Executive Functioning in High Functioning Autism

A review of: GILBERT, S., BIRD, G., BRINDLEY, R., FRITH, C., BURGESS, P. (2008). Atypical recruitment of medial prefrontal cortex in autism spectrum disorders: An fMRI study of two executive function tasks. Neuropsychologia DOI: 10.1016/j.neuropsychologia.2008.03.025

Executive functioning is an umbrella term used in clinical neuropsychology and cognitive neurosciences to refer to a series of “higher-order” cognitive processes usually associated with frontal lobe functioning. These include planning, organizing, categorizing, response inhibition, monitoring, multitasking, etc. Research on executive functioning and autism has provided mixed results likely due to differences in the area of executive function measured. In this functional MRI study, the authors used a new test of executive function used to assess for stimulus dependent vs. stimulus independent thoughts. Stimulus dependent refers to cognitive processing (thinking) that is associated with, or dependent on, a specific stimulus that is presented. For example, I may ask you to press the b key when you see a blue square or the r key when you see a red square. For this task the stimulus dependent phase consisted of capital letters presented in alphabetical order. Once a letter was presented, the person had to press one key if the letter contained only straight lines (such as the letter A) and a different key if the letter contained curves (such as the letter B). In the stimulus independent task, the person was presented with one letter and ask to follow the same response pattern (one key if straight lines – another key if curves). However, the second letter presented was random and did not follow the alphabetical order, yet the person was asked to respond based on the next alphabetical letter. For example, assume the first letter was “C”, then the next letter presented was the letter “H” (random) yet the person was asked to respond to the next alphabetical letter starting from the first letter presented (C), thus the next response was based on the characteristics of the letter D, even though the person was seeing the letter H. This task therefore, requires the person to continue to “think” of the characteristics of the letters in alphabetical order, independent of the letters presented (which now are distractors).

In the study the authors examined 15 adults with high functioning autism and 18 typically developing adults that were matched for age (mean 38) and IQ (mean 119). The participants performed the task while undergoing a functional magnetic resonance imaging scan (fMRI). There was no difference in accuracy or response times between the groups. Both groups showed more activation of the lateral frontal and parietal cortex on the more difficult stimulus-independent task. However, the autism group had significantly more activation of specific areas of the medial prefrontal cortex during the easier stimulus dependent condition than the typically developing group (this was interpreted as failure to deactivate these areas). The authors argued that these results suggest an atypical brain organization in HFA with limited deactivation of the rostral prefrontal cortex during easier task compared to typically developing individuals. However, the equivalent performance (both groups did just as well on the task) suggests that the fMRI findings simply reflect different approaches to cognitive performance between the two groups.

Autism and Cerebellar Differences?

Study finds no differences in cerebellar volume in people with autism after controlling for macrocephaly, IQ, and age.

A review of: CLEAVINGER, H.B., BIGLER, E.D., JOHNSON, J.L., LU, J., McMAHON, W., LAINHART, J.E. (2008). Quantitative magnetic resonance image analysis of the cerebellum in macrocephalic and normocephalic children and adults with autism. Journal of the International Neuropsychological Society, 14(03) DOI: 10.1017/S1355617708080594

As I do my weekly literature search on Autism Research for Translating Autism, I noticed a number of forthcoming manuscripts about the role of the cerebellum in Autism. I will likely review some of these new studies and decided to start with Cleavinger et al (2008) MRI examination of cerebellum in children and adults with autism.

The cerebellum is located on the lower back region of the brain and traditionally it has been implicated in the integration of sensory information and the coordination of movement. However, more recent investigations have determined that the cerebellum is also active in various higher-order functions such as language, emotion, and cognition. In the past, studies looking at differences in the cerebellum of people with and without autism have provide mixed results with some showing increased volume in people with autism, while others show no difference, or decreased volume. One possible explanation for these conflicting findings is that people with autism often vary in degree of macrocephaly (large head size) which may affect the results if the samples studied included individuals with and without macrocephaly. To address this question the authors of this study examined 4 groups: a) people with autism and macrocephaly (N=13) b) people without autism and macrocephaly (N=8) c) people with autism and without macrocephaly (N=28) and c) people without autism and without macrocephaly (N=16). In general, after controlling for macrocephaly, age, and IQ, no statistically significant differences in cerebellar volume were found, although a trend was observed in that people with autism who also had macrocephaly showed smaller cerebellar volume as compared to similar macrocephalic individuals without autism. This trend is important because the ‘non-significant’ differences reported here are likely due to the small sample size and unequal group size, which affects the statistical power of the analysis (making it more difficult to show statistical significant differences even when such differences actually exist). But even if the 'non-differences' result is replicated and in fact no differences in cerebellar volume exist between these groups, does this mean that the cerebellum is not implicated in autism? Not at all. Here again I touch the issue of how we should avoid reaching conclusions that go beyond what the data tell us. These results only speak to the size of the cerebellum, suggesting no apparent morphological differences. These results however, do not speak to possible anomalies in the functioning of the cerebellum, which may or may not be present in autism.

Hospitalization of Children with Autism: Predictors and Frequency

Aggressive behaviors increase risk for hospitalization by more than 400%; more than any other variable.

A review of: Mandell, D.S. (2007). Psychiatric Hospitalization Among Children with Autism Spectrum Disorders. Journal of Autism and Developmental Disorders DOI: 10.1007/s10803-007-0481-2

In this large-scale study the authors examined the frequency and predictors of psychiatric hospitalization in children with autism spectrum disorders. The sample included 760 children and young adults with a diagnosis of autism, Asperger’s or PDD-NOS and their parents (age range of the children 5 to 21) living in Pennsylvania. 10.8% of the sample had a history of psychiatric hospitalization. A number of external factors were more common in children and young adults with ASDs. Those with a history of hospitalization were more likely to be: older, African-American, adopted, living in a single parent household, and have parents making less than 40,000 per year and without a college degree. In addition to these external factors, those with a history of hospitalization were also more likely to: have a diagnosis of Autism or Asperger’s (as opposed to PDD-NOS), display self-injurious behaviors, be aggressive towards others, display less stereotypies, and have more co-morbid diagnoses.

When examining the predictors of hospitalization a slightly different picture was noted. Each year of age was associated with a decrease in hospitalization risk (OR=.81). This sounds like it contradicts the finding reported above - that those with a history of hospitalization are more likely to be older. However, these are two different questions. At the group level, older people, likely simply by virtue of living longer, are more likely to have a history of hospitalization. However, at the individual level, the risk of hospitalization decreases with age, so that it becomes less likely in each subsequent year. Aggressive behavior towards others was the stronger predictor of hospitalization increasing the odds more than 400% (OR= 4.83). This was followed by having a co-morbid diagnosis of depression (OR = 2.48) or obsessive compulsive disorder (OR=2.35), and displaying self-injurious behaviors (OR=2.14). One parental variable were also identified. Living in a single parent home more than double the odds of being hospitalized (OR=2.54).

One of the most interesting issues addressed by this research is that it seems that there are two factors related to risk of hospitalization: factors that are directly reflective of the severity of the disorder (aggression, self-injurious behaviors, etc) and social-familial factors that are possibly unrelated to the disorder (SES, being a single parents, etc). It is possible that the effectiveness and utility of hospitalization may depend upon the underlying reasons as to why a child may be hospitalized. In addition, this data suggest that interventions targeted to reducing the rate of hospitalization among children with ASD should focus on: early treatment of aggressive and self-injurious behaviors, and providing better services and resources to families at risk for seeking hospitalization for their children.

High functioning autism vs. Asperger’s: the VIQ PIQ myth?

A review of: Spek, A.A., Scholte, E.M., Berckelaer-Onnes, I.A. (2008). Brief Report: The Use of WAIS-III in Adults with HFA and Asperger Syndrome. Journal of Autism and Developmental Disorders, 38(4), 782-787. DOI: 10.1007/s10803-007-0446-5

I have documented in previous posts that clinicians and researchers have often proposed that high functioning autism and Asperger’s present a significantly different neurocognitive profile (see here and here). The belief is that children with AS tend to have a significant discrepancy between verbal and non-verbal abilities, with relatively higher verbal functioning as compared to non-verbal skills. On the other hand, children with high functioning autism tend to have relatively equal verbal and non-verbal skills. However, recently I’ve been encountering several studies that suggest that this may not be the case. As reported in this brief yet very elegant study from the Leiden University in the Netherlands, the researchers conducted a cognitive assessment of 16 adults with high functioning autism and 27 adults with Asperger’s syndrome using the WAIS-III (the most common adult IQ assessment instrument). Diagnoses were confirmed via ADI using DSM-IV criteria to differentiate HFA vs. AS. There were no differences between the groups in verbal vs. non-verbal performance (VIQ vs. PIQ). There was no pattern of high-verbal low-non-verbal scores in the Asperger’s group, with both groups scoring in the High Average range for both verbal and non-verbal composite scales. However, one global factor scale difference was observed. Adults with high functioning autism showed a significantly lower Processing Speed as compared to other factor skills such as Verbal Comprehension, Perceptual Organization, and Freedom from Distractibility. This finding was not observed in the Asperger’s group. Despite this difference (and some additional task-specific differences I didn’t mention in this review), the general findings of this study fail to support the idea that people with high functioning autism and Asperger’s can be differentiated on the basis of relative strength and weaknesses in their verbal vs. non-verbal performance as measured by standard intellectual assessment batteries.

Challenges and needed supports: Perspectives from people with Asperger’s and other ASDs.

A review of:Muller, E., Schuler, A., Yates, G.B. (2008). Social challenges and supports from the perspective of individuals with Asperger syndrome and other autism spectrum disabilities. Autism, 12(2), 173-190. DOI: 10.1177/1362361307086664

This is an excellent example of research that makes a commendable effort to breach the gap between the Autism and research communities. This succinct study examined the reported challenges and supports needed as reported by people with Asperger’s syndrome or high functioning autism (HFA). The study included 18 people with ASDs (15 with a diagnosis of Asperger’s, 2 with HFA, and 1 with PDD-NOS). The participants were over 18 years old with normative intellectual functioning. The participants were interviewed using a semi-structured clinical interview that was created with the input from other people with ASDs, parents, and clinicians. The responses to the interviews were analyzed with a focus on two specific domains: reported positive and negative social experiences, and recommendations for effective social support services and strategies for improving social connectedness. In regards to social experiences, 6 common themes were identified: intense isolation, difficulty initiating social interactions, challenges relating to communication, longing for intimacy and social connectedness, desire to contribute to one’s community, and effort to develop greater social/self-awareness. In regards to recommendations for social support services and strategies, 4 common themes were noted: external supports (structured social activities, small groups and dyads, etc), communication supports (assistance with alternative forms of communication such as email and other web based applications, etc), self-initiated support (physical and outdoor activities, spirituality, etc), and attitudinal supports (teaching of tolerance of differences, willingness to initiate social interactions, etc). The authors discussed how these findings “counter a number of culturally reinforced stereotypes about ASDs – particularly the characterization of individuals with ASDs as socially aloof, deliberately self-isolating, affectively flat, and lacking consciousness of their social skills deficits.” It is also important to note that this study was conducted with mostly people with Asperger’s syndrome. We have discussed in the past how one possible difference noted between people with Asperger’s vs. functioning autism is in regards to a need for social connectedness. Thus, although this research is an excellent example of the type of inclusive research that is needed, I believe it is important that future research examine how social experiences and reported effective support systems may differ between people with Asperger’s and people with HFA, so that support systems can be better designed to meet the specific needs of these communities.

Executive dysfunction in Adults with ASDs.

A review of: Barnard, L., Muldoon, K., Hasan, R., O'Brien, G., Stewart, M. (2008). Profiling executive dysfunction in adults with autism and comorbid learning disability. Autism, 12(2), 125-141. DOI: 10.1177/1362361307088486


In this well designed study, the authors first reviewed the basic theory of Executive Function. Executive function (EF) refers to neurocognitive processes associated with the planning and implementation of actions. Some researchers have proposed that autism is directly linked to anomalies in EF. Deficits EF lead to difficulty in the planning and initiation of action, inhibition of inappropriate responses, and difficulty with strategy monitoring. One issue in assessing EF in children and adults with autism is that deficits in EF are also present in other developmental problems, such as learning disabilities, which are common in people with autism. In order to control for this possible confound, the authors compared 20 adults with autism and co-morbid learning disability against 23 adults with learning disability only. These two groups were matched for age and IQ. The authors compared their performance on a battery of neuropsychological tests of EF*. The authors found that although the group with autism performed consistently worse than the group with learning disabilities on all tasks, none of these differences reached statistical significance. The authors then created a composite score of different domains of EF and found significant differences between the groups. Specifically, the group with Autism had significantly lower scores on ‘working memory’ and ‘planning’. A few specific factors about this study are worth mentioning. The study was conducted with adults with intellectual impairment (Average IQ = 67), thus the findings may not generalize to people within the normative range of intellectual functioning. The sample size was also extremely small, which affects the ability to find statistically significant differences. Finally the authors discussed one interesting point regarding "causality". It is difficult, if not impossible, to understand the direction of the causal factors at play. Is executive functioning one contributing factor to autism (a possible cause), or is it simply a byproduct of other impairments related to autism (caused by)?

*For those interested in the specific tasks used, these included the: Tower of London, Mazes, the Knock and Tap task, Verbal Conflict, WCST, COWA, Non-verbal Fluency, and the WMS-III.

Gaze following in young adults with Autism.

Title:Brief Report: Young Adults with Autism Spectrum Disorder Show Normal Attention to Eye-Gaze Information—Evidence from a New Change Blindness Paradigm.
Source:Fletcher-Watson, S., Leekam, S.R., Findlay, J.M., Stanton, E.C. (2008). Brief Report: Young Adults with Autism Spectrum Disorder Show Normal Attention to Eye-Gaze Information—Evidence from a New Change Blindness Paradigm. Journal of Autism and Developmental Disorders DOI: 10.1007/s10803-008-0548-8

One of the most common features of children with autism is limited shared attention, and in particular gaze following. That is, when a typically developing child sees another person change eye direction towards a particular object or region (to the left or right) the typically developing child will usually turn "to see" what the other person is seeing. However, it is common for children with autism to have limited gaze following (not turning), which sometimes has been seen as evidence for limitations in Theory of Mind. The basic idea is that gaze following reflects an understanding that "the other person" is thinking that there is something interesting in the direction of the gaze, therefore I should turn and see what the other person is seeing (although there is controversy as to whether this is a reflexive behavior instead).

The authors of this study wanted to examine if young adults with autism have the same gaze following limitations as children. They compared a group of 36 young adults with high functioning autism or Asperger’s to a comparison group of typically developing young adults of equal IQs. The participants were shown sets of two identical pictures separated by a blank image. They were asked to identify the difference between the pictures. In some pictures the difference was simply the gaze direction of the subject presented on the pictures. Other changes included the presence or absence or eye glasses (or “spectacles” since this was a British study) or a change in a piece of clothing. Results: There was no difference between the two groups. People with Autism and those with typical development were both more accurate at identifying eye gaze than the presence of eye glasses. In addition, they were both faster in identifying eye gaze than eye glasses. What is most interesting about this study is that the presence/absence of eye glasses is more visually evident (bigger change of features on the picture) than changes in eye gaze. Yet, both groups were able to identify eye gaze faster. The results speak to the importance of eye gaze as a social signal and the tendency to direct attention to eye gaze when the eyes are visible. It seems that young adult with high functioning autism appear to have a normative attention bias towards eye gaze and can recognize it as well as typically developing young adults.

Difficulty coping with changes may lead to anxiety in adults with Autism.

Title: Levels of anxiety and sources of stress in adults with autism.
Authors: Gillott, Alinda; Standen, P. J.
Source: Journal of Intellectual Disabilities. Vol 11(4) Dec 2007, 359-370.

Almost all research in autism is done with children, so it is always great to see new studies being conducted with adults. This study compared 34 adults with autism with 20 adults with intellectual impairment only. Although the two groups were equal in their intellectual abilities, adults with autism had much higher (3 times) levels of anxiety than adults with intellectual impairment but not autism. The factor that was most highly associated with stress for the adults with autism was their inability to cope with change. That is, those adults with autism who had most difficulty coping with change were also the adults who experienced the most anxiety. This has implications for treatment focus, specially for adults experiencing significant levels of anxiety. Specifically, adults with autism who experience anxiety may benefit from treatment interventions that address their ability to cope with changes.