Can Antidepressants Prevent Psoriasis in Depressed Patients?
A study of over 67,000 depressed patients tracks new psoriasis diagnosis to determine whether antidepressants protect against this common autoimmune disease.
Psoriasis is a chronic autoimmune disease causing body-wide inflammation. The most familiar and visible symptoms of psoriasis affect the skin due to accelerated growth of skin cells, leading to red plaques, scaly, flaky skin, pitting of fingernails, and related changes. Psoriasis also affects joints, causing a potentially severe form of arthritis in 10 to 20 percent of affected people and leading to significant pain and infirmity.
Over 3 percent of people in the US (2014) have psoriasis, and an estimated 125 million are affected world-wide. Psoriasis is not just a skin and joint disease, however. People with psoriasis are more likely to develop other medical conditions, including type II diabetes, cardiovascular disease, high blood pressure, and other autoimmune diseases.
The psychodermatology of psoriasis
Psoriasis and psychiatric conditions are interrelated. This risk of depression is significantly higher for people with psoriasis, especially those treated with strong medications (“biologicals”). Likewise, the risk of psoriasis is significantly higher in people who are depressed (2019). Depression often makes it harder to take care of oneself, limiting the effectiveness of psoriasis treatment. Psoriasis is known to “flare-up” when stress is high (2013), and can be worsened by factors including tobacco and alcohol use, cold weather and infections.
For many, psoriasis contributes to depression and anxiety and visa versa. This is due to biological factors, notably inflammation and differences in cytokine activity (pro-inflammatory chemicals familiar recently as the “cytokine storm” in severe Covid-19), as well as because of social and psychological influences. Psoriasis contributes to social anxiety, affecting self-image and stigmatization via feelings about physical appearance and impact on body image (2017).
Depression includes feelings of worthlessness, helplessness, hopelessness, self-blame, and social withdrawal, enforcing negative beliefs about appearance and increasing stigma. In addition to anxiety and depression, psoriasis is also associated with increased suicidal thinking (2011). The need to treat psychiatric and autoimmune aspects together is critically important.
To that end, there is an increasing body of research in psychodermatology to uncover overlapping factors and help refine treatment approaches. While smaller studies have suggested antidepressants might worsen psoriasis, none have followed a large group before psoriasis was diagnosed. Because psoriasis can be triggered by stress and related factors, smaller studies may have identified a correlation between medication and psoriasis, giving a false appearance of causality, as the same factors which trigger psoriasis flare-ups also increase the likelihood of antidepressant prescription.
Can antidepressants protect against psoriasis?
A recent study in the Journal of Affective Disorders (2020) used a prospective design, following a group of depressed patients over time before any were diagnosed with psoriasis to see whether treatment made a difference in psoriasis rate. Looking at over 67,000 patients with Major Depressive Disorder (MDD) in the the Taiwan National Health Insurance (NHI) program, researchers tracked who did and did not develop psoriasis over the course of 9 years as a function of antidepressant use and related factors (age, dose of medication, type of medication, gender, etc.)
Overall, they found that the risk of psoriasis developing in patients with MDD was significantly lower for patients taking medication. They found that antidepressants appeared to have a protective effect against psoriasis in people with depression, with a hazard ratio of 0.70 for depressed patients receiving antidepressants. This was true for different classes (e.g. Selective Serotonin Reuptake Inhibitors SSRIs, tricyclics) and dosage levels. The apparent protective effects of antidepressants was enhanced in women and nonelderly adults.
The study authors highlight that antidepressants have been shown to modulate inflammation, an effect which could alleviate psychiatric as well as autoimmune problems. For example, they report data showing that SSRIs reduce levels of key inflammatory molecules in the body, including IL-6, IL-1β, TNF-α, and IL-10.
This study is important because they followed a large number of patients over time, controlling for many variables to prospectively track antidepressant use with the future development of psoriasis. For at-risk patients, such as those with a strong family history, antidepressants may be useful for preventing the development of psoriasis and its many associated problems. However, ongoing research is needed to further clarify the impact of antidepressant medications on the immune system to determine if any protective effect is replicated in future research, and whether any particular medications are better at prevention, or even exacerbate or cause psoriasis.
It is important for primary care clinicians, psychiatrists, and dermatologists to be aware of the above relationships so they can screen and treat accordingly. For people concerned about psychiatric issues and psoriasis, it is important to integrate all the relevant factors, informing different specialists of the need for a coherent treatment approach to ensure coordination of care.
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