Citation

Reichenberg A, Weiser M, Rapp MA, Rabinowitz J, Caspi A, Schmeidler J, Knobler HY, Lubin G, Nahon D, Harvey PD, Davidson M. Arch. Gen. Psychiatry 2005; 62(12): 1297-1304.

Affiliation

Department of Psychiatry, Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, NY 10029, USA. avi.reichenberg@mssm.edu

Copyright

(Copyright © 2005, American Medical Association)

DOI

10.1001/archpsyc.62.12.1297

PMID

16330717

Abstract

CONTEXT: Consistent evidence indicates that some, but not most, patients with schizophrenia have below-average intelligence years before they manifest psychosis. However, it is not clear whether this below-average premorbid intelligence is stable or progressive. OBJECTIVE: To examine whether increased risk for schizophrenia is associated with declining intellectual performance from childhood through adolescence. DESIGN: Historical cohort study of an entire population using record linkage for psychiatric hospitalization during an 8- to 17-year follow-up period. SETTING: Mandatory assessment by the draft board of Israeli conscripts. PARTICIPANTS: Population-based cohort of 555 326 adolescents born in Israel. Data were available on 4 intelligence subtests as well as on reading and spelling abilities and on behavioral and psychosocial variables. A regression-based approach was used to assess the discrepancy between actual IQ at age 17 years and estimated IQ during childhood based on reading and spelling abilities. MAIN OUTCOME MEASURES: Hospitalization for schizophrenia (as per the International Statistical Classification of Diseases, 10th Revision criteria). RESULTS: Lower-than-expected IQ at age 17 years was associated with increased risk for later hospitalization for schizophrenia. Results were held after controlling for potential confounders. For 75% of patients with schizophrenia with low actual IQ (<85) at age 17 years and for 23% of patients with actual IQ within the normal range (> or =85), actual IQ was 10 or more points lower than expected. Lower-than-expected IQ was not associated with bipolar disorder or with depression or anxiety disorder. CONCLUSIONS: Indirect evidence suggests that intellectual deterioration from childhood through adolescence is associated with increased risk for schizophrenia. Despite within-normal-range premorbid IQ scores, apparently healthy adolescents who will later manifest schizophrenia nevertheless have intellectual decline.

Language: en