Psoriasis – mild, moderate and severe – affects more than one million people in Canada, or 3% of the population (the disease can also affect children and even infants). While the symptoms of psoriasis can appear at any age, research shows the disease usually strikes between the ages of 15 and 35. In 75% of cases, it starts before the age of 40.

What is psoriasis?
Psoriasis is an inflammatory disease in which skin cells replace themselves extremely quickly. New skin cells are generated 8 times faster than normal, causing a build up of squamous cells (flat scaly cells shed by the skin) at the skin’s surface. Psoriasis is a chronic, non contagious disease that we still do not know how to cure completely.

There are several different types of psoriasis. The most common is plaque psoriasis, characterized by raised reddish patches covered in silvery scales (dead cells). Some 80 90% of psoriasis sufferers have this type.

Up to 30% of psoriasis sufferers also have psoriatic arthritis, which causes inflammation of the joints.

Causes and diagnosis of psoriasis
The exact cause of psoriasis is still not fully understood. It seems that heredity plays a role in 40 60% of cases, although many people who develop the disease show no family history of it. Several factors can trigger the disease, worsen its symptoms, or cause a flare up, including cold temperatures and psychological stress.

In psoriasis, an abnormal response by the immune system causes a rapid increase in immature cells in the skin (keratinocytes) and inflammation. In plaque psoriasis, this inflammation causes the formation of red patches and dry, silvery squamous cells on different parts of the body – the scalp, elbows, knees, palms and soles of the feet.

To make a diagnosis, the physician will sometimes examine a tissue sample from the patch under the microscope.

Signs and symptoms
Approximately half of all psoriasis sufferers experience some changes in their finger and toe nails. The nails may develop small dents on the surface (giving them the appearance of a thimble), become discoloured or deformed, or even fall off. Onychomycosis or infection of the nail, which can occur in both psoriasis sufferers and non-sufferers, may also lead to nail changes. However, the treatment for onychomycosis is different than that used to improve the appearance of nails altered by psoriasis, hence the importance of proper diagnosis.

Living with psoriasis
Psoriasis is a disease that can have major physical and psychological repercussions on the quality of life of those suffering from it.

According to a Canadian Memorandum of Understanding published in the Journal of Cutaneous Medicine and Surgery, psoriasis can be considered moderate-to-severe if it significantly diminishes the quality of life of the person affected, no matter what percentage of the body surface is affected.  As situations that significantly impact quality of life, the researchers list functional incapacity of the hands or feet, pronounced pruritus (itching) or discomfort, or psoriasis that negatively affects self-esteem due to the body areas affected.

According to a statistical survey conducted in the US by the National Psoriasis Foundation, moderate-to-severe psoriasis significantly impacts the life of those suffering from it. The disease is considered to be a moderate-to-severe problem in the life of 75% of those affected. Some 26% of respondents modified or stopped activities of daily living because of their psoriasis.

Treatments
While there is still no cure for psoriasis, there are a variety of treatments available to help reduce the underlying inflammation and control desquamation (scaling).

Topical treatments are useful in cases of light-to-moderate psoriasis (affects at most 5% of the body surface). These are applied directly to the affected area(s). They can also be used in combination with other treatments. However, for people suffering from moderate-to-severe psoriasis, topical treatments may not be enough to control the symptoms. Other treatments may be needed, such as phototherapy in which the skin is exposed to ultraviolet rays of a specific wavelength. Conventional systemic treatments are also an option. Finally, there is now a new class of drugs for treating moderate-to-severe psoriasis – biological agents. These specifically target components of the immune system believed to be involved in the disease.