Kimberly E. Bodner

Evidence for selective inhibitory impairment in individuals with autism spectrum disorder.

OBJECTIVE The social and communicative challenges faced by individuals with autism spectrum disorder (ASD) are often compounded by additional difficulties with executive function. It remains unclear, however, to what the extent individuals with ASD experienced impairment in inhibitory control. The objective of the present study was to assess the three main subtypes of executive inhibitory control within a single ASD sample thus providing new insight into the unique ASD-related pattern of sparing and impairment observed across different aspects of inhibitory control. METHOD A sample of 28 children with ASD (mean age = 13.1 years) and a comparison group of 49 neurologically uncompromised children (mean age = 13.3 years) participated. A prepotent response inhibition task, a flanker visual filtering task, and a proactive interference memory task were used to evaluate prepotent response inhibition, resistance to distracter interference, and resistance to proactive interference, respectively. RESULTS After accounting for individual differences in noninhibition abilities (e.g., processing speed) and overall level of functioning, there was no evidence of group-related differences in inhibitory performance on the prepotent response inhibition test or proactive interference test. ASD-related impairments in inhibitory control were evident, however, on the flanker visual filtering task. CONCLUSIONS Taken together, the present findings indicate that ASD is associated with impairments in some, but not all, aspects of inhibitory control. Individuals with ASD appear to have difficulty ignoring distracting visual information, but prepotent response inhibition and resistance to proactive interference are relatively intact. The current findings also provide support for a multitype model of inhibitory control.

Dorsolateral prefrontal cortex magnetic resonance imaging measurements and cognitive performance in autism.

This study examined the relationships between volumetric measurements of frontal lobe structures and performance on executive function tasks in individuals with autism. Magnetic resonance imaging (MRI) scans were obtained from 38 individuals with autism and 40 matched controls between the ages of 8 and 45 years. Executive function was assessed using neuropsychological measures including the Wisconsin Card Sorting Test and Tower of Hanoi. Differences in performance on the neuropsychological tests were found between the 2 groups. However, no differences in dorsolateral prefrontal cortex volumes were observed between groups. No correlations between volumetric measurements and performance on the neuropsychological tests were found. Findings from this study suggest that executive function deficits observed in autism are related to functional but not anatomical abnormalities of the frontal lobe. The absence of correlations suggests that executive dysfunction is not the result of focal brain alterations but, rather, is the result of a distributed neural network dysfunction.

Noradrenergic moderation of working memory impairments in adults with autism spectrum disorder.

In addition to having difficulties with social communications, individuals with an autism spectrum disorder (ASD) often also experience impairment in higher-order, executive skills. The present study examined the effects of pharmacological modulation of the norepinephrine system on the severity of such impairments. A sample of 14 high-functioning adults with ASD and a demographically-matched comparison group of 13 typically developing individuals participated. An AX continuous performance test (AX-CPT) was used to evaluate working memory and inhibitory control. AX-CPT performance was assessed following administration of a single dose of propranolol (a beta adrenergic antagonist) and following placebo (sugar pill) administration. Individuals with ASD performed more poorly than non-ASD individuals in the working memory condition (BX trials). Importantly, administration of propranolol attenuated this impairment, with the ASD group performing significantly better in the propranolol condition than the placebo condition. Working memory performance of the non-ASD group was unaffected by propranolol/placebo administration. No group or medication effects were observed for the inhibition condition (AY trials). The present findings suggest that norepinephrine may play a role in some, but not necessarily all, cognitive impairments associated with ASD. Additional research is needed to fully understand whether this role is primarily causal or compensatory in nature.

Local vs. global approaches to reproducing the Rey Osterrieth complex figure by children, adolescents, and adults with high‐functioning autism

Individuals with autism have an atypical pattern of visual processing. Various studies have provided evidence that individuals with autism perceive the details of stimuli before the gestalt, the reverse of the typical pattern of visual processing. This study used the Rey Osterreith Complex Figure (ROCF) task and an objective scoring system to examine local/global processing approaches to its reproduction in 37 individuals diagnosed with high‐functioning autism (HFA) compared to 49 age‐, IQ‐, and gender‐matched typically developing controls (TD). The sample was divided into children (aged 8–14 years) and adolescents/adults (aged 15–47 years) to assess age effects. Results showed no difference in overall performance on the ROCF between HFA and TD children. TD participants displayed improved organizational and planning skills with age and a shift to global processing approaches, but there were no differences in performance between children and adolescents/adults with HFA. There was no evidence of enhanced local processing in either HFA group. These findings suggest that HFA individuals with average IQ scores do not have the clinically demonstrable evidence of the enhanced local processing thought to reflect increased local brain connectivity in more severely autistic individuals. The deficient global processing of the HFA adults reflects dependence of performance on impaired strategic problem‐solving abilities, which has been demonstrated to result from under development of neural connectivity between visuo‐spatial and frontal brain regions in HFA adults.

Effect of Propranolol on Word Fluency in Autism

Objective and BackgroundAutism is characterized by repetitive behaviors and impaired socialization and communication. Preliminary evidence showed possible language benefits in autism from the &bgr;-adrenergic antagonist propranolol. Earlier studies in other populations suggested propranolol might benefit performance on tasks involving a search of semantic and associative networks under certain conditions. Therefore, we wished to determine whether this benefit of propranolol includes an effect on semantic fluency in autism. MethodsA sample of 14 high-functioning adolescent and adult participants with autism and 14 matched controls were given letter and category word fluency tasks on 2 separate testing sessions; 1 test was given 60 minutes after the administration of 40 mg propranolol orally, and 1 test was given after placebo, administered in a double-blinded, counterbalanced manner. ResultsParticipants with autism were significantly impaired compared with controls on both fluency tasks. Propranolol significantly improved performance on category fluency, but not letter fluency among autism participants. No drug effect was observed among controls. Expected drug effects on heart rate and blood pressure were observed in both the groups. ConclusionsResults are consistent with a selective beneficial effect of propranolol on flexibility of access to semantic and associative networks in autism, with no observed effect on phonological networks. Further study will be necessary to understand potential clinical implications of this finding.

Ethical Principles and Standards That Inform Educational Gatekeeping Practices in Psychology

Educational gatekeeping functions in psychology serve to assess, remediate, and/or dismiss students and trainees with problematic professional competencies (STPPC). Recently, professional psychology graduate programs have increasingly focused on problems with professional competency, and they have begun to implement formal procedures to intervene with STPPC (Rubin et al., 2007). However, there has been considerably less literature addressing the ethics and ethical considerations of instituting these gatekeeping functions, especially in different stages of education and training in psychology. The American Psychological Association (APA; 2002) Ethical Principles of Psychologists and Code of Conduct (Ethics Code) offers faculty and supervisors ethical principles and obligatory standards that provide guidance about how to implement highly ethical gatekeeping practices. The purpose of this article is to highlight the major ethical issues and dilemmas that faculty and supervisors may face when intervening with STPPC and provide recommendations for ethical gatekeeping practices that are inspired by the APA Ethics Code.

Making inferences: Comprehension of physical causality, intentionality, and emotions in discourse by high-functioning older children, adolescents, and adults with autism

Studies investigating inferential reasoning in autism spectrum disorder (ASD) have focused on the ability to make socially-related inferences or inferences more generally. Important variables for intervention planning such as whether inferences depend on physical experiences or the nature of social information have received less consideration. A measure of bridging inferences of physical causation, mental states, and emotional states was administered to older children, adolescents, and adults with and without ASD. The ASD group had more difficulty making inferences, particularly related to emotional understanding. Results suggest that individuals with ASD may not have the stored experiential knowledge that specific inferences depend upon or have difficulties accessing relevant experiences due to linguistic limitations. Further research is needed to tease these elements apart.

Effect of propranolol on facial scanning in autism spectrum disorder: A preliminary investigation

Background: Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by social communication impairments and restricted, repetitive behaviors. Whereas current pharmacological interventions for ASD focus primarily on psychiatric symptoms, including agitation and obsessive behaviors, few agents target core symptomatology. It has been previously hypothesized that abnormalities in facial scanning, such as reduced eye contact or increased mouth fixation, contribute to social communication deficits in ASD. In addition, previous reports have suggested elevated stress and anxiety in ASD, symptoms that are believed to impact facial scanning patterns. Objectives: The present pilot study sought to explore the effects of pharmacological intervention via propranolol, a nonselective β-adrenergic antagonist and known anxiolytic, on facial scanning in ASD. Specifically, we wished to determine whether there is an increase in eye contact and a decrease in mouth fixation with administration of propranolol. Method: A sample of 14 participants with ASD and 14 matched controls participated in two study sessions in which propranolol and placebo were administered in a counterbalanced, double-blinded manner. At each session, ocular fixation data were collected during presentation of video stimuli of 16 human faces. Fixation time on the eye, nose, and mouth regions of the face stimuli was analyzed. Results: The baseline fixation patterns for the ASD and control groups did not significantly differ; however, administration of propranolol was associated with a significant reduction in mouth fixation for the ASD group. Additionally, mouth fixation was positively related to nonverbal communication impairment in the ASD group. Conclusions: Although eye fixation in ASD appears typical in the present study, the effect of propranolol in reducing mouth fixation suggests an important focus for further research. Future studies are needed to better characterize the relationship between stress and anxiety and facial scanning in ASD, as well as the effects of pharmacological intervention.

A volumetric study of basal ganglia structures in individuals with early-treated phenylketonuria

Whereas the impact of early-treated phenylketonuria (ETPKU) on cortical white matter is well documented, relatively little is known regarding the potential impact of this metabolic disorder on deep gray matter structures such as the basal ganglia. The current study used high-resolution (1mm(3)) magnetic resonance imaging to investigate bilateral basal ganglia structures (i.e., putamen, caudate nucleus, and nucleus accumbens) in a sample of 13 individuals with ETPKU and a demographically-matched sample of 13 neurologically intact individuals without PKU. Consistent with previous research, we found smaller whole brain volumes in the ETPKU group compared with the non-PKU group. Individuals with ETPKU also had significantly larger putamen volumes than non-PKU individuals. In addition, the degree of putamen enlargement was correlated with blood phenylalanine levels and full scale IQ in the ETPKU group. These findings are consistent with the hypothesis that ETPKU-related increases in phenylalanine lead to decreased central dopamine levels thus impacting dopamine-dependent brain regions such as the putamen that play an important role in cognition.

Morphometric analysis of gray matter integrity in individuals with early-treated phenylketonuria

The most widely-reported neurologic finding in individuals with early-treated phenylketonuria (PKU) is abnormality in the white matter of the brain. In contrast, much less is known regarding the impact of PKU on cortical gray matter (GM) structures. Presently, we applied advanced morphometric methods to the analysis of high-resolution structural MRI images from a sample of 19 individuals with early-treated PKU and an age- and gender-matched comparison group of 22 healthy individuals without PKU. Data analysis revealed decreased GM volume in parietal cortex for the PKU group compared with the non-PKU group. A similar trend was observed for occipital GM volume. There was no evidence of group-related differences in frontal or temporal GM volume. Within the PKU group, we also found a significant relationship between blood phenylalanine levels and GM volume for select posterior cortical sub-regions. Taken together with previous research on white matter and gray matter abnormalities in PKU, the present findings point to the posterior cortices as the primary site of neurostructural changes related to early-treated PKU.