“Leaky Gut” revisited: Intestinal problems in children with autism.

Title: Intestinal Permeability and Glucagon-like peptide-2 in Children with Autism: A Controlled Pilot Study.
Source:Robertson, M.A., Sigalet, D.L., Holst, J.J., Meddings, J.B., Wood, J., Sharkey, K.A. (2008). Intestinal Permeability and Glucagon-like peptide-2 in Children with Autism: A Controlled Pilot Study. Journal of Autism and Developmental Disorders DOI: 10.1007/s10803-007-0482-1

One of the many theories that have been proposed to explain possible causes of autism is the "leaky-gut, opioid-excess" theory. This theory suggests that children with autism have increased permeability of their intestinal track leading to faster absorption of peptides which could disrupt neural development during the early stages of life. To test this theory, the authors measured intestinal permeability in a group of 14 children with autism (diagnosed via DSM-IV criteria by a developmental pediatrician), 7 typically developing siblings of these children, and 8 typically developing additional children. They tested the leaky gut theory in two ways. First they observed the levels of a hormone (GLP-2) in response to feeding, which is believed to control satiation. Low levels of this hormone could lead to, or reflect, dysregulated peptide absorption. Second, intestinal permeability was assessed via a differential sugar-absorption test. They used different types of sugars that have different molecular weights. In a normal intestinal system, sugars with small molecular weight will pass through the walls easily as compared to heavy sugars, leading to high levels of the small sugars in urine. However, in a highly permeable intestinal system, the ratio of these two sugars in urine will change as the sugars with large molecular weights pass through the intestinal barrier at a higher rate. Results: The authors found no differences between any of the 3 groups of children in GLP-2 response to feeding or the ratio of sugars in urine. The authors concluded that in this small sample of children with autism there was no evidence of increased intestinal permeability as hypothesized in the ‘leaky-gut’ hypothesis.

Side note: I always thought "Developmental Pediatrician" was a completely redundant label, and comparable to 'heart cardiologist' or 'eye ophthalmologist'. Although sadly, my experience with some pediatricians does suggest that some really don't know anything about human development.

Autism and Perfect Pitch?

Title: Autism and pitch processing splinter skills: A group and subgroup analysis.
Source:Heaton, P., Williams, K., Cummins, O., Happe, F. (2008). Autism and pitch processing splinter skills: A group and subgroup analysis. Autism, 12(2), 203-219. DOI: 10.1177/1362361307085270

Anecdotal as well as experimental studies have suggested that a sub-group of persons with autism have specific skills that are significantly above what is expected in the general population. Music abilities, and specifically pitch recognition, is one of these abilities. In this study the authors wanted to assess pitch recognition and memory in children (11 to 19 years of age) with Autism with various levels of intellectual abilities (as measured by a non-verbal test, namely: the Raven’s Progressive Matrices) and typically developing children of equal intellectual abilities. The first experiment involved the identification of pitch intervals (major fifths, thirds, etc). However, in order to make this test appropriate for non-musically trained children, the experiment used a computer screen to present a staircase of 8 steps representing the 8 standard tones of a western musical scale (think C, D, E, F, G, A, B, C). The children were trained to recognize each pitch as representing a specific step on the staircase by having a stick figure go up and down the stairs as the pitch changed. After training, an interval was presented (two tones at the same time) pairing the middle C (C4) with another tone. The children were presented with the stick figure anchored on the C step and were asked to move the stick figure to show the other step that represented the second sound in the interval. In the second study, a similar procedure was performed but no anchor was presented, so the children had to remember the pairings of tones to steps, which the authors suggested, was a better measure of traditional “perfect pitch”. The results indicated that as groups, the children with autism did not perform better than typically developing children. However, within the autism group, a subgroup of ‘statistical outliers” was noted. Outliers are data points that are so significantly different than expected based on the performance of the entire group, that statistically they represent anomalies in the data. Often these ‘outliers’ are interpreted as possible errors of measurements, data entry, etc, etc. But this is a great example of when outliers are not errors in the data and actually provide meaningful information. The outliers observed in this study represented a small group of children with autism that scored up to 5 standard deviations above the mean of all groups. None of these children had received music training or were receiving music therapy. More likely, these were children with perfect pitch and the rate of these children in the autism group was disproportional to what is expected in the general population. That is, the data suggest that children with autism are more likely than typically developing children to have significantly above average pitch recognition --- perfect pitch.

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.