Haiyan Xu

Publications (2)13.03 Total impact

• Source

  Available from: psyonline.com.br

  Article: DRD2 C957T polymorphism interacts with the COMT Val158Met polymorphism in human working memory ability.

  Haiyan Xu, Christoph B Kellendonk, Eleanor H Simpson, John G Keilp, Gerard E Bruder, H Jonathan Polan, Eric R Kandel, T Conrad Gilliam
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  ABSTRACT: The C957T polymorphism in the dopamine D2 receptor (DRD2) gene and the Val158Met polymorphism in the Catechol-O-Methyl-Transferase (COMT) gene affect dopamine transmission and have been found to be associated with schizophrenia. Since DRD2 in mice and the COMT gene in humans modulate working memory, we examined the relationship and possible interaction of both polymorphisms to working memory performance in 188 healthy adults. Subjects having the DRD2 C/C allele showed the poorest performance in a word serial position test. Moreover, the effect of the C957T genotype was strengthened when interaction with the COMT Val158Met polymorphism was included in the analysis. We propose that an interaction of the DRD2 C957T and COMT Val158Met may be involved in the generation of some working memory deficits in schizophrenia.
  Schizophrenia Research 03/2007; 90(1-3):104-7. · 4.75 Impact Factor
• Source

  Available from: columbia.edu

  Article: Catechol-O-methyltransferase (COMT) genotypes and working memory: associations with differing cognitive operations.

  Gerard E Bruder, John G Keilp, Haiyan Xu, Marina Shikhman, Efrat Schori, Jack M Gorman, T Conrad Gilliam
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  ABSTRACT: Catechol-O-methyltransferase (COMT) is a strong candidate gene for schizophrenia and cognitive functions disrupted in this disorder. This report examines the relation of COMT genotypes to performance on a battery of working memory tests differing in the cognitive operations to be performed on the material. A large sample of 402 healthy adults were tested on four working memory tests: Spatial Delayed Response (SDR), Word Serial Position Test (WSPT), N-back, and Letter-Number Sequencing. A subsample (n = 246) was tested on the Wisconsin Card Sorting Test (WCST). A saliva swab was used to obtain DNA from all participants. Letter-Number Sequencing, which requires both storage and manipulation of information, was the only working memory test that showed expected differences among COMT genotypes, with the met/met group showing the best performance and the val/val group the poorest performance. As in previous studies, the met/met group also performed better than the val/val group on the WCST. COMT genotypes were not associated with performance on tests measuring simple storage, maintenance of temporal order or updating of information in working memory. Genotype differences in Letter-Number Sequencing and WCST suggest that higher-order components of processing (e.g., mental manipulation) are more closely related to this gene.
  Biological Psychiatry 01/2006; 58(11):901-7. · 8.28 Impact Factor