Psychotic experiences such as hallucinations and delusions are either “more common than previously thought” in the general population or “infrequent in the general population,” depending on whose press release is consulted about a study in JAMA Psychiatry. And the significance of the findings seemed to differ in each press release, too.
Led by the University of Queensland and Harvard Medical School, a large, international team of researchers examined data from the World Health Organization World Mental Health Surveys from 2001 through 2009. Respondents included 31,261 adults from 18 countries. Participants were asked about lifetime and 12-month prevalence and frequency of six types of psychotic experiences (PEs), including hallucinatory and delusional experiences.
The researchers found that 5.8% of people reported having a psychotic experience in their lives.
“Hallucinations and delusions in the general population are more common than previously thought,” stated a press release from the University of Queensland. In this press release, Brain Institute researcher and lead author John McGrath was quoted saying, “We used to think that only people with psychosis heard voices or had delusions, but now we know that otherwise healthy, high-functioning people also report these experiences… So it’s incredibly interesting that not only is hearing voices more common than previously thought, but it’s not always linked to serious mental illness.”
In the press release from JAMA Network Journals, those quotes from McGrath were not present, and there was no discussion of “healthy” people having psychotic experiences. “Psychotic experiences were infrequent in the general population,” began that press release, emphasizing repeatedly how “rare” the experiences were. A quote from McGrath explained how the findings could help better determine who was at risk for developing psychotic mental disorders.
McGrath JJ, Saha S, Al-Hamzawi A, and et al. “Psychotic Experiences in the General Population: A Cross-National Analysis Based on 31 261 Respondents from 18 Countries.” JAMA Psychiatry, May 27, 2015. doi:10.1001/jamapsychiatry.2015.0575. (Full text)
Hallucinations and delusions more common than thought (University of Queensland press release on MedicalXPress, May 27, 2015)
Global study finds psychotic experiences infrequent in general population (JAMA Network Journals press release on MedicalXpress, May 27, 2015)