Causes
There are several causal factors that may underlie the manifestation of schizophrenia. Not all individuals showing a higher risk to develop schizophrenia are finally becoming ill. In addition, a number of underlying conditions have been identified more recently that resemble the symptoms of schizophrenia, among the immune disorders and brain inflammation. However, as soon as an underlying condition has been identified, the syndrome is no longer named schizophrenia but e.g., organic psychotic syndrome with symptoms of schizophrenia. Some predisposing factors for schizophrenia are related to genetics and epigenetics (how your behaviors and environment can cause changes that affect the way your genes work), environmental factors, and drug use.
-
Hundreds of genes have been linked to schizophrenia, but they do not follow typical patterns of inheritance where disorders can be predicted with confidence. This is because no particular set of genes has yet been identified as causing the disorder. Most current genetic theories of schizophrenia assume that genes by themselves do not cause the disease, but rather make the person more susceptible to developing the disease if the person is also exposed to specific environmental factors.
Environmental risk factors encompass a range of stressors that occur during pregnancy and childbirth, exposure to infectious agents, traumatic experiences during childhood and adulthood, advanced paternal age, and substance abuse (Kahn et al., 2015; Cantor-Graae et al., 2005). The extent of the relationship between non-genetic factors and the development of schizophrenia is not yet fully understood, and the interplay between genetic and non-genetic factors differs among individuals.
-
Studies have also shown that cannabis use during adolescence, a critical period for brain development, may have a more significant impact. Longitudinal research has demonstrated an association between cannabis use and an increased risk of psychosis or schizophrenia later in life (Di Forti et al., 2009).
In a study conducted in the Netherlands, it was found that individuals with schizophrenia who use cannabis are more responsive to both the positive and negative effects of the drug compared to healthy individuals. While smoking cannabis provided temporary relief for the subjects with schizophrenia, it significantly exacerbated their psychotic symptoms (Henquet et al., 2010)
-
There are several hypotheses on the causes of schizophrenia that have been rejected over the years. So one needs to be careful not to subscribe to obsolete models to explain the condition.