May 30, 2005

Childhood schizophrenia and IQ

IQ stabilization in childhood-onset schizophrenia
Gochman PA, Greenstein D, Sporn A, Gogtay N, Keller B, Shaw P, Rapoport JL.

Childhood onset schizophrenia (COS) is rare, but occurs in children who show symptoms of schizophrenia prior to the age of 13. This illness is usually associated with severe and persistent psychotic symptoms and there is increased brain loss (in gray matter). In this study, the researchers wanted to see what happens to IQ in the long term for children with COS.

Starting from 1990, they recruited children with COS to participate in this prospective, longitudinal study. They included 70 children with COS and gave them age appropriate intelligence tests at 2 year intervals and continued after age 18. For a subgroup of the children, they had pre-psychotic and post-psychotic IQ test results since this was a study approved by the institutional review board of the National Institute of Mental Health (NIMH). They used a statistical analysis known as mixed model regression to analyze the results.

They found that there was no progressive decline in IQ seen up to 13+ years after psychosis onset. Similar to what is found in adults with schizophrenia, for the subgroup of subjects with pre-illness scores, there was an initial steep decline in IQ, from about 2 years prior to 1.7 years after onset of psychotic symptoms. This means that the long-term trajectory of IQ measures in COS looks to be relatively stable, and cognitive functioning extends up to 13+ years after psychosis onset, in spite of chronic illness and progressive loss in brain matter.

These authors argue that this pattern of a plateau in IQ despite persisting psychotic symptoms and substantial gray matter loss argues against a neurodegenerative model of schizophrenia for COS especially since they found improvements on certain subtests of IQ. In particular, they found small but significant improvement in Comprehension (verbal understanding general principles and social situations) and Picture Arrangement (perceptual reasoning/organizational skills) subtests of IQ – which look to be areas of relative strength that teachers and family can focus on improving. However, some limitations of this study include retrospective determination of illness and the possible role of different medications on IQ.

This study was run by the Child Psychiatry Branch at the National Institute of Mental Health.

Click here to find the research summary on PubMed

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The fact that IQ drop stabilizes makes me think that the stabilization is due to the symptoms stabilizing, and not loss of grey matter. In other words, I think that the symptoms like distraction due to hearing voices and difficulty understanding the question are the main factors responsible for the drop in IQ.

Posted by: DoYouKnow at June 12, 2005 10:32 PM

still i want in details why schzophrenic pateints have low IQ scores?

please help me

Posted by: almamari at July 18, 2006 01:34 AM

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