Autism Spectrum Disorder

Hill, E.L. (2004). Executive dysfunction in autism. TRENDS in Cognitive Sciences, 8(1), 26-32.

Executive functioning skills can include a wide range of abilities including planning, sequencing, organizing, memory, initiation, and inhibition. Executive functioning skills are something all of us use on a daily basis, often throughout the entire day. There has been considerable research over the years on executive dysfunction and disorders such as ADHD, Tourette's, OCD, Schizophrenia, and ASD. Executive dysfunction is one of three existing cognitive theories for ASD, along with Theory of Mind deficits, and weak central cohesion. While it is still unclear what role all of these theories play in the development of ASD, it is clear that children with ASD exhibit challenges with planning, flexibility, and inhibition the focus for this review.

Studies suggest that individuals with ASD demonstrate consistent impairments with planning throughout the lifespan. In terms of flexibility, individuals with ASD demonstrate some form of perseveration or stereotypical movement, have difficulty with transition, and thrive in a routine environment. The review notes that studies consistently demonstrate this deficit across the lifespan and across cultures on various test measures. In terms of inhibition, children with ASD test in the typical range (unlike those with ASD) for the classic Stroop test. However, individuals with ASD may have difficulty with tests that require social interaction or appear to be irrational and arbitrary. The author notes that it is difficult to say if the deficit is related to inhibition or another deficit of ASD such as social communication or routine oriented behaviors.

Other considerations reviewed in this article relate to consistency across the lifespan, including connections to joint attention, and neuroanatomy, such as studies into prefrontal cortex changes. The link between executive dysfunction and joint attention may provide the most promising information, especially in terms of very young children. The author notes that longitudinal neuroanatomy studies in executive dysfunction and individuals with ASD across the lifespan is clearly an area of future study. Finally, the review concludes with questions about the universality of executive dysfunction in those with ASD and whether or not it can be used as a diagnostic tool. Executive dysfunction is not specific only to ASD, as it can be found in those with brain injuries, ADHD, Tourette's, OCD, Schizoprenia, and others. However, the authors of the review suggest that with further study, a particular pattern of executive dysfunction might be found. The authors also note that the universality of executive dysfunction in ASD cannot be ruled out and that further study is warranted.

Lane, A.E., Young, R.L., Baker, A.E.Z, & Angley, M.T. (2010). Sensory processing subtypes in autism: Association with adaptive behavior. Journal of Autism and Developmental Disorders, 40, 112-122.

Sensory dysfunction in those with ASD has been noted by parents and professionals, both anecdotally and clinically, for many years. With the publication of the DSM-5 and the inclusion of sensory dysfunction as part of the diagnostic criteria, it is important to understand more about the nature of sensory processing and how it might affect an individual's behavior and quality of life. This study, released before the implemented changes in the DSM-5, attempts to connect the various types of sensory processing dysfunction with particular types of adaptive behavior. Using a model-based cluster analysis, the authors of the study suggest that of their 54 participants, three specific patterns of sensory dysfunction emerged: Sensory-based inattentive seeking (SBIS), Sensory modulation with movement sensitivity (SMMS), and Sensory modulation with taste / smell sensitivity (SMTS).

The SBIS group displayed mostly typical sensory processing with the exception of Underresponsive / Seeks Sensation and Auditory Filtering on the Sensory Profile measure. This group had difficulty with inattention, distractibility, over-focused attention, and impulsivity. The SMMS group displayed sensory processing problems across all domains and had challenges with Movement Sensitivity and Low Energy / Weak (weak muscles, weak grasp, poor endurance.) According to the Vineland Adaptive Behavior Scales, this group had the greatest communication abilities. The SMTS group displayed sensory processing problems across all domains on the Sensory Profile except for Movement Sensitivity and Low Energy / Weak but had significant processing difficulties under Taste / Smell. This group had significantly greater communication problems than the others and scored lower on social communication than all the other groups. Of all the sensory profile areas, no matter which group, children who displayed sensory processing difficulties with Taste/Smell, Auditory Filtering, and Movement Sensitivity had more challenges with maladaptive behavior. The authors note that future study is warranted into the different subgroups of sensory processing and believe these findings support the use of sensory-based interventions for those with ASD.

Leekam, S.R., Uljarevic, M., & Prior, M.R. (2011). Restricted and repetitive behaviors in Autism Spectrum Disorders: A review of research in the last decade. Psychological Bulletin (APA), 137(4), 562-593.

This review examines the body of research from the last decade regarding restricted and repetitive behaviors (RRBs) in Autism Spectrum Disorder. While there has been a considerable increase in the study of RRBs, research on causes and triggers of these behaviors has not kept pace with other topics, such as pharmacological and behavioral interventions, according to the authors. They also note that while research into RRBs has spanned many different specialties, including developmental psychology, cognitive psychology, neurobiology, and psychiatry, there has been little research into an integrative approach that looks at all of these arenas. The authors acknowledge that over the last decade there has been improvement in understanding RRBs in terms of measurement and that RRBs can improve and change in individuals given developmental factors and intervention. However, the authors argue that such RRBs are central to ASD and have significant implications for functioning in a variety of settings, and as such, encourage future research to take a multi-disciplinary and developmental approach into early RRBs and RRBs such as routines, rituals and special interests. They also suggest that more research into examining the role of intensive early intervention programs and the prevention or reduction of RRBs is critical.