Nearly one in every 30 people has itchy red patches on the skin, patches with unsightly scales. They have dry and cracked skin, so much so that it sometimes starts bleeding. These are symptoms of the skin disease psoriasis, which can also affect the fingernails and toenails, and even cause swollen and painful joints. It’s unsightly, it’s distracting, and it can even get to the point of interfering in everyday activities.
At least 40 percent of people with psoriasis have a family member with the condition, pointing to a genetic link. It is believed to be an autoimmune condition, and many autoimmune illnesses run in families. Infections, stress, and smoking are all believed to trigger outbreaks, as can sunburn or other injury to the skin. However, psoriasis is only triggered in people who already have the underlying condition. The symptoms generally begin to appear around late adolescence or before.
Another risk factor is being overweight or obese. In one study, 78 percent of psoriasis patients had been obese prior to developing the condition. Overall, nearly twice as many children with psoriasis were overweight or obese than children without. That suggests that being overweight can be a cause or an effect of psoriasis. People with psoriasis have nearly twice the risk of diabetes—a condition itself associated with obesity—as the general population, and researchers think these are likely to be related. In particular, people who are prone to psoriasis may also be more likely to become overweight and more vulnerable to a condition called insulin resistance, which is a precursor to diabetes.
Symptoms of psoriasis can be treated with skin cream and aloe, and there is some evidence that omega-3 fatty acids are effective against the inflammation. Some topical remedies are available by prescription, such as corticosteroids and synthetic vitamin D, or over-the-counter, such as aspirin and coal tar. Testing is being done on a synthetic form of a molecule called DHA that is expected to be more effectively absorbed by the skin. Various kinds of light therapy are also available. A variety of oral medications are also sometimes used, including methotrexate and retinoids.