Studies indicate that, in most cases, Psoriasis is inherited as incidences of Psoriasis are high among the relatives of affected individuals. It is thought that certain inherited genes may be linked to Psoriasis, but the exact way this happens is not yet understood.
Infections are often involved in the development of psoriatic symptoms. Bacteria, particularly Streptococci, are the most commonly implicated pathogens, and are linked to Guttate Psoriasis. Human Immunodeficiency Virus (HIV), although not a direct cause of Psoriasis, is known to increase the likelihood of developing more severe Psoriasis in cases where the condition already exists.
Stress & injury
Psychological stress may worsen the condition, and, in some cases, may be enough to trigger it, whilst injury to the skin can trigger psoriatic skin changes at the spot of trauma.
Some medications can cause or trigger Psoriasis – particularly lithium, antimalarial drugs and medication for high blood pressure – can trigger Psoriasis. Psoriasis symptoms can also ‘rebound’ when Psoriasis medication is suddenly stopped. In these instances, the symptoms are often severe.