Premorbid IQ as a predictor for the course of IQ in first onset patients with schizophrenia: a 10-year follow-up study.

Full Abstract

The aim of the present study was to examine the longitudinal course of IQ and its heterogeneity in patients with schizophrenia, from the perspective of the two main "subtypes" of schizophrenia described in the literature:
progressive cognitive deficit versus cognitive stabilisation or recovery. Premorbid IQ scores and WAIS IQ scores of 100 first onset patients were obtained at first hospitalization (T1) and after 10 years (T2). Significant changes in IQ over time were found, representing (i) at T1, a deterioration compared to premorbid intelligence (B=-6.3, 95% CI -9.5 to -3.0, p<0.0001), followed by (ii) a recovery at T2 where IQ matched premorbid intelligence again (B=0.5, 95% CI -3.1 to 4.0, p=0.79). In addition, a significant interaction was found between course of IQ over time and estimated premorbid IQ, demonstrating that subjects with lower premorbid IQ levels remained stable over time whereas in individuals with higher premorbid IQ levels a pattern of deterioration was evident at T1, followed by a recovery up to premorbid level at T2. The data confirm the importance of estimated premorbid IQ as an indicator of the longitudinal course of cognitive functioning in patients with schizophrenia and add evidence to the hypothesis of heterogeneity or "subtypes" of schizophrenia. The data, however, do not confirm the existence of progressive deterioration of cognitive functioning. Rather, catching up of cognitive function later in the course of the illness may take place in those whose deficits become apparent in the early phases of illness, whereas those with the most severe premorbid impairments remain stable.

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Author information

Author/s: van Winkel, Ruud (R); Myin-Germeys, Inez (I); Delespaul, Philippe (P); Peuskens, Jozef (J); De Hert, Marc (M); van Os, Jim (J);

Affiliation: University Psychiatric Center Katholieke Universiteit Leuven, Leuvensesteenweg 517, 3070 Kortenberg, Belgium. ruud.van.winkel(-atsign-)uc-kortenberg.be

Journal and publication information

Publication Type: Journal Article; Research Support, Non-U.S. Gov't

Journal: Schizophrenia research (Schizophr Res), published in Netherlands. (Language: eng)

Reference: 2006-Dec; vol 88 (issue 1-3) : pp 47-54

Dates: Created 2006/11/13; Completed 2007/02/06;

PMID: 16904292, status: MEDLINE (last retrieval date: 12/26/2008)

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Adult
Cognition Disorders - diagnosis; etiology
Female
Follow-Up Studies
Humans
Intelligence

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