Schizophrenia is a severe neurodevelopmental disorder with a worldwide prevalence of around 0.3-0.7% (1). The etiology of schizophrenia is unknown, but it is thought to result from a combination of complex genetic and environmental factors. This includes physical factors e.g., complications during pregnancy and birth, infection, and autoimmune disease; as well as psychological factors that may trigger psychosis, such as stress and drug abuse (2). Several neurotransmitter systems are thought to be involved in the pathogenesis, including dopamine, glutamate, GABA, and acetylcholine.
Schizophrenia is associated with substantial morbidity and mortality. Antipsychotics are the mainstay of treatment, however, their efficacy is poor for many patients. Antipsychotics are thought to exert their therapeutic effects by the post-synaptic blockade of D2 dopamine receptors in the brain.
The symptoms of schizophrenia fall in to three main categories: positive, negative, and cognitive. Positive symptoms are generally not found in healthy individuals, but may come and go or persist in individuals with schizophrenia. Positive symptoms include reality distortion (e.g., delusions, hallucinations), and thought disorders. These symptoms often respond well to treatment.
Negative symptoms are deficits in normal emotions and behavior, and may be mistaken for depression. Symptoms divide into reduced expression of emotion (e.g., speaking without moving or with a monotonous voice) and avolition (a lack of motivation to start or continue with a task). No treatment has established efficacy for these pathologies.
Cognitive symptoms may also be difficult to recognize. They include poor executive functioning (understanding information and using it to make decisions) and trouble focusing or paying attention. And again, no treatment has established efficacy.