It is possible that clinical phenomena associated with mental illness lie on a continuum with normality. Along these lines, several recent reports have studied the prevalence of hallucinations and other psychotic symptoms in the general population. A recent meta-analysis of risk factors to develop subclinical psychotic symptoms shows associations with male sex, migrant status, living in urban centres, developmental stage, psychoactive drug use, and child and adult social adversity, 1 all of which are risk factors for schizophrenia as well. This study also revealed that about 75% to 90% of psychotic experiences are transitory and disappear over time. The transient developmental expression of psychosis (psychosis proneness) may persist and become clinically relevant (impairment). This process depends on the degree of environmental risk to which the person is eventually exposed.
Continuum Between Normality and PathologicalThe lifetime prevalence of schizophrenia is known to be about 1%. This paper reviews the presence of psychotic features in the nonclinical population. The results of a literature review suggest that delusional and hallucinatory experiences are more common in the general population than we may think, and that there could well be a symptomatic continuum between people who have and people who have not been diagnosed with indisputable psychotic disorders. In the nonclinical population, voices are mainly positive and nonthreatening. Conversely, in the psychiatric population, they tend to be frequent, intrusive, and distressing. We address the question of voices considered as various human experiences and describe the emergence of the nonclinical group of people who hear voices. We also review the pathophysiology of auditory hallucinations as an illustration of a neurophysiological anomaly, which is useful to understand psychosis or schizophrenia. The main obstacle in the category-specific thought is that it remains impossible to unmistakably demarcate the border around schizophrenia. It is evident that the creation of a boundary is always possible by using arbitrary criteria that improve interrater reliability but exclude a considerable number of people who share multiple common features with diagnosed people.Can J Psychiatry. 2009;54(3):140-151.
Highlights· Psychotic symptoms can be considered as a dimension of general human experience. · Psychosis can be understood as one of many dimensions of schizophrenia. · Knowledge of a person's social, cultural, and developmental context is fundamental when evaluating psychotic symptoms.
