Objective: Previous research has demonstrated that the amygdala is enlarged in children with autism spectrum disorder (ASD). However, the precise onset of this enlargement during infancy, how it relates to later diagnostic behaviors, whether the timing of enlargement in infancy is specific to the amygdala, and whether it is specific to ASD (or present in other neurodevelopmental disorders, such as fragile X syndrome) are all unknown. Methods: Longitudinal MRIs were acquired at 6–24 months of age in 29 infants with fragile X syndrome, 58 infants at high likelihood for ASD who were later diagnosed with ASD, 212 high-likelihood infants not diagnosed with ASD, and 109 control infants (1,099 total scans). Results: Infants who developed ASD had typically sized amygdala volumes at 6 months, but exhibited significantly faster amygdala growth between 6 and 24 months, such that by 12 months the ASD group had significantly larger amygdala volume (Cohen’s d=0.56) compared with all other groups. Amygdala growth rate between 6 and 12 months was significantly associated with greater social deficits at 24 months when the infants were diagnosed with ASD. Infants with fragile X syndrome had a persistent and significantly enlarged caudate volume at all ages between 6 and 24 months (d=2.12), compared with all other groups, which was significantly associated with greater repetitive behaviors. Conclusions: This is the first MRI study comparing fragile X syndrome and ASD in infancy, demonstrating strikingly different patterns of brain and behavior development. Fragile X syndrome–related changes were present from 6 months of age, whereas ASD-related changes unfolded over the first 2 years of life, starting with no detectable group differences at 6 months. Increased amygdala growth rate between 6 and 12 months occurs prior to social deficits and well before diagnosis. This gradual onset of brain and behavior changes in ASD, but not fragile X syndrome, suggests an age- and disorder-specific pattern of cascading brain changes preceding autism diagnosis.
This review describes the effects of intervention for young children with autism spectrum disorder (ASD) on parents. Like all children, children with ASD bring both negative and positive experiences for parents and families-from increased resource needs, to higher levels of parenting-related stress, to positive personal growth for family members. It is increasingly recognized that, although children with ASD are the primary targets of early ASD intervention, ASD intervention also impacts parents. From the time emerging developmental concerns begin to be identified, through the process of obtaining a diagnosis and initiating services, parents play a central role in addressing the needs of young children with ASD, including implementing and supporting early intervention. Parents experience the impact of intervention directly, through interaction with providers within the health care and educational systems. Parents also experience indirect impacts of ASD intervention due to accelerated developmental progress of children who are benefitting from services and when children make slower progress than expected or have challenging behaviors. Parental stress and psychological well-being are legitimate targets of intervention and compelling research objectives, needing no additional justification. However, parents are also the major contributors to family adaptive functioning-the activities families employ to support positive outcomes for children with ASD (e.g., family-orchestrated child experiences, parent-child interaction, child health and safety functions; Guralnick, 1997). A parent's ability to carry out adaptive functions is, in part, related to their levels of stress and psychological well-being. Thus, there is a transactional process in which parents are both impacted by and have an impact on ASD interventions for their child. Evaluating the effect of ASD intervention on parents is needed to develop new strategies for helping parents and children with ASD reach their full potential. This review will provide an overview of research on the impact of early ASD intervention on parents. Evidence regarding the impact of three types of intervention (i.e., early intensive behavioral intervention, parent-implemented intervention, and programs directly targeting parent stress) on parent well-being and family adaptive functioning will be reviewed. Potential moderators of the impact of ASD intervention on parents and family adaptive functioning will be discussed. We conclude that research on the impact of ASD intervention on parents of young children with ASD is a promising avenue for improving the lives of children with ASD and their families.
Objective: There has been a steady rise in research characterizing executive functioning (EF) impairments in autistic individuals but limited research investigating EF strengths. This review provides a summary of current EF research in autistic adults with a focus on EF challenges and strengths and potential sources of heterogeneity in research findings. New avenues for addressing gaps in our understanding of EF strengths are proposed.Method: A review of the EF literature was conducted. One hundred twenty-four studies of inhibition, working memory, cognitive flexibility, fluency, planning, decision-making, and subjective measures of EF in autistic adults were included.Results: Autistic adults with average intellectual functioning demonstrate difficulties with cognitive flexibility, phonemic fluency, and working memory. Strengths in planning, decision-making, and semantic verbal fluency were evident in some but not all studies. Findings regarding inhibition are inconclusive. Key findings across each EF domain are discussed and sources of potential heterogeneity across studies were evaluated. The type of measure used appears to contribute to heterogeneous findings. Subjective EF measures revealed more consistent findings of deficits in autistic adults than objective EF measures.Conclusions: Research reveals areas of EF weaknesses as well as strengths in autistic adults. Unlike EF challenges, EF strengths are not well understood. Future research identifying EF strengths is needed to improve services and supports for autistic adults. Further investigation of potential factors that interact with or constrain EF such as comorbid disorders, verbal ability, sensory processing, and other factors specific to autism will be critical to move the field forward and increase understanding of how EF is related to everyday functioning in autistic adults.
Atypical sensory responsivity and sensory interests are now included in the DSM 5 diagnostic criteria for autism spectrum disorder (ASD) under the broad domain of restricted and repetitive behavior (RRB). However, relatively little is known about the emergence of sensory-related features and their relation to conventionally defined RRB in the first years of life.
