Schizophrenia is a chronic, severe and disabling mental health problem that is found all over the world, affecting roughly one per cent of the population. Although men and women are equally affected, men tend to experience symptoms at a slightly earlier age than women, often in their late teens. The symptoms of schizophrenia can be broadly classified as positive, negative or cognitive. Positive symptoms are psychotic behaviours including hallucinations, particularly hearing voices; delusions, or false yet strongly held personal beliefs; and disorders of thinking. Negative symptoms, which are harder to recognise and can be mistaken for depression, include blunted emotions; lack of motivation; an inability to take an interest in, or enjoy, life; and poor social functioning. Cognitive symptoms include problems with working memory and trouble focusing or paying attention.
Antipsychotic medications, which have been available since the mid-1950s and work primarily by suppressing dopamine activity, are the current mainstay of treatment for schizophrenia. These are generally able to reduce hallucinations and delusions and allow patients to function more effectively and appropriately. They are, however, less helpful with negative symptoms such as reduced motivation and emotional expressiveness, which for many patients contribute more to poor quality of life and functional disability than do positive symptoms.