The exact cause of psoriasis is not fully understood. The processes involved in the development of psoriasis as largely understood. Although cold climate and some form of injury can aggravate the problem they cannot be labeled as the cause of disease. The precise cause of psoriasis continues to elude the medical fraternity. However, ongoing research in this field has improved our understanding of this disease to some extent. The recent discoveries point to an abnormality in the functioning of key white cells in the blood stream triggering inflammation in the skin. Because of the inflammation, the skin sheds too rapidly, every three to four days.
Actually, psoriasis stems from internal disharmony of the body (in terms of disturbed immunity and genetic predisposition) topped with some environmental triggers.
1. Defective immune system: Recent research indicates that psoriasis is likely to be a disorder of the immune system. This system includes a type of white blood cell, called a T cell, that normally helps protect the body against infection and disease. Scientists now think that, in psoriasis, an abnormal immune system causes activity by T cells in the skin. These T cells trigger the inflammation and excessive skin cell reproduction seen in people with psoriasis.
2. Genetics and heredity: In about one-third of the cases, psoriasis is inherited. Often, the person with psoriasis has a parent or grandparent who also has the condition. In terms of probability it has been estimated that a person with one affected parent has about a 10% chance of also being affected. Having two parents with psoriasis increases the chances to about 30%.
Researchers are studying large families affected by psoriasis to identify a gene or genes that cause the disease. (Genes govern every bodily function and determine the inherited traits passed from parent to child.)
1. Climate: Studies indicate that cold weather may be a predisposing effect or trigger for psoriasis, in contradistinction to hot and sunny climate that appears to be beneficial.
2. Infections: Both dermatological and systemic infections have been known to trigger the onset of psoriasis or a worsening of psoriasis. Systemic infections that have been associated with triggering include viral upper respiratory disease, streptococcal pharyngitis (strep throat), and human immunodeficiency virus (HIV). Staphylococcal skin infections (boils) have been a trigger.
3. Stress: Psychological stress is the cause as well as out come of disease like psoriasis. It is a well-known fact that there is inseparable bond between mind and body and psyche plays vital role in maintaining health or causing diseases.
It is a common experience in practice of patient reporting the onset of psoriasis following major stress like divorce, death of close relatives, change of job, unhealthy family relationships etc and this perception of patients that psychological stress can worsen psoriasis has been supported in clinical studies.
4. Certain medicines: Certain medicines, most notably beta-blockers, which are used to treat high blood pressure, and lithium or drugs used to treat depression, may trigger an outbreak or worsen the disease. The drugs may be listed as: lithium, anti-malarials, mepacrine, NSAIDs, beta-blockers, alcohol.
5. Physical trauma: People often notice new spots 10 to 14 days after the skin is cut, scratched, rubbed, or severely sunburned. Analysis of patient records has indicated that up to 50 percent of persons with psoriasis have had a 'Koebner's phenomenon' experience - that is, have had a psoriatic lesion develop at the site of an injury or skin condition.
A broad range of skin injuries and skin conditions have been linked with Koebner's phenomenon: