Autism Regression: A prevalence study

A review of: Baird, G., Charman, T., Pickles, A., Chandler, S., Loucas, T., Meldrum, D., Carcani-Rathwell, I., Serkana, D., Simonoff, E. (2008). Regression, Developmental Trajectory and Associated Problems in Disorders in the Autism Spectrum: The SNAP Study. Journal of Autism and Developmental Disorders DOI: 10.1007/s10803-008-0571-9

Although most children with autism present very early signs and symptoms and a linear developmental trajectory, a small subset of children present a trajectory characterized by normal development followed by a loss of acquired skills or a failure to use the acquired skills. This pattern has been termed autistic regression. Possible explainations for this phenomenom have varied from a genetic effect on brain restructuring and pruning during the early stages of life, to enterocolitis due to vaccinations, to epilepsy. In this study, the authors explored differences in developmental outcomes for children with and without regressive autism, and the association between regression and enterocolitis and epilepsy. This study examined a population cohort born in the UK in 1990 and 1991. Out of 56,946 children in this cohort, 218 had and ASD diagnosis by age 10. A subset of these children were evaluated via ADOS and ADI and divided into a broad autism (N=105), narrow autism (N=53), and no autism (N=97). The narrow autism group met full criteria for autism based on ICD-10. The broad autism group met clinical consensus for autism but not full ICD-10 criteria. These children were then evaluated for history of epilepsy, gastroinstestinal problems, and developmental regression. 39% of children with narrow autism had a history of regression during development. This compared to 11% of children with broad autism, and 3% of children with no autism. On average this regression occurred around the 25 month of age. There were no differences in IQ or adaptive functioning between those with or without regression. However, those with regression classified in the broad autism group had significantly more symptoms than those without regression also classified in the broad autism group. Regression was not associated with gastroinstestinal symptoms or with epilepsy.

Autism and Parental Psychiatric Disorders

A brief review of: Daniels, J.L., Forssen, U., Hultman, C.M., Cnattingius, S., Savitz, D.A., Feychting, M., Sparen, P. (2008). Parental Psychiatric Disorders Associated With Autism Spectrum Disorders in the Offspring. PEDIATRICS, 121(5), e1357-e1362. DOI: 10.1542/peds.2007-2296

The journal of Pediatrics just published a population study based on the national Swedish registry, which examined the association between parental psychiatric history and autism. The authors compared the parental psychiatric history of 1,227 of children with autism spectrum disorder and 30,925 typically developing children. Children were identified as having autism spectrum disorder if they were born between 1977 and 2003 and had a diagnosis of ASD recorded in the registry between 1987 and 2003.

Parents of children with autism were 70% more likely than parents of typically developing kids to have a psychiatric diagnosis. When both parents had a psychiatric disorder, the children were 100% more likely to have a diagnosis of autism. Schizophrenia was more common in both parents among children with autism as compared to parents of typically developing kids (90% more likely for mothers and 110% more likely for fathers). In addition, mothers of children with autism were more likely than mothers of typically developing kids to have depression (70%), and personality disorders (70%).

In summary, the study suggests that in Sweden, during the last 30 years, children with a diagnosis of autism were more likely to have parents with psychiatric diagnoses than typically developing children. This could reflect a non-specific, possibly genetic, predisposition in affected families for psychiatric conditions, including autism. It could also reflect that having a child with autism increases stress in the parents possibly leading to psychiatric diagnoses. However, the association noted by the authors was even stronger if the parental diagnosis was provided before the child’s diagnosis. One important consideration, these results were based only on kids who had a history of inpatient treatment. Those with a history of only outpatient treatment were not included. It is possible that the observed link between parental psychiatric history and autism applies only, or mostly, to the most severe cases of autism requiring hospitalization.

One last comment: It's important to note that the rate of psychiatric conditions among even children with autism were very low. For example, schizophrenia was observed among 0.6% of the mothers of children with autism (compared to 0.2% of the typically developing mothers). 99.4% of the children with autism did not have mothers with schizophrenia. Therefore, the data only suggest that there may be a familial/genetic predisposition that is related to autism among very small subset of children with autism.

Autism and Inhibition of Return - A note about sample size

A review of: Rinehart, N.J., Bradshaw, J.L., Moss, S.A., Brereton, A.V., Tonge, B.J. (2008). Brief report: Inhibition of return in young people with autism and Asperger's disorder. Autism, 12(3), 249-260. DOI: 10.1177/1362361307088754

The authors designed an interesting experiment based on Minshew’s Complex Information Processing theory of autism, which seeks to understand the neuropsychological patterns of strengths and weaknesses in Autism as the foundations for the specific deficits in social cognition observed in Autism.

Side Note: Please note that the ‘Neuropsychological’ is usually misinterpreted, even by trained researchers and clinicians, as referring to physiological, as in ‘biological psychology’. Instead, neuropsychological refers in general to neurocognitive functioning – that is, cognitive and motor domains linked to brain processes. Thus, a test of neuropsychological functioning would include assessment of memory, attention, motor control, visