There is no single answer to what causes psychosis. However there is a lot of information available which can help it be understood. This information has resulted from scientific/medical research and the experiences of professionals who work with people with personal experiences of psychosis.

The way that psychosis is understood determines which approaches are chosen to treat it. There are many theories that try to explain what causes it. It can sometimes be related to a specific trigger such as taking drugs, lack of sleep or a head injury, but often there is no single apparent reason.

Whatever the underlying ‘cause’ it can be helpful to view psychosis as a malfunctioning in normal psychological processes that everyone uses to perceive things, perform every day tasks, interact with others, think and speak.

Techniques that influence these processes can help regain control and reduce distressing psychotic symptoms.

The ‘stress vulnerability model’ is the most widely regarded explanation of how psychosis arises. It states that differences in biology and thought processes mean that everybody has individual levels of vulnerability– a threshold. People can be pushed over their threshold and experience psychosis when their resources for coping with stress are exhausted.

Imagine person A has a pint glass and person B has a bucket (these containers represent how vulnerable each person is to developing psychotic experiences). Stress (represented by water) flows into the containers. The overspill (psychotic experiences) will depend on how fast the water is flowing (the amount of stress) and also how large each container is (how vulnerable each person is).

The more vulnerable person needs less stress to experience psychosis, but they can avoid it by effectively managing and reducing stressors in their life. These experiences can, and do, happen to anyone!