[Depression and psoriasis].

Psychiatric co-morbidity is very frequently associated with psoriasis. Depression is observed in numerous patients with psoriasis. Early detection and treatment are very important. There is a vicious circle psoriasis- alteration of quality of life- depression, but psoriasis improvement is not always followed by an improvement of depression. A contrario, it is obvious that a depressive patient has a bad observance of treatment. Links between psoriasis and depression are not only psychopathological. Biological factors, such as increase of blood amounts of substance P and TNF or decrease of serotonine could also explain this association.