The association between negative symptoms, psychotic experiences and later schizophrenia: a population-based longitudinal study.
BACKGROUND
Psychotic experiences are common in the general population, and predict later psychotic illness. Much less is known about negative symptoms in the general population.


METHODS
This study utilized a sample of 4,914 Israel-born individuals aged 25-34 years who were screened for psychopathology in the 1980's. Though not designed to specifically assess negative symptoms, data were available on 9 self-report items representing avolition and social withdrawal, and on 5 interviewer-rated items assessing speech deficits, flat affect and poor hygiene. Psychotic experiences were assessed using the False Beliefs and Perceptions subscale of the Psychiatric Epidemiology Research Interview. Psychiatric hospitalization was ascertained 24 years later using a nation-wide psychiatric hospitalization registry.


RESULTS
After removing subjects with diagnosable psychotic disorders at baseline, 20.2% had at least one negative symptom. Negative symptoms were associated with increased risk of later schizophrenia only in the presence of strong (frequent) psychotic experiences (OR = 13.0, 9% CI: 2.1-79.4).


CONCLUSIONS
Negative symptoms are common in the general population, though the majority of people with negative symptoms do not manifest a clinically diagnosed psychiatric disorder. Negative symptoms and psychotic experiences critically depend on each other's co-occurrence in increasing risk for later schizophrenia.
Department of Psychiatry, Sheba Medical Center, Tel-Hashomer, Israel.
Nomi
N
Werbeloff
Department of Psychiatry and Mailman School of Public Health, Columbia University, New York, New York, United States of America; New York State Psychiatric Institute, New York, New York, United States of America.
Bruce P
BP
Dohrenwend
Division of Mental Health Services, Ministry of Health, Jerusalem, Israel.
Rinat
R
Yoffe
Department of Psychiatry and Psychology, Maastricht University Medical Centre, Maastricht, The Netherlands; Department of Psychosis Studies, King's College London, King's Health Partners, London, United Kingdom.
Jim
J
van Os
Department of Psychiatry, Sheba Medical Center, Tel-Hashomer, Israel.
Michael
M
Davidson
Department of Psychiatry, Sheba Medical Center, Tel-Hashomer, Israel.
Mark
M
Weiser
D000328:Adult; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011618:Psychotic Disorders / Q000150:complications / Q000453:epidemiology / Q000503:physiopathology / Q000523:psychology; D012042:Registries; D012559:Schizophrenia / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology