Psoriasis is caused by dysregulated interactions of the innate and adaptive immune system in skin epithelium and connective tissue, including the activation and proliferation of T helper cells. As an autoimmune disorder causing widespread inflammation, it is unsurprising that psoriasis is associated with a number of non-dermatological conditions. Continued psoriasis research may give insight into the etiology and management of these diseases.
Common psoriasis comorbidities include:
1. Arthritis
The most well-known non-dermatological symptom, up to 40 percent of psoriasis patients also deal with psoriatic arthritis. This joint pain is generally experienced by those with more severe disease. These patients typically experience synchronous flares and remission of skin and joint symptoms.
2. Metabolic Syndrome
Metabolic syndrome is a cluster of physical conditions that include increased blood pressure, high blood sugar, excess abdominal fat, abnormal cholesterol levels and/or high triglycerides. Each of these independently increases the risk of heart disease, stroke, and diabetes, but are generally found together as metabolic syndrome. As many as 40 percent of patients with psoriasis experience metabolic syndrome, compared to 23 percent of the general population.
3. Cardiovascular Disease
In addition to being more likely to develop its risk factors, patients with psoriasis also experience higher rates of cardiovascular disease. Those with severe psoriasis are 58 percent more likely to have a major cardiac event and 43 percent more likely to have a stroke. As further research illuminates the link between inflammation and heart disease, new insights into treating both may significantly benefit psoriasis patients.
4. Diabetes
With higher-than-average blood sugar, patients who have severe psoriasis are also 30 percent more likely to develop type 2 diabetes. This may be due to a combination of factors, from inflammatory processes to a more sedentary lifestyle caused by associated joint pain.
5. Inflammatory Bowel Disease
Another group of chronic inflammatory conditions, inflammatory bowel disease in some form develops in 10 percent of women with psoriasis. Incidences of Crohn’s disease and ulcerative colitis are 3.8 to 7.5 times greater among psoriasis patients than in the general population.
6. Uveitis
Roughly 7 percent of patients with psoriatic arthritis also develop uveitis, a severe form of eye inflammation that is often painful and may lead to vision loss. This manifestation develops more frequently in patients with pustular psoriasis.
7. Depression
Psoriasis is rarely life-threatening, but it can be a serious detriment to a person’s quality of life. Depression prevalence among psoriasis patients may be as high as 19 percent, compared to 6.7 percent in the U.S. general population. There is also a generally positive association between depressive symptoms and the length and severity of the disease. With as many as 60 percent of patients indicating stress as a psoriasis trigger, many fall into a negative feedback loop of worsening symptoms and mounting stress.
All of these associated conditions must be taken into consideration when designing and conducting psoriasis clinical trials, especially when establishing eligibility criteria.