Schizophrenia genetic variants are not associated with intelligence

Terwisscha van Scheltinga, A. F., Bakker, S. C., Van Haren, N. E. M., Derks, E. M., Buizer-Voskamp, J. E., Cahn, W., Ripke, S., Ophoff, R. A., Kahn, R. S., Psychiatric Genomic-Wide Association Study (GWAS) Consortium, Visscher, P. M., Mowry, B. J., Brown, M. A. and McGrath, J. J. (2013) Schizophrenia genetic variants are not associated with intelligence. Psychological Medicine, 43 12: 2563-2570. doi:10.1017/S0033291713000196

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Author Terwisscha van Scheltinga, A. F.
Bakker, S. C.
Van Haren, N. E. M.
Derks, E. M.
Buizer-Voskamp, J. E.
Cahn, W.
Ripke, S.
Ophoff, R. A.
Kahn, R. S.
Psychiatric Genomic-Wide Association Study (GWAS) Consortium
Visscher, P. M.
Mowry, B. J.
Brown, M. A.
McGrath, J. J.
Title Schizophrenia genetic variants are not associated with intelligence
Journal name Psychological Medicine   Check publisher's open access policy
ISSN 0033-2917
Publication date 2013-12-01
Sub-type Article (original research)
DOI 10.1017/S0033291713000196
Volume 43
Issue 12
Start page 2563
End page 2570
Total pages 8
Place of publication Cambridge, United Kingdom
Publisher Cambridge University Press
Language eng
Formatted abstract
Background Schizophrenia is associated with lower pre-morbid intelligence (IQ) in addition to (pre-morbid) cognitive decline. Both schizophrenia and IQ are highly heritable traits. Therefore, we hypothesized that genetic variants associated with schizophrenia, including copy number variants (CNVs) and a polygenic schizophrenia (risk) score (PSS), may influence intelligence.

Method IQ was estimated with the Wechsler Adult Intelligence Scale (WAIS). CNVs were determined from single nucleotide polymorphism (SNP) data using the QuantiSNP and PennCNV algorithms. For the PSS, odds ratios for genome-wide SNP data were calculated in a sample collected by the Psychiatric Genome-Wide Association Study (GWAS) Consortium (8690 schizophrenia patients and 11 831 controls). These were used to calculate individual PSSs in our independent sample of 350 schizophrenia patients and 322 healthy controls.

Results Although significantly more genes were disrupted by deletions in schizophrenia patients compared to controls (p = 0.009), there was no effect of CNV measures on IQ. The PSS was associated with disease status (R2 = 0.055, p = 2.1 × 10−7) and with IQ in the entire sample (R2 = 0.018, p = 0.0008) but the effect on IQ disappeared after correction for disease status.

Conclusions Our data suggest that rare and common schizophrenia-associated variants do not explain the variation in IQ in healthy subjects or in schizophrenia patients. Thus, reductions in IQ in schizophrenia patients may be secondary to other processes related to schizophrenia risk.
Keyword Cognition
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Queensland Brain Institute Publications
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UQ Diamantina Institute Publications
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Citation counts: TR Web of Science Citation Count  Cited 15 times in Thomson Reuters Web of Science Article | Citations
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Created: Sat, 22 Feb 2014, 00:32:35 EST by Debra McMurtrie on behalf of Queensland Brain Institute