[Risk factors for the development of schizophrenia]

Schizophrenia is a severe psychiatric disorder with lifetime prevalence about 1 %. Usually, the disorder starts during the adolescence, however it is estimated that around 30 % of first-onsets are beyond the age of 40. The incidence of males is a little bit higher in the adolescence, while from the age of 40 the incidence in females is higher. In this context, the pathogenesis and development of schizophrenia is a complex model of gene-environment interactions and is not, like it was postulated in the earlier "One-Hit" or "Two-Hit" models caused by exclusively one or two single events. The risk to develop schizophrenia is composed of a biological predisposition with multi-genetic risk factors and changes in the neurotransmitter system, immunological influence factors and psychosocial risk factors. Genetic risk factors, perinatal risk factors and complications during birth could increase the probability of the disease. Besides these early risk factors traumatic events during childhood and especially risk factors like cannabis abuse that occur during adolescence which is a sensitive phase in the brain development could influence onset, development and relapse risk of the disease. If timing and sum of the single risk factors interact, they can cause the disturbance of neuronal regeneration and lead to schizophrenia, but the whole interaction of this multifactorial process is still not fully understood.