One of the critical features of psoriasis is chronic inflammation, a condition also seen in people with insulin resistance, obesity, cardiovascular diseases and abnormal levels of cholesterol. Evidence is now emerging of a link between psoriasis and these other serious diseases, prompting the American Academy of Dermatology to urge patients with psoriasis, particularly those severely affected, to be more aware and monitor their health very closely for signs of these diseases.

Dr Joel M. Gelfand, assistant professor of dermatology and epidemiology at the University of Pennsylvania Perelman School of Medicine in Philadelphia, gave a presentation about it at the American Academy of Dermatology's 70th Annual Meeting in San Diego last week.

In the United States there are about 7 million people with psoriasis, including about 3 million who have never been diagnosed.

The common, chronic skin condition is thought to be caused by a combination of genes, the immune system, and the environment. It can be localized, for instance only breaking out on the scalp or elbows, or it can be all over the body.

Psoriasis forms as raised, red, scaly plaques that can itch, crack and bleed. The disease is painful and can cause disfigurement and disability. In about 20% of cases, it is so severe that no amount of creams and ointments is enough to control it.

The disease can develop at any age, but usually it starts in the 20s and 30s. Around 40% of people with psoriasis have a family history of the disease.

In around 10% of cases, patients develop arthritis with the skin condition: among those with extensive, severe skin disease, incidence of arthritis can be three or four times more common. In most instances, the skin condition appears before the arthritis.

Gelfand told the meeting that studies using new techniques that examine the different types of cholesterol and what they do, suggest people with psoriasis have something in common with people with diabetes: their LDL or "bad" cholesterol particles are smaller and denser. Such particles are more likely to cause arteries to become stiff, increasing the risk of heart attack.

And more recently, there is evidence that HDL or "good" cholesterol is impaired in psoriasis patients: their HDL can't get rid of cholesterol from cells in the artery walls so easily.

Gelfand also cited other research, involving more than 4,000 people with psoriasis, that showed those whose psoriasis covered a greater surface area of skin were more likely to have metabolic syndrome, a group of medical disorders such as obesity, increased triglycerides, blood pressure, and levels of blood glucose, that together raise the risk of developing cardiovascular disease and diabetes.

He said this study found a dose-response effect between psoriasis and metabolic syndrome: the more severe the skin disease, the stronger the link.

Gelfand said some studies have tied severe psoriasis to increase in major cardiovascular events, such as heart attacks.

One study found that people with the severe form of the skin disease may die about five years younger than people without the disease and that at least 50% of this effect is due to cardiovascular disease.

Gelfand's advice to psoriasis patients seeking to reduce their risk of developing these serious diseases is:
  • Don't smoke.
  • Limit alcohol.
  • Eat a healthy, balanced diet.
  • Keep to a healthy weight.
  • Have an active lifestyle.
  • Reduce stress.
  • Have regular checks for blood pressure, blood sugar, cholesterol.
In the meantime, Gelfand said more research needs to be done to find out "how skin disease severity affects the risk of developing insulin resistance, obesity, abnormal cholesterol levels and cardiovascular disease, and whether successful treatment of psoriasis alters these risks".

One such project, funded by the National Heart, Lung and Blood Institute is already planned, said Gelfand. The multi-center clinical trial will seek to discover if treatment of psoriasis affects arterial inflammation, cholesterol function and metabolic disease.

Written by Catharine Paddock PhD