This guideline covers the treatment and management of psychosis and schizophrenia and related disorders in adults (18 years and older) with onset before 60 years. The term 'psychosis' is used in this guideline to refer to the group of psychotic disorders that includes schizophrenia, schizoaffective disorder, schizophreniform disorder and delusional disorder. The recognition, treatment and management of affective psychoses (such as bipolar disorder or unipolar psychotic depression) are covered by other NICE guidelines. The guideline does not address the specific treatment of young people under the age of 18 years, except those who are receiving treatment and support from early intervention in psychosis services; there is a separate NICE guideline on psychosis and schizophrenia in children and young people.

Psychosis and the specific diagnosis of schizophrenia represent a major psychiatric disorder (or cluster of disorders) in which a person's perception, thoughts, mood and behaviour are significantly altered. The symptoms of psychosis and schizophrenia are usually divided into 'positive symptoms', including hallucinations (perception in the absence of any stimulus) and delusions (fixed or falsely held beliefs), and 'negative symptoms' (such as emotional apathy, lack of drive, poverty of speech, social withdrawal and self-neglect). Each person will have a unique combination of symptoms and experiences.

Typically there is a prodromal period, which precedes a first episode of psychosis and can last from a few days to around 18 months. The prodromal period is often characterised by some deterioration in personal functioning. Changes include the emergence of transient (of short duration) and/or attenuated (of lower intensity) psychotic symptoms, memory and concentration problems, unusual behaviour and ideas, disturbed communication and affect, and social withdrawal, apathy and reduced interest in daily activities. The prodromal period is usually followed by an acute episode marked by hallucinations, delusions and behavioural disturbances, usually accompanied by agitation and distress. Following resolution of the acute episode, usually after pharmacological, psychological and other interventions, symptoms diminish and often disappear for many people, although sometimes a number of negative symptoms remain. This phase, which can last for many years, may be interrupted by recurrent acute episodes that may need additional pharmacological, psychological and other interventions, as in previous episodes.

Although this is a common pattern, the course of schizophrenia varies considerably. Some people may have positive symptoms very briefly; others may experience them for many years. Others have no prodromal period, the disorder beginning suddenly with an acute episode.

Over a lifetime, about 1% of the population will develop psychosis and schizophrenia. The first symptoms tend to start in young adulthood, at a time when a person would usually make the transition to independent living, but can occur at any age. The symptoms and behaviour associated with psychosis and schizophrenia can have a distressing impact on the individual, family and friends.

Psychosis and schizophrenia are associated with considerable stigma, fear and limited public understanding. The first few years after onset can be particularly upsetting and chaotic, and there is a higher risk of suicide. Once an acute episode is over, there are often other problems such as social exclusion, with reduced opportunities to get back to work or study, and problems forming new relationships.

In the last decade, there has been a new emphasis on services for early detection and intervention, and a focus on long-term recovery and promoting people's choices about the management of their condition. There is evidence that most people will recover, although some will have persisting difficulties or remain vulnerable to future episodes. Not everyone will accept help from statutory services. In the longer term, most people will find ways to manage acute problems, and compensate for any remaining difficulties.

Carers, relatives and friends of people with psychosis and schizophrenia are important both in the process of assessment and engagement, and in the long-term successful delivery of effective treatments. This guideline uses the term 'carer' to apply to everyone who has regular close contact with people with psychosis and schizophrenia, including advocates, friends or family members, although some family members may choose not to be carers.

Psychosis and schizophrenia are commonly associated with a number of other conditions, such as depression, anxiety, post-traumatic stress disorder, personality disorder and substance misuse. This guideline does not cover these conditions. NICE has produced separate guidance on the management of these conditions (see the NICE topic page on mental health and behavioural conditions).

The guideline will assume that prescribers will use a drug's summary of product characteristics to inform decisions made with individual patients.