An artist’s representation of schizophrenia

Understanding schizophrenia

Read our Q&A to get up to speed on this commonly misunderstood condition

This article is particularly useful for background information on schizophrenia; for a first-person perspective of living with the condition, read our Real Voices interview with Edward Jones.

How many people in the UK have schizophrenia?

Around 220,000 people in England and Wales have a diagnosis of schizophrenia.

How many people in the world have schizophrenia?

Around 24 million people worldwide are affected by schizophrenia.

What is it? What do we know about it?

Schizophrenia is a term that covers many different symptoms – and may even encompass a number of different illnesses that we have yet to unravel.

Symptoms that lead to a diagnosis of schizophrenia can be both positive and negative. Negative symptoms are a reduction in normal activity and emotions, for example having a flat expression, showing no interest or pleasure in everyday life, not bothering to wash and speaking very little. These are often mistaken for depression. Positive – psychotic – symptoms are the ones we tend to associate with schizophrenia. They are typically what makes it possible to make a diagnosis of schizophrenia.

So what exactly is psychosis? Essentially, psychosis refers to a loss of contact with objectively verifiable reality, characterised by two separate phenomena: hallucinations and delusions. People hallucinate when they see or hear things that aren’t objectively there. Delusions are beliefs that are bizarre, irrational and intractable even in the face of contradictory evidence.

What do scientists think is happening in the brain?

Scientists at the University of Cambridge believe the hallucinations and delusions of psychosis are caused by a shift in the balance our brains try to achieve between the model of the world our minds have made and new sensory information coming in. If the sensory information is very salient, and our existing model of the world feels uncertain or fragile, we will update the model with the new information.

We now have a new model, which will affect how we process further incoming information. For example, a bright light might be interpreted as the presence of Jesus, or a red coat that looks too red on someone else might be interpreted as an expression of anger by the wearer. This is driven by changes in neurotransmitter levels and sometimes changes in brain structure.

Salience – the feeling of importance – is caused by increased levels of dopamine and reduced levels of glutamate, which ‘turn up the gas’. And changes or lesions in the frontal lobe (the part of the brain responsible for our understanding of the world and ourselves) lead to a ‘faulty’ or fragile model of the world. So increased ‘noise’ is dealt with by an impaired problem-solving system.

How is it treated?

Typically schizophrenia is treated with anti-psychotic medications that reduce dopamine levels in the brain – and hence the ‘salience’ of incoming information – in turn reducing hallucinations and delusions. Cognitive behavioural therapy (CBT) has also been shown to help.

Is it hereditary?

The exact causes of schizophrenia are unknown. It’s likely to be a combination of physical, psychological, environmental and genetic factors.

Many scientists and doctors believe people can be prone to schizophrenia but only develop it when there is a trigger, such as stress or drug abuse. It might also be caused by trauma in the womb caused by diabetes or pre-eclampsia in the mother.

Although schizophrenia tends to run in families, no individual gene seems to be responsible. Combinations of different genes are likely to make someone more prone to developing the disease – particularly if triggered by stress or drug taking.

If you have an identical twin who was brought up separately and develops schizophrenia you only have a 50:50 chance of developing it yourself. If your twin is non-identical you only have a one in seven chance of developing schizophrenia. This is higher than most people (who have a one in 100 chance), but by no means a foregone conclusion. Other factors are at play.

What organisations can help?

Mind, the mental health charity

Text: 86463


Advice line: 0300 123 3393

Rethink Mental Illness

Advice line: 0300 5000 927

Hearing Voices Network (information about strategies to cope with hearing voices and local support groups)

Tel: 0114 271 8210 

National Perceptions Forum



Tel: 0845 790 9090 (ROI: 1850 609 090)

Lead image:

An artist’s representation of schizophrenia. 

Adrian Cousins/Wellcome Images


About this resource

This resource was first published in ‘Thinking’ in August 2014.

Neuroscience, Psychology, Medicine, Health, infection and disease
Education levels:
16–19, Undergraduate, Continuing professional development