Schizophrenia is a biological disease that directly affects the brain. Brain scans of people with long term, untreated schizophrenia have shown a range of changes in the brain, including reduced brain size and grey matter. Research into schizophrenia and the brain is ongoing.
One theory about the causes of schizophrenia is called the ‘dopamine hypothesis’. Dopamine is a neurotransmitter (chemical messenger) that plays a significant role in things like learning, mood, sleep, attention, movement, motivation and reward/pleasure. It’s theorised that dopamine dysfunction (too much or too little) may play a role in some of the symptoms of schizophrenia.