Schizophrenia and related psychotic disorders – brief psychotic disorder, delusional disorder, schizoaffective disorder, schizophreniform disorder, and schizotypal personality disorder – are characterised by psychotic symptoms, and often by negative symptoms and cognitive dysfunction.
Causes of Schizophrenia
What precisely causes schizophrenia is not known, but current research suggests a combination of hereditary and environmental factors.
Fundamentally, however, it is a biologic problem (involving changes in the brain), although certain external factors such as major life stresses or substance abuse can serve as triggers
Factors that make people vulnerable to schizophrenia include the following:
- A genetic predisposition;
- Problems that occurred before, during, or after birth, such as influenza in the mother during the 2nd trimester of pregnancy, lack of oxygen during delivery, a low birth weight, and incompatibility of the mother’s and infant’s blood type;
- Infections of the brain; and
- Cannabis use in early teen years.
Individuals who have a parent or sibling with schizophrenia have about a 10% risk of developing the disorder, compared with a 1% risk among the general population.
An identical twin whose co-twin has schizophrenia has about a 50% risk of developing schizophrenia.
These statistics suggest that heredity is involved.