Neurocognitive & Electrophysiological Phenotypes and Genetic Risk of Autism Spectrum Disorders
Date Issued
2015
Date
2015
Author(s)
Chien, Yi-Ling
Abstract
Autism spectrum disorders (ASD) are a group of severe, multi-factorial, life-long impairing childhood-onset neurodevelopmental disorders that begin in the first 2 years and throught the entire life. Although the high prevalence and high psychosocial impact of the illness, the research of its etiology faces critical stagnation and the effect of treatment nowadays seems far from satisfaction. Clinical and etiological heterogeneity composes of the most important challenges. This study aims to investigate (1) the neurocognitive and sensory phenotypes beyond the core symptoms of ASD; (2) electrophysological response in response to auditory and thermsl stimuli; (3) prenatal/perinatal risk factors and genetic risks. Compared to typically developing controls (TD), youths with ASD showed more severe attention deficits, hyperactive/impulsive symptoms, and oppositinal defiant behaviors, with more severe oppositional defiant behaviors in Asperger’s disorder than autistic disorder. Around 65.6% patients with autistic disorder and 79.3% patients with Asperger’s disorder fulfilled the diagnosis of attention deficit hyperacitivty disorder. Combined type was higher than inattentive type and hyperactive/impulsive type. In Connors’ Continuous Performance Test, both autistic disorder and Asperger’s disorder revealed focused attention and sustained attention deficits, while youths with autistic disorder had more impairment in focused attention and youths with Asperger’s disorder had poorer sustained attention. In visual memory tasks, youths with ASD had a wide range of visual memory impairments that were moderated by age and IQ, in support with temporal and frontal lobe dysfunction in ASD. Memory loading of the tasks, and involvement of spatial working memory may also influence the visual memory performance. Young adults with ASD demonstrated more sensory symptoms in daily life, including lower registration, more sensory sensitivity and sensory avoiding, while fewer sensation seeking behviors. In response to duration deviant auditory stimuli, individuals with ASD showed a shorter P3a peak latency; this parameter was associated with social awareness deficits in ASD. Besides, P3a peak amplitude to frequency deviant stimuli was correlated with sensory avoiding and patterns preoccupation in TD, while P3a peak latency may reflect sensory avoiding and attention to details in ASD. Combined duration and frequency P3a latency, as well as sensory sensitivity and sensation seeking, ASD could be differentiated from TD. In contact heat evoked potentails (CHEP), individuals with ASD had attenuated CHEP response to thermal stimuli, which were correlated with self-reported sensory and autistic symptoms, indicated that CHEP parameters are potential trait markers for perceptual disturbance in individuals with ASD. Reported pain in ASD was similar to that in TD, and was predicted by N2 peak latency, overall autistic symptom severity, and low registration. N2 latency can also predict sensory sensitivity and social emotion problems. Pre-/perinatal complications occurred more frequently in both ASD probands and their unaffected siblings compared to TD controls. Probands with ASD had a higher number of complications than siblings, which may be associated with more severe autistic symptoms. The presence of some factors was associated with more severe overall autistic symptoms and/or stereotyped behaviors, suggesting a role of pre-/perinatal factor in moderating phenotype expression of ASD. The WNT2 haplotype and DRB1 genotype were not only associated with autism diagnosis but also associated with autistic symptoms and neuropsychological function respectively. The mechanisms of the pathogenesis of ASD warrant further research.
Subjects
autism spectrum disorders
attention deficits
visual memory
sensory symptoms
event-related potentials
prenatal/perinatal risk factors
genetic association
SDGs
Type
thesis
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