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Environmental Influences and Neurocognitive Profile in Autism Spectrum Disorders: A Discordant Monozygotic Twin Pairs Design

Friday, 3 May 2013: 14:00-18:00
Banquet Hall (Kursaal Centre)
C. Willfors1, S. Berggren1, P. Lichtenstein2, H. Anckarsäter3 and S. Bölte1, (1)Department of Women's and Children's Health, Astrid Lindgren Children's Hospital, Q2:07, Center of Neurodevelopmental Disorders (KIND), Karolinska Institutet, Stockholm, Sweden, (2)Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden, (3)Department of Forensic Psychiatry, Institute of Neuroscience and Physiology, Sahlgren’s Academy, University of Gothenburg, Gothenburg, Sweden
Background: The cognitive phenotype of Autism Spectrum Disorders (ASDs) is characterized by a detail-focused processing style. Current research suggests both hypo connectivity and enhanced perceptual functioning to account for piecemeal processing in ASD. The study of monozygotic (MZ) twin pairs discordant for ASD phenotype appears to be a promising lead to further examine the genetic and environmental origins of cognitive alterations in ASD.

Objectives: As a part of the Roots of Autism Twin Study Sweden (“RATSS”), to examine whether i) twins with ASD and broader ASD phenotypes show increased attention to detail, as compared to typical developed twins, and ii) whether co-twins with ASD or broader ASD phenotypes present with increased attention to detail compared to their co-twins being qualitatively or quantitatively discordant for ASD or ASD traits. 

Methods: In RATSS, performance in visual attention to detail is assessed with the Embedded Figures Test (EFT; child/adult version) and the Fragmented Picture Test (FPT). Seven twin pairs discordant for ASD and 11 typically developing twin pairs were included in this study. In the group of twins being discordant for ASD (N=14), the male/female ratio was 12:2, and Wechsler IQs ranged from 65 to 115 (Md=92). In the group of typically developing twins (N=22), the male/female ratio was 8:14, with an IQ range of 81 to 126 (Md=100). Mann-Whitney U and Wilcoxon Signed Rank tests were used to compare between- and within-pair scores, respectively.

Results: Between-pair analyses for FPT scores showed a trend for typically developing twin pairs to outperform ASD individuals on the FPT tasks (Z=1.661; p=.051). Consistently, within-pair analyses indicated a trend for unaffected or less affected co-twins to show superior performance on the FPT in comparison with their ASD or broader phenotype co-twin (Z=1.364; p=.086). The same statistical analyses showed no differences neither between the pairs nor in the pairs for EFT scores (p>.1).  

Conclusions: These preliminary data indicate a link between ASD/ASD traits and visual attention to detail. The link might be influenced by non-shared environmental factors.

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