

The All of Us database that Cohen and his team used collects health information from U.S. patients of various races, ethnicities, ages, gender identities, sexualities, and other classifications. This provides researchers such as Cohen access to a highly valuable and largely underrepresented data pool.

"It remains a really great database to use for this because it has information about a lot of people from diverse groups across the United States, and the data that's there is quite powerful," says Cohen.

Integrating mental health and dermatology

Cohen has been using All of Us data since 2021 to discover a number of other associations, such as eczema and eating disorders, and atopic dermatitis and OCD. His findings add to the growing body of research linking the skin with the mind, but despite such evidence, mental health is frequently not considered in dermatology practice. Cohen believes this is an area where the field could improve.

"In dermatology, we're not that great at asking about certain mental health disorders that may be relevant," says Cohen. "But if we identify it, if we see that someone might be at risk, we could put the wheels in motion to try to get them thoroughly evaluated and, if needed, treated for whatever it is that's going on, in addition to what we're doing for their skin."

As medical professionals who often have frequent contact with their patients, dermatologists are well positioned to identify the potential for mental health concerns early on, Cohen says. Thus, increasing the awareness around research findings that link the skin and the mind will be key for dermatologists and their patients alike.