Publications (111) View all
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Article: Examining and interpreting the female protective effect against autistic behavior.
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ABSTRACT: Male preponderance in autistic behavioral impairment has been explained in terms of a hypothetical protective effect of female sex, yet little research has tested this hypothesis empirically. If females are protected, they should require greater etiologic load to manifest the same degree of impairment as males. The objective of this analysis was to examine whether greater familial etiologic load was associated with quantitative autistic impairments in females compared with males. Subjects included 3,842 dizygotic twin pairs from the Twins Early Development Study (TEDS) and 6,040 dizygotic twin pairs from the Child and Adolescent Twin Study of Sweden (CATSS). In both samples, we compared sibling autistic traits between female and male probands, who were identified as children scoring in the top 90th and 95th percentiles of the population autistic trait distributions. In both TEDS and CATSS, siblings of female probands above the 90th percentile had significantly more autistic impairments than the siblings of male probands above the 90th percentile. The siblings of female probands above the 90th percentile also had greater categorical recurrence risk in both TEDS and CATSS. Results were similar in probands above the 95th percentile. This finding, replicated across two nationally-representative samples, suggests that female sex protects girls from autistic impairments and that girls may require greater familial etiologic load to manifest the phenotype. It provides empirical support for the hypothesis of a female protective effect against autistic behavior and can be used to inform and interpret future gene finding efforts in autism spectrum disorders.Proceedings of the National Academy of Sciences 02/2013; · 9.68 Impact Factor -
Article: Reading Comprehension in Autism Spectrum Disorders: The Role of Oral Language and Social Functioning.
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ABSTRACT: Reading comprehension is an area of difficulty for many individuals with autism spectrum disorders (ASD). According to the Simple View of Reading, word recognition and oral language are both important determinants of reading comprehension ability. We provide a novel test of this model in 100 adolescents with ASD of varying intellectual ability. Further, we explore whether reading comprehension is additionally influenced by individual differences in social behaviour and social cognition in ASD. Adolescents with ASD aged 14-16 years completed assessments indexing word recognition, oral language, reading comprehension, social behaviour and social cognition. Regression analyses show that both word recognition and oral language explain unique variance in reading comprehension. Further, measures of social behaviour and social cognition predict reading comprehension after controlling for the variance explained by word recognition and oral language. This indicates that word recognition, oral language and social impairments may constrain reading comprehension in ASD.Journal of Autism and Childhood Schizophrenia 01/2013; 43(4):807-816. · 3.06 Impact Factor -
Article: Salient Social Cues are Prioritized in Autism Spectrum Disorders Despite Overall Decrease in Social Attention.
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ABSTRACT: Diminished social attention is often considered to be a central deficit in autism spectrum disorders (ASDs). We further investigate this hypothesis by measuring the distracting power of social and non-social stimuli in the context of a Stroop task among children with ASD and typically developing controls (TDCs). Our results show that Stroop interference increases with social versus non-social distracters in TDCs, whereas the opposite pattern occurs in ASD. Within social stimuli, however, the superiority of direct gaze previously reported in the literature did not differ between the groups. Our data thus suggest that ASD children assign less weight to social than non-social stimuli, but that within social signals, salient stimuli remain prioritized.Journal of Autism and Childhood Schizophrenia 11/2012; · 3.06 Impact Factor -
Article: The persistence and stability of psychiatric problems in adolescents with autism spectrum disorders.
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ABSTRACT: Background: Psychiatric problems are common in autism spectrum disorders (ASDs), but the reasons are poorly understood. We use a longitudinal population-representative cohort to examine for the first time the persistence of psychiatric problems and to identify risk factors for their occurrence and stability. Methods: Eighty-one 16-year olds (75 male, six female), initially seen at 12 years, were re-assessed using the parent-report Strengths and Difficulties Questionnaire (SDQ). Child, family and contextual characteristics from age 12 were tested as risk factors for psychopathology. Results: Prevalence rates varied depending on whether general population or ASD-specific SDQ cut-offs were used. While the former suggested a decrease in psychiatric problems over time, the ASD-specific cut-offs showed no significant differences. With the exception of ADHD, the ASD-specific cut-offs identified a smaller proportion of individuals as 'affected' than did the general population cut-offs. There was longitudinal domain specificity, with parent correlations ranging from 0.50 to 0.58 and teacher SDQ reports at age 12 correlating 0.33-0.53 with parent reports at 16 years. In examining the role of risk factors, lower IQ and adaptive functioning predicted higher hyperactivity and total difficulties scores. Greater emotional problems at 16 were predicted by poorer maternal mental health, family-based deprivation and lower social class. Improvement from 12 to 16 years in conduct problems was predicted by greater neighbourhood deprivation and special school attendance. Conclusions: This is the first longitudinal study of other psychiatric symptoms in ASD. Additional psychiatric problems in ASD are persistent and domain-specific from childhood to adolescence. The finding that age-related reduction in SDQ symptoms does not apply when ASD-specific cut-offs are used requires further evaluation using diagnostic measures. Only a few of the expected risk factor-psychopathology predictions expected from general population studies were found, raising the possibility that the causes of psychopathology in ASD differ from those in the general population.Journal of Child Psychology and Psychiatry 08/2012; · 4.28 Impact Factor -
Article: Severe mood problems in adolescents with autism spectrum disorder.
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ABSTRACT: Introduction: Severe mood dysregulation and problems (SMP) in otherwise typically developing youth are recognized as an important mental health problem with a distinct set of clinical features, family history and neurocognitive characteristics. SMP in people with autism spectrum disorders (ASDs) have not previously been explored. Method: We studied a longitudinal, population-based cohort of adolescents with ASD in which we collected parent-reported symptoms of SMP that included rage, low and labile mood and depressive thoughts. Ninety-one adolescents with ASD provided data at age 16 years, of whom 79 had additional data from age 12. We studied whether SMP have similar correlates to those seen in typically developing youth. Results: Severe mood problems were associated with current (parent-rated) and earlier (parent- and teacher-rated) emotional problems. The number of prior psychiatric diagnoses increased the risk of subsequent SMP. Intellectual ability and adaptive functioning did not predict to SMP. Maternal mental health problems rated at 12 and 16 years were associated with SMP. Autism severity as rated by parents was associated with SMP, but the relationship did not hold for clinician ratings of autistic symptoms or diagnosis. SMP were associated with difficulty in identifying the facial expression of surprise, but not with performance recognizing other emotions. Relationships between SMP and tests of executive function (card sort and trail making) were not significant after controlling for IQ. Conclusions: This is the first study of the behavioural and cognitive correlates of severe mood problems in ASD. As in typically developing youth, SMP in adolescents with ASD are related to other affective symptoms and maternal mental health problems. Previously reported links to deficits in emotion recognition and cognitive flexibility were not found in the current sample. Further research is warranted using categorical and validated measures of SMP.Journal of Child Psychology and Psychiatry 08/2012; 53(11):1157-1166. · 4.28 Impact Factor
