Outlook:

Psoriasis is lifelong and is not curable. Although it is also marked by rapid cell growth, psoriasis is neither cancerous nor contagious.

In general, studies report the following features of its course:

• The condition almost always relapses. In a few cases, large areas of plaque can persist for years.
• Psoriasis nearly always goes into remission, however, often clearing on its own.
• Increased levels of estrogen may be responsible for this improvement. Relapse may occur after giving birth.

Emotional and Social Consequences

The emotional and social consequences of psoriasis should not be underestimated.

• Many patients have severe humiliation and depression if plaques are visible. Some even withdraw from society and become isolated.
• Some patients are forced to leave their jobs and go on disability if the condition becomes incapacitating.

Researchers have reported the following:

• Surveys of patients with psoriasis report a negative mental and physical impact that is nearly equivalent to that of other major chronic conditions, including cancer, high blood pressure, diabetes, heart disease, and depression.
• In one study, 75% of patients reported that psoriasis hurt their confidence.
• Another study reported that 8% of people with psoriasis felt their life was not worth living.

Substance Abuse

Some patients, particularly men, use alcohol and smoking as self-medication to reduce the emotional consequences of psoriasis. In fact, studies have found that people with psoriasis have higher mortality rates, mostly from heavy drinking. Smoking has also been cited as a major risk, particularly for pustular psoriasis. Some experts believe that drinking and smoking may actually cause biological damage that contributes to psoriasis itself.

However, smoking may delay the onset of psoriatic arthritis in some patients, depending on when they started the habit. Psoriatic arthritis tends to occur about a decade after psoriasis develops. One review of psoriasis patients showed that the condition appeared after about 13 years in nonsmokers, compared to 23 years in those who began smoking after the first onset of psoriasis. Psoriatic arthritis appeared after 8 years in people who smoked before developing psoriasis.

Physical and Medical Complications of Psoriasis

Folate Deficiency in Severe Psoriasis. Severe psoriasis can cause folate deficiency. Folate is a B vitamin that is important for nerve function, and prevents birth defects. It also prevents elevations of homocysteine, a factor that may play a critical role in heart disease.

Skin Cancers. Patients with severe psoriasis (who receive medications that affect the whole body) may be at higher-than-normal risk for developing cancers, primarily skin cancers and lymphomas. The risk is not any higher in patients with milder psoriasis. There is some indication, however, that patients with psoriasis have a higher risk for non-melanoma skin cancers, regardless of treatments.

Obesity, diabetes, and heart risks: There are also increased risks of diabetes, heart disease, heart attacks, and cancer in patients with psoriasis. It is not yet known whether there are genetic links between psoriasis and some of these conditions. The connection may also have to do with shared risk factors, such as smoking and obesity. Patients with moderate-to-severe psoriasis should be screened, and possibly treated, for cardiovascular risks.

Complications of Erythrodermic and Pustular Psoriasis

Impaired Temperature Regulation. Erythrodermic psoriasis (in which psoriasis covers the entire skin) can cause abnormalities in the body's ability to regulate temperature.

Zumbusch Psoriasis. A combination of erythrodermic and pustular psoriasis causes a serious condition called Zumbusch psoriasis:

• The condition can develop abruptly.
• Symptoms may include fever, chills, weight loss, and muscle weakness.
• Patients may develop excessive fluid build-up, protein loss, and electrolyte imbalances. In such cases, hospitalization is required. Fluid and chemical balances must be restored and temperature stabilized as soon as possible.

Zumbusch psoriasis can be life threatening, particularly in the elderly. The condition is very rare in children and, if it occurs, tends to improve more quickly than in adults, possibly even without medication.

Complications of Psoriatic Arthritis

Most cases of psoriatic arthritis (PsA) are mild, but complications can occur:

• Severe joint deformity and destruction (called arthritis mutilans) may develop, generally in the small joints of the hands and feet. This happens in about 5 - 16% of patients. Psoriasis patients with other arthritic conditions (osteoarthritis or rheumatoid arthritis) in the joints of the fingers tend to have a higher risk.
• People with PsA may have a higher risk for respiratory illnesses.

Some earlier studies indicated that patients with psoriatic arthritis had a shorter lifespan than the general population, but more recent studies found no significant difference.