Causes - Schizophrenia

The exact causes of schizophrenia are unknown. A mix of factors can make a person more likely to develop it.

These include physical, genetic, psychological and environmental factors.

You may be more likely to get schizophrenia. A stressful or emotional life event might trigger a psychotic episode.

But it's not known why some people develop symptoms and others do not.

Increased risk

There are a number of things that increase the chances of schizophrenia developing.

Genetics (family history)

You may be more at risk of developing schizophrenia if other people in your family have it.

This does not mean you will develop schizophrenia. There are other things that may influence the development of schizophrenia.

Brain development

There are some differences in the structure of the brain for people with schizophrenia.

These changes do not happen in everyone with schizophrenia. They can happen in people who do not have a mental health difficulty.

But they suggest schizophrenia may partly be a disorder of the brain.

Neurotransmitters

Neurotransmitters are chemicals that carry messages between brain cells.

There's a link between neurotransmitters and schizophrenia. Medicines that change the levels of neurotransmitters can relieve some of the symptoms.

Pregnancy and birth complications

If you have schizophrenia, you are more likely to have had health complications when you were born.

These include:

• having a low birth weight
• being a premature baby
• not having enough oxygen (asphyxia) during birth

It may be that these things have some effect on brain development.

History of traumatic events

Early traumas in life increase the risk of psychosis.

These include:

• child sexual abuse
• physical abuse
• bullying

But not everyone who has had early trauma will develop psychosis. Also, not everyone who has psychotic experiences has experienced childhood abuse.

Triggers

Triggers are things that can cause schizophrenia to develop in people who are at risk.

Stress

The main triggers of schizophrenia are stressful life events, such as:

• bereavement
• losing your job or home
• divorce
• the end of a relationship
• physical, sexual or emotional abuse

These kinds of experiences do not cause schizophrenia. But they can trigger its development in someone who is already more likely to get it.

Drug use

Drugs do not directly cause schizophrenia. But harmful drug use increases the risk of developing schizophrenia, or a similar mental health difficulty.

Certain drugs may trigger symptoms of schizophrenia in people who are more likely to have it.

For example:

• cannabis
• cocaine
• LSD
• amphetamines

Using amphetamines or cocaine can lead to a psychotic episode. This can cause a relapse (setback) in people recovering from an earlier episode.

People under 15 who use cannabis regularly are up to 4 times more likely to develop schizophrenia by the age of 26. This is especially true for 'skunk' and other stronger forms of the drug.