Psoriasis is a skin disease that has plagued humanity through the ages, yet we still don’t know what causes it. We do know that it is inherited and in no way contagious
By Dr. Scott Murray and Trish Murray

John Corbett doesn’t wear shorts if he can help it. It’s one of the coping strategies he developed at an early age to hide the fact that he has psoriasis. Now that he’s in his 30s, he’s relieved to have survived the anguish of childhood, when other children used to stare at the plaque on his knees in gym class, and steer clear or hurl taunts. He managed to struggle through the teenage dating years when it’s tough enough on healthy kids to overcome a sense of awkwardness and isolation. It’s worse when the girl you like is afraid to hold hands because she might catch something. And, says Corbett, just try to find a hairdresser who doesn’t first pull on rubber gloves before washing a scalp flaky with scales. Even today, Corbett occasionally runs into conflict at the sheet-metal plant where he works, because colleagues don’t want to be on the assembly line near him.

In Biblical times, psoriasis was lumped together with leprosy, and like lepers, sufferers were isolated and forced to ring a bell before walking down a street so that healthy people could avoid them. Thousands of years later, not much has changed, as Corbett can attest. Even though the skin disease is not contagious, people don’t know much about it and still think they can get it through contact. It’s a disease that, despite its longevity, is surprisingly shrouded in mystery.

“I recently spoke to twin adult males, one brother has psoriasis, one doesn’t,” says Judy Misner, founder of the national Psoriasis Society of Canada, Halifax. “The one brother said to me, ‘Our whole lives we’ve always done everything together and yet my brother doesn’t understand my psoriasis.’”
What exactly is psoriasis? It’s a skin disease that causes inflammation and scaling on various body parts. Clues to look for include a scalp that flakes and itches despite dandruff remedies, pustular lesions on palms or feet, and thick, misshapen finger- or toenails. In its classic form, psoriasis creates thick red patches of skin, usually at the scalp, elbows and knees. Sufferers may find silvery scales in spots and the tendency for those spots to bleed slightly if the scale is removed. The lesions look sore and red, but they’re usually symptom-free. A few patients complain that the disease makes them itch.
Psoriasis affects about two percent of the world’s population and an estimated one million Canadians, so it’s likely that someone you know suffers from it. One of the most common causes of joint disease is actually a rarer form of psoriasis called psoriatic arthritis. None of the types of psoriasis are caused by infection, and none are contagious in any way.

So what does cause it? Therein lies the mystery. What science does know is that it can strike people at any age, regardless of hygiene or allergies. It tends to run in families, which has led to ongoing research to try to isolate the responsible genes. The medical profession suspects that psoriasis is an autoimmune disorder, where the body makes unwanted antibodies that attack the skin and sometimes the joints. Some medications, such as beta blockers and lithium, can make psoriasis worse. Stress and trauma can certainly trigger a bout, and the disease often flares after an attack of strep throat.

Unfortunately, nobody can change their family history — the main factor that leads to psoriasis. If it has a long history in your family, chances go up that you’ll get it. Research suggests that psoriasis is a bit worse in red-meat eaters, and improves with eating fish and fish oils, but this trend is mild, at best. Patients who take fish-oil supplements often note some benefit. Alcohol appears to make it worse and good general health care — being fit, eating a balanced diet and reducing stress in your life — can help and is encouraged. Psoriasis can grow worse under direct skin trauma: try to avoid rubbing or picking at the spots.

It seems like there’s an ever-expanding range of therapies to treat psoriasis, and John Corbett rolls his eyes when he talks about them, insisting he’s tried them all. For years tar, the tar-like substance anthralin and steroid creams were the mainstays of treatment. Today, ultraviolet therapy and oral medications like methotrexate, vitamin-A derivatives and cyclosporine are often prescribed for advanced cases. In the last few years new creams like calcipotriol, a vitamin-D derivative, and tazaratine, a vitamin-A derivative, offer fresh hope. At the same time, patients get frustrated when a remedy works well for a friend, but proves useless against their psoriasis. It takes an individualized approach and appreciation for each treatment’s subtle variation to select the correct one for each case.

A lot has changed in the care of psoriasis over the past few years, and it’s a good time to review available treatments with a dermatologist or general practitioner. Or call the Psoriasis Society of Canada in Halifax at 1-800-656-4494, or the Psoriasis Foundation of Canada in Ottawa at 1-800-265-0926.

Trish Murray is a Halifax writer; Dr. Scott Murray is a dermatologist in private practice, who teaches at Dalhousie University.