There are more cases of the disease in relatives of people with psychosis. Having a first relative with psychosis increases the risk of developing a psychotic disorder. However, there may be no family history of psychosis, or one could not develop the disease despite the affection of several family members.
Psychotic symptoms have been linked to overactive dopamine activity or greater sensitivity to dopamine in the brain. Other theories of the neurological causes of psychosis include disrupted communication between areas of the brain, and some findings have shown enlarged ventricles and reduced volume of some brain areas. Psychosis has been linked to complications during pregnancy or childbirth and nutritional deficiencies or head trauma in childhood. Despite such findings, the causes of psychosis are not yet fully understood and more work needs to be done.
Environmental factors such as living in an urban environment, experience of traumatic events, and substance abuse have been linked with a higher risk of developing psychosis.
Stress is thought to contribute to the likelihood that someone will develop psychotic symptoms or may contribute to the worsening of psychotic symptoms in those with psychosis. People with psychosis may also be more sensitive to stress.