Pubmed du 06/06/09

lundi 8 juin 2009

1. Begeer S, Terwogt MM, Lunenburg P, Stegge H. Brief Report : Additive and Subtractive Counterfactual Reasoning of Children with High-Functioning Autism Spectrum Disorders. J Autism Dev Disord ;2009 (Jun 4)

The development of additive (’If only I had done...’) and subtractive (’If only I had not done....’) counterfactual reasoning was examined in children with High Functioning Autism Spectrum Disorders (HFASD) (n = 72) and typically developing controls (n = 71), aged 6-12 years. Children were presented four stories where they could generate counterfactuals based on a given consequent (e.g., ’you left muddy footprints in the kitchen. How could that have been prevented ?’). Children with HFASD increasingly used subtractive counterfactuals as they got older, but controls showed an increase in additive counterfactuals, which may be linked to their growing adaptive and flexible skills. Children with HFASD likely develop different strategies for their counterfactual reasoning. The role of IQ and ideational fluency will be discussed.

2. Brito AR, Vasconcelos MM, Domingues RC, Hygino da Cruz Jr LC, Rodrigues LD, Gasparetto EL, Calcada CA. Diffusion Tensor Imaging Findings in School-Aged Autistic Children. J Neuroimaging ;2009 (Mar 25)

ABSTRACT OBJECTIVE To analyze and compare cerebral white matter tracts through diffusion tensor imaging in autistic and normal children. METHODS This is a case-control study on a sample of eight male, right-handed children diagnosed with autism according to Diagnostic and Statistical Manual of Mental Disorders-4th Edition criteria, and eight healthy age- and sex-matched controls. Imaging studies were performed on a 1.5-T scanner (Symphony Maestro Class, Siemens, Erlangen, Germany). Fractional anisotropy was calculated for the frontopontine and corticospinal tracts, frontal subcortical white matter, anterior cingulate, corpus callosum, striatum, internal capsule, optic radiation, superior and inferior longitudinal fascicles, and cerebellum. Analysis of significance was based on analysis of variance test for the mean fractional anisotropy values. RESULTS Median age of cases was 9.53 +/- 1.83 years, and of controls, 9.57 +/- 1.36 years. Diffusion tensor imaging findings included significant reduction of fractional anisotropy in the anterior corpus callosum (P= .008), right corticospinal tract (P= .044), posterior limb of right and left internal capsules (P= .003 and .049, respectively), left superior cerebellar peduncle (P= .031), and right and left middle cerebellar peduncles (P= .043 and .039, respectively) in autistic children. CONCLUSIONS The diffusion tensor imaging findings in children with autistic disorder suggest impairment of white matter microstructure, possibly associated with reduced connectivity in corpus callosum, internal capsule, and superior and middle cerebellar peduncles. J Neuroimaging 2009 ;XX:1-7.

3. Cheung C, Chua SE, Cheung V, Khong PL, Tai KS, Wong TK, Ho TP, McAlonan GM. White matter fractional anisotrophy differences and correlates of diagnostic symptoms in autism. J Child Psychol Psychiatry ;2009 (Mar 28)

Background : Individuals with autism have impairments in 3 domains : communication, social interaction and repetitive behaviours. Our previous work suggested early structural and connectivity abnormalities in prefrontal-striato-temporal-cerebellar networks but it is not clear how these are linked to diagnostic indices. Method : Children with autism (IQ > 70) aged 6 to 14 years old and matched typically developing controls were studied using diffusion tensor imaging. Voxel-based methods were used to compare fractional anisotrophy (FA) measures in each group and to correlate FA measures in the autism group with the diagnostic phenotype described by the Autism Diagnostic Interview - Revised (ADI-R) algorithm for ICD-10. Results : After controlling for the effects of age and white matter volume, we found that FA in the autism group was significantly lower than controls in bilateral prefrontal and temporal regions, especially in the right ventral temporal lobe adjacent to the fusiform gyrus. FA was greater in autism in the right inferior frontal gyrus and left occipital lobe. We observed a tight correlation between lower FA and higher ADI-R diagnostic algorithm scores across white matter tracts extending from these focal regions of group difference. Communication and social reciprocity impairments correlated with lower FA throughout fronto-striato-temporal pathways. Repetitive behaviours correlated with white matter indices in more posterior brain pathways, including splenium of the corpus callosum and cerebellum. Conclusions : Our data support the position that diagnostic symptoms of autism are associated with a core disruption of white matter development.

4. Crane L, Goddard L, Pring L. Specific and general autobiographical knowledge in adults with autism spectrum disorders : The role of personal goals. Memory ;2009 (Jun 4):1-20.

