Psychological Medicine


Psychotic-like experiences in the general population: characterizing a high-risk group for psychosis

I. Kellehera1 c1 and M. Cannona1a2

a1 Department of Psychiatry, Royal College of Surgeons in Ireland, Dublin, Ireland

a2 Department of Psychiatry, Beaumont Hospital, Dublin, Ireland

Recent research shows that psychotic symptoms, or psychotic-like experiences (PLEs), are reported not only by psychosis patients but also by healthy members of the general population. Healthy individuals who report these symptoms are considered to represent a non-clinical psychosis phenotype, and have been demonstrated to be at increased risk of schizophrenia-spectrum disorder. Converging research now shows that this non-clinical psychosis phenotype is familial, heritable and covaries with familial schizophrenia-spectrum disorder. A review of the research also shows that the non-clinical phenotype is associated extensively with schizophrenia-related risk factors, including social, environmental, substance use, obstetric, developmental, anatomical, motor, cognitive, linguistic, intellectual and psychopathological risk factors. The criterion and construct validity of the non-clinical psychosis phenotype with schizophrenia demonstrates that it is a valid population in which to study the aetiology of psychosis. Furthermore, it suggests shared genetic variation between the clinical and non-clinical phenotypes. Much remains to be learned about psychosis by broadening the scope of research to include the non-clinical psychosis phenotype.

(Received March 23 2010)

(Accepted April 09 2010)

(Online publication May 19 2010)


c1 Address for correspondence: Dr I. Kelleher, Department of Psychiatry, Royal College of Surgeons in Ireland, Education and Research Centre, Beaumont Hospital, Dublin 9, Ireland. (Email: (Email: