2 Clinical need and practice

2.1 Psychosis is not a diagnosis in itself but a term used to describe a group of conditions in which severe symptoms of mental illness such as delusions and hallucinations occur, accompanied by the inability to distinguish between subjective experiences and reality. Usually people with psychotic symptoms lack insight into their condition. Psychosis can develop at any age from childhood to late old age. First-episode psychosis refers to the first time that a person presents with psychotic symptoms. However, it is often difficult to identify the precise time of onset. The current definition of 'first episode' could include people who have been treated for many years without remission as well as those who have had psychosis for only a short time and have not yet received treatment.

2.2 Psychosis sometimes occurs in association with the use of psychoactive drugs or with certain conditions, such as space-occupying lesions in the brain (a benign or malignant tumour, a cyst or an abscess), strokes, Alzheimer's disease, head injury or encephalitis. Psychoses that occur as a result of physical illness and are associated with structural changes to the brain are sometimes referred to as 'organic psychoses'. All other psychoses, including those where the diagnosis is schizophrenia or bipolar disorder, are referred to as 'functional psychoses'. The causes of psychosis vary with age and sex. Young adults who develop psychotic symptoms are most often diagnosed with functional psychoses, while organic psychoses are more common in older people. It is thought that psychosis is associated with an organic cause in 5–10% of people who present with symptoms.

2.3 The prevalence of psychosis varies with age and sex. Hospital Episode Statistics from the UK show that 0.2% of episodes of psychosis occur in people in the age range 0–14 years, 83.3% in the age range 15–59 years, and 16.5% in people aged 60 years and above. In the UK, 59% of finished consultant episodes (a period of admitted patient care under a consultant or allied healthcare professional within an NHS trust) for psychosis occur in men and 41% in women. Information on the incidence of psychosis in the UK is mostly related to schizophrenia and other functional psychoses rather than all psychoses. A study in Nottingham on the incidence of first-episode psychotic disorders in two cohorts (1978–1980 and 1992–1994) found that the age-standardised incidence rate for schizophrenia and related disorders was 0.14 per 1000 per year.

2.4 Mortality figures for all psychoses are not available; however, the mortality rates with schizophrenia as an underlying cause in the UK (1996–2004) were estimated at 0.7 per million for men and 0.8 per million for women. It is also estimated that the suicide rate for psychosis is around 7.52 per 1000 patient years (based on a small sample study), that the lifetime suicide rate for people with psychosis is 4% and that the lifetime suicide attempt rate is 22%.

2.5 People with psychosis tend to have a poor quality of life as a result of severe problems with social functioning and meeting the demands of daily life. People with psychosis may be reluctant to disclose or accept their condition because of lack of insight or the stigma attached to mental illness. The problems associated with psychosis can also place a significant burden on the person's family and carers.

2.6 Current management for psychosis aims to promote functional recovery and reduce relapse rates; it includes standard physical, mental state, neurological and laboratory examinations. Acute onset and delirium can be indications of an organic cause of psychosis. Where an organic cause is suspected, standard practice of care involves appropriate confirmatory tests. This may or may not include routine use of structural neuroimaging techniques. Where no organic cause for psychosis is found, it is assumed that a person has functional psychosis. Treatment of psychosis usually involves psychological and pharmacological approaches. There is, however, variation in service structure and delivery, the treatment and support offered, and the resources available across clinical practices.