5. Fan X, Miles JH, Takahashi N, Yao G. Abnormal Transient Pupillary Light Reflex in Individuals with Autism Spectrum Disorders. J Autism Dev Disord ;2009 (Jun 5)

Computerized binocular infrared pupillography was used to measure the transient pupillary light reflex (PLR) in both children with autism spectrum disorders (ASDs) and children with typical development. We found that participants with ASDs showed significantly longer PLR latency, smaller constriction amplitude and lower constriction velocity than children with typical development. The PLR latency alone can be used to discriminate the ASD group from the control group with a cross-validated success rate of 89.6%. By adding the constriction amplitude, the percentage of correct classification can be further improved to 92.5%. In addition, the right-lateralization of contraction anisocoria that was observed in participants with typical development was not observed in those with ASDs. Further studies are necessary to understand the origin and implications of these observations. It is anticipated that as potential biomarkers, these pupillary light reflex measurements will advance our understanding of neurodevelopmental differences in the autism brain.

6. Fong CB, Thong MK, Sam CK, Mohamed Noor MN, Ariffin R. MECP2 mutations in Malaysian Rett syndrome patients. Singapore Med J ;2009 (May) ;50(5):529-533.

INTRODUCTION : Rett syndrome (RS) is a severe neurodevelopmental disorder characterised by normal neurological development followed by progressive developmental regression. The X-linked dominant inheritance of RS has been mapped to the gene that encodes the methyl-CpG-binding protein-2 (MECP2) at Xq28. In the present study, denaturing high-performance liquid chromatography (DHPLC) was used to detect mutations in the MECP2 gene in 20 Malaysian RS patients. METHODS : Polymerase chain reaction (PCR) was carried out to amplify the MECP2 coding exons 2, 3, and 4 in a total of eight reactions (exons 2, 3a, 3b, 4a, 4b, 4c, 4d and 4e). Subsequently, PCR products were analysed by DHPLC. RESULTS : Mutations in the MECP2 gene were detected in 13 of the 20 (65 percent) RS patients. 11 patients had mutations in exons 3b and 4a and six patients had mutations in exon 4c. These mutations were mainly concentrated in the methyl-CpG-binding domain and the transcriptional-repression domain. CONCLUSION : Through the use of post-PCR high-performance liquid chromatography, 65 percent of 20 RS patients were found to have mutation(s) in the MECP2.

7. Greenfeld KT. How autism ages. Time ;2009 (May 25) ;173(20):32-33, 35-36.

8. Hu VW, Nguyen A, Kim KS, Steinberg ME, Sarachana T, Scully MA, Soldin SJ, Luu T, Lee NH. Gene expression profiling of lymphoblasts from autistic and nonaffected sib pairs : altered pathways in neuronal development and steroid biosynthesis. PLoS ONE ;2009 ;4(6):e5775.

Despite the identification of numerous autism susceptibility genes, the pathobiology of autism remains unknown. The present "case-control" study takes a global approach to understanding the molecular basis of autism spectrum disorders based upon large-scale gene expression profiling. DNA microarray analyses were conducted on lymphoblastoid cell lines from over 20 sib pairs in which one sibling had a diagnosis of autism and the other was not affected in order to identify biochemical and signaling pathways which are differentially regulated in cells from autistic and nonautistic siblings. Bioinformatics and gene ontological analyses of the data implicate genes which are involved in nervous system development, inflammation, and cytoskeletal organization, in addition to genes which may be relevant to gastrointestinal or other physiological symptoms often associated with autism. Moreover, the data further suggests that these processes may be modulated by cholesterol/steroid metabolism, especially at the level of androgenic hormones. Elevation of male hormones, in turn, has been suggested as a possible factor influencing susceptibility to autism, which affects approximately 4 times as many males as females. Preliminary metabolic profiling of steroid hormones in lymphoblastoid cell lines from several pairs of siblings reveals higher levels of testosterone in the autistic sibling, which is consistent with the increased expression of two genes involved in the steroidogenesis pathway. Global gene expression profiling of cultured cells from ASD probands thus serves as a window to underlying metabolic and signaling deficits that may be relevant to the pathobiology of autism.

9. Reed HE, McGrew SG, Artibee K, Surdkya K, Goldman SE, Frank K, Wang L, Malow BA. Parent-Based Sleep Education Workshops in Autism. J Child Neurol ;2009 (Jun 1)

To determine if parents can successfully teach their children with autism spectrum disorders to become better sleepers, we piloted small group parent education workshops focused on behavioral sleep strategies. Workshops consisted of three 2-hour sessions conducted over consecutive weeks by 2 physicians. Curricula included establishing effective daytime and nighttime habits, initiating a bedtime routine, and optimizing parental interactions at bedtime and during night wakings. Baseline and treatment questionnaires and actigraphy were analyzed in 20 children, ages 3 to 10 years. Improvements after treatment were seen in the total scale and several insomnia-related subscales of the Children’s Sleep Habits Questionnaire. Actigraphy documented reduced sleep latency in children presenting with sleep onset delay. Improvements were also noted in measures of sleep habits and daytime behavior. Brief parent-based behavioral sleep workshops in children with autism spectrum disorders appear effective in improving subjective and objective measures of sleep, sleep habits, and daytime behavior.

10. Schmidt GL, Rey MM, Oram Cardy JE, Roberts TP. Absence of M100 source asymmetry in autism associated with language functioning. Neuroreport ;2009 (May 30)

Various clinical populations display atypical volume asymmetry of language structures and also the auditory M100 source. Although such atypical volume asymmetries have also been observed in autism, M100 source asymmetries have not yet been investigated. We examined M100 asymmetry in autism and its relationship with language functioning. Evoked neural activity to a 1 kHz tone was recorded using whole-cortex 151-channel magnetoencephalography in three groups of individuals. A single-dipole model identified the M100 generator in auditory cortex in each hemisphere. Healthy adults and control children displayed the expected right-sided M100 anteriority, whereas children with autism showed no such asymmetry. An association was found between language functioning and the degree of asymmetry across the two groups of children, suggesting a possible relationship between functional-structural asymmetry and language ability.

11. van der Zwaag B, Franke L, Poot M, Hochstenbach R, Spierenburg HA, Vorstman JA, van Daalen E, de Jonge MV, Verbeek NE, Brilstra EH, van ’t Slot R, Ophoff RA, van Es MA, Blauw HM, Veldink JH, Buizer-Voskamp JE, Beemer FA, van den Berg LH, Wijmenga C, van Amstel HK, van Engeland H, Burbach JP, Staal WG. Gene-network analysis identifies susceptibility genes related to glycobiology in autism. PLoS ONE ;2009 ;4(5):e5324.

The recent identification of copy-number variation in the human genome has opened up new avenues for the discovery of positional candidate genes underlying complex genetic disorders, especially in the field of psychiatric disease. One major challenge that remains is pinpointing the susceptibility genes in the multitude of disease-associated loci. This challenge may be tackled by reconstruction of functional gene-networks from the genes residing in these loci. We applied this approach to autism spectrum disorder (ASD), and identified the copy-number changes in the DNA of 105 ASD patients and 267 healthy individuals with Illumina Humanhap300 Beadchips. Subsequently, we used a human reconstructed gene-network, Prioritizer, to rank candidate genes in the segmental gains and losses in our autism cohort. This analysis highlighted several candidate genes already known to be mutated in cognitive and neuropsychiatric disorders, including RAI1, BRD1, and LARGE. In addition, the LARGE gene was part of a sub-network of seven genes functioning in glycobiology, present in seven copy-number changes specifically identified in autism patients with limited co-morbidity. Three of these seven copy-number changes were de novo in the patients. In autism patients with a complex phenotype and healthy controls no such sub-network was identified. An independent systematic analysis of 13 published autism susceptibility loci supports the involvement of genes related to glycobiology as we also identified the same or similar genes from those loci. Our findings suggest that the occurrence of genomic gains and losses of genes associated with glycobiology are important contributors to the development of ASD.

12. Vital PM, Ronald A, Wallace GL, Happe F. Relationship between special abilities and autistic-like traits in a large population-based sample of 8-year-olds. J Child Psychol Psychiatry ;2009 (Mar 28)

Background : The raised incidence of special abilities or ’savant skills’ among individuals with autism spectrum disorders (ASD) relative to other developmental disorders suggests an association between the traits characteristic of ASD and special abilities. The purpose of this study was to investigate the association between special abilities and ASD-like traits. Methods : This study compared the scores of 6,426 8-year-olds with and without parent-reported special abilities on a screening questionnaire for ASD-like traits in three areas : social interaction, communication, and restricted and repetitive behaviours and interests. Measures of IQ, sex, and socioeconomic status (SES) were also compared. Results : From parent report, children with special abilities showed significantly more ASD-like traits than those without such abilities. General intelligence did not mediate this relationship : IQ was found to be positively associated with ability, but negatively associated with ASD-like traits. Special abilities were more strongly associated with restricted/repetitive characteristics than with social or communication traits. Conclusions : Results support the association between special abilities and ASD-like traits, and expand it to traits in the general population. The type of nonsocial traits most strongly associated with parental reports of special abilities suggests a link to a featural information processing style, or ’weak central coherence’.


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