What Causes It?

The three main theories regarding the causes of psychosis involve a person’s biology, any stress triggers in a person vulnerable to Psychosis, and the use of illicit street drugs.

Biology

Neurotransmitters

There is strong evidence that some psychoses involve a dysfunction in neurotransmitters in the brain. Neurotransmitters are the “chemical messengers” of the brain. They transmit impulses throughout the brain and the Central Nervous System. Of particular importance is the neurotransmitter Dopamine. Most anti-psychotic drugs that control the positive symptoms of Psychosis also block the transmission of Dopamine.

Genetics

Individuals whose close relatives experience Psychosis are themselves at increased risk. For example, the risk of developing Psychosis associated with Schizophrenia in the general population is approximately 1%, yet the children and siblings of those with Schizophrenia have respective lifetime risks of 13% and 9%.

Brain Changes

Changes have been found in the brains of some individuals with Schizophrenia, which appear to have been present since birth or early childhood. Possible causes of the changes include: genetic transmission, abnormal neurodevelopment and pregnancy or birth complications (e.g. exposure of mother to a virus during the second Trimester of pregnancy).

Stress and vulnerability

It is believed that individual vulnerability to psychosis combined with stress can lead to Psychosis in some people. Vulnerability to Psychosis can be increased if there is a family history, or as a result of an earlier effect on the brain, e.g. birth complications (oxygen deprivation of the baby) or head injuries.

The degree of vulnerability varies from person to person. Likewise, the amount of stress that may trigger Psychosis likely differs for each individual. For example, a person with a low vulnerability might withstand a large amount of stress without experiencing Psychosis, whereas a person with a high vulnerability might only withstand a minimal amount of stress without experiencing Psychosis.

Stresses can be such things as significant life events (e.g. death of a loved one, moving to a new city, etc.), abuse of alcohol and drugs or stressful living conditions (e.g. high levels of family conflict or financial problems). There is some evidence that severe psychological trauma (e.g. physical or sexual abuse) can trigger psychotic symptoms.

Street Drugs

Psychosis can be induced or made worse by illicit street drugs. For example, amphetamines and other stimulant drugs can cause psychotic symptoms such as paranoia, while other drugs, including cannabis, can increase a person’s natural vulnerability to psychotic symptoms.