Can We Detect Psychotic-like Experiences in the General Population?

The continuum model of psychosis posits that psychotic symptoms are distributed throughout the population, with diagnosable clinical disorder existing at a certain point along this continuum. The total continuum is made up mainly of non-clinical cases with clinical cases of psychosis representing only a small proportion of the total extended psychosis phenotype. This paper is a narrative review of studies of psychotic experiences in the general population. The evidence indicates reasonably high prevalence rates of psychotic experiences in the general population, substantially higher than the prevalence of psychotic disorders, and that they are associated with increased risk of future onset of diagnosable disorder, particularly when the experiences are persistent. Psychotic experiences in the general population share an extensive range of risk factors with schizophrenia and therefore provide a useful phenotype in which to study the aetiology of clinical psychosis. Some types of psychotic experiences, such as paranoid ideas, bizarre thinking and perceptual abnormalities, may indicate a greater level of risk for psychotic disorder than other psychotic experiences, such as magical thinking. There is a need for research that further explores the interplay between psychotic experiences and other risk factors (including psychological, environmental, neurocognitive and genetic factors) in the evolution of psychotic disorder, the types of psychotic experiences that are most associated with risk for clinical disorder, the specificity of risk associated with psychotic experiences, and the possible adaptive advantages of these experiences.