Many medical conditions have a relapsing and remitting nature. Most of those who suffer from the skin complaint psoriasis, for example, see their condition improve during the summertime because of the beneficial effects of sunshine.
However, the summer months may also be the time when patients first go to their GP with the dry, scaly plaques of psoriasis. I recall one lady coming to see me because she felt ashamed of the "dirty-looking" psoriasis patches when she wore short-sleeved shirts and skirts.
Indeed, the effects of psoriasis on quality of life are well-documented. Because of its chronic and relapsing nature and the unsympathetic reaction it sometimes gets, psoriasis is associated with depression. Patients perceive themselves as "unclean" and even infectious, which leads to reduced self-confidence and the avoidance of social situations where the affected skin has to be exposed.
Psoriasis patients often feel guilt and shame about their condition, and long-term sufferers can develop a distorted body image. They also tend to avoid sporting activities, such as swimming, which would add to their general well-being.
Psoriasis is a chronic skin condition which, in its commonest form, has the appearance of raised red patches with dry silvery scales. The rash can be very itchy, and usually affects the knees, elbows, scalp and nails. This form is known as plaque psoriasis (psoriasis vulgaris) and accounts for about 90 per cent of cases.
Psoriasis affects 3 per cent of the population, and is divided evenly between men and women. In 30 per cent of cases, a close relative will have psoriasis also.
The underlying cause of the complaint is not known, although some environmental risk factors have been identified. These include physical injury, emotional stress and drugs such as lithium and beta-blockers. A streptococcal throat infection is associated with the development of a particular type of psoriasis called guttate (drop-like). This form occurs more commonly in children and young adults. It affects the trunk and limbs and causes smaller lesions than the plaque variety. Three-quarters of guttate psoriasis cases resolve within months.
About one in two people with psoriasis will see changes in their nails, typically involving a "thimble-like" pitting. Changes in colour and even a complete separation of a nail from the nail-bed can occur. A condition similar to rheumatoid arthritis affects 6 per cent of patients with chronic psoriasis. So what can be done to help? Mild to moderate psoriasis can usually be controlled by topical treatment in the form of ointments and aqueous creams. Coal Tar is an old-fashioned but proven remedy, acting both as an anti-inflammatory treatment and as a remover of plaque. Shampoos containing tar are particularly effective for psoriasis of the scalp.
Topical steroids are useful for short treatment periods but, as always, care must be taken with potent steroid creams and ointments. A cream called Dithranol is especially suitable if the areas of plaque are large and well-defined. Dithranol is left on for 30 to 60 minutes per application to avoid burning of the skin. Calcipotriol ointment is a vitamin D analogue which can be used on all parts of the body apart from the face.
The more severe cases of psoriasis are treated with phototherapy and oral agents under the supervision of a specialist. Phototherapy uses medically refined ultra-violet light and should not be confused with lounging on a commercial sunbed. Not surprisingly, the availability of sunbeds has tempted people with psoriasis to "self-medicate" with ultra-violet light. One study in Newcastle found that up to 50 per cent of newly diagnosed psoriatics had used a sunbed in the recent past. The risks of this are well-documented.
Ultra-violet light (UVA) has been used by dermatologists since 1974 to treat severe psoriasis that is unresponsive to topical therapies. Because of this 25-year experience of UVA, we know that long-term exposure to ultra-violet light increases the risk of squamous cell cancer of the skin. There are also reports of malignant melanoma developing in patients years after their original exposure.
Whatever about the risks of UVA therapy under strict supervision, the careless use of sunbeds for self-medication is really playing with fire. Dermatologists are always careful to establish whether a patient is already using sunbeds before prescribing ultra-violet therapy.
Concurrent sunbed use is an absolute contra-indication to phototherapy. This is not just because of the increased skin cancer risk but because a chemical called psoralen (given to the patient to increase the effectiveness of the ultra-violet rays) can be activated by sunbed use. This could have fatal consequences.
If your psoriasis is not responding to topical treatment, do not be tempted into using a sunbed. Instead, talk to your doctor about referral to a dermatologist.
Dr Muiris Houston, Medical Correspondent, can be contacted at mhouston@irish-times.ie or messages can be left on tel: 01-6707711, ext. 8511. Dr Houston regrets that he cannot reply to individual medical problems