Case Control Study
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World J Psychiatr. Jun 22, 2014; 4(2): 42-48
Published online Jun 22, 2014. doi: 10.5498/wjp.v4.i2.42
Cognitive inflexibility in Japanese adolescents and adults with autism spectrum disorders
Yuka Yasuda, Ryota Hashimoto, Kazutaka Ohi, Hidenaga Yamamori, Michiko Fujimoto, Satomi Umeda-Yano, Haruo Fujino, Masatoshi Takeda
Yuka Yasuda, Kazutaka Ohi, Michiko Fujimoto, Masatoshi Takeda, Department of Psychiatry, Osaka University Graduate School of Medicine, Osaka 5650871, Japan
Ryota Hashimoto, Molecular Research Center for Children’s Mental Development, United Graduate School of Child Development, Osaka University, Osaka 5650871, Japan
Ryota Hashimoto, Hidenaga Yamamori, 2nd Department of Psychiatry, Osaka University Graduate School of Medicine, Osaka 5650871, Japan
Hidenaga Yamamori, Satomi Umeda-Yano, Department of Molecular Neuropsychiatry, Osaka University Graduate School of Medicine, Osaka 5650871, Japan
Haruo Fujino, Graduate School of Human Sciences, Osaka University, Osaka 5650871, Japan
Author contributions: Yasuda Y was critically involved in the data collection and analysis, wrote the first draft of the manuscript, and contributed intellectually to the interpretation of the data; Hahimoto R supervised the entire project, collected the data, wrote the manuscript, was critically involved in the design of the project and was responsible for performing the literature review; all authors were critically involved in the data collection and helped to edit the manuscript.
Supported by Research grants from the Japanese Ministry of Health, Labor and Welfare, No. H22-seishin-ippan-001; the Japan Society for the Promotion of Science (JSPS) through a Grant-in-Aid for Scientific Research, No. 22390225, No. 25293250 and No. 24591680; Challenging Exploratory Research, No. 23659565; the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) through a Grant-in-Aid for Scientific Research on Innovative Areas (Comprehensive Brain Science Network), No. 25129704; Priority Areas-Research on the Pathomechanisms of Brain Disorders, No. 18023045; and the Japan Foundation for Neuroscience and Mental Health
Correspondence to: Ryota Hashimoto, MD, PhD, Associate Professor, Molecular Research Center for Children’s Mental Development, United Graduate School of Child Development, Osaka University, D3, 2-2, Yamadaoka, Suita, Osaka 5650871, Japan. hashimor@psy.med.osaka-u.ac.jp
Telephone: +81-6-68793074 Fax: +81-6-68793074
Received: November 22, 2013
Revised: February 17, 2014
Accepted: April 11, 2014
Published online: June 22, 2014
Abstract

AIM: To investigate executive function in Japanese adolescents and adults with autism spectrum disorders (ASD) compared to Japanese controls.

METHODS: Thirty-three individuals with ASD and 33 controls participated. The ASD and control groups’ demographic variables were matched for gender (male/female: 20/13 vs 20/13), age (26.1 ± 11.5 vs 26.8 ± 9.6), years of education (13.2 ± 2.9 vs 14.2 ± 1.9), full-scale intelligence quotient (IQ) (103.0 ± 16.7 vs 103.7 ± 14.7), performance IQ (96.2 ± 16.1 vs 97.8 ± 15.0), and verbal IQ (107.9 ± 16.3 vs 107.7 ± 14.4). Participants performed the Wisconsin Card Sorting Test (WCST), which assesses the executive processes involved in problem solving and cognitive flexibility, and the Continuous Performance Test (CPT), which assesses attention and impulsivity. Symptoms were assessed by the Autism-Spectrum Quotient Japanese version (AQ-J). First, we compared the scores of the WCST between the groups using a Mann-Whitney U-test and conducted an analysis of covariance for the variables with the scores of category archives and CPT scores as covariates. Second, we analyzed the correlation between the scores of the WCST and the AQ-J in the ASD group using Pearson’s r.

RESULTS: The total errors (TE) and the percentages of perseverative errors of the Milner type (%PEM) and Nelson type (%PEN) among the TE in the ASD group were significantly worse compared with the control group (ASD vs Control, respectively: TE: 16.0 ± 6.2 vs 12.6 ± 3.5, P = 0.012; %PEM: 11.7 ± 10.7 vs 6.6 ± 8.9, P = 0.037; %PEN: 20.1 ± 14.5 vs 8.7 ± 10.4, P = 0.0011). In contrast, no significant difference was observed between the two groups in the scores of categories achieved on the WCST or the CPT. An analysis of covariance revealed significant differences between the groups in the %PEN scores (P = 0.0062) but not in the TE or the %PEM scores. These results suggest that Japanese adolescents and adults with ASD have cognitive inflexibility. Furthermore, our results suggest that Japanese adolescents and adults with ASD may have difficulties using negative feedback because perseverative errors of the Nelson type indicate persistence in choosing the incorrect reaction. By contrast, there was no significant correlation between the WCST and AQ-J scores.

CONCLUSION: We confirmed the presence of cognitive inflexibility in Japanese adolescents and adults with ASD. Our results also indicated that subjects with ASD may not use negative feedback effectively.

Keywords: Executive function, Autism spectrum disorders, Perseverative errors of Nelson type, Negative feedback, Wisconsin Card Sorting Test

Core tip: We investigated executive function (EF) in Japanese adolescents and adults with autism spectrum disorders (ASD) compared to strictly matched controls. EF was assessed using the Wisconsin Card Sorting Test. To exclude confounding factors, the participants were matched for gender, age, years of education, full-scale intelligence quotient (IQ), performance IQ, verbal IQ, and attention level. Symptoms were assessed by the Autism-Spectrum Quotient Japanese version. We confirm that Japanese adolescents and adults with ASD have cognitive inflexibility, as suggested by previous findings. Furthermore, the present study results also indicate that subjects with ASD may not use negative feedback effectively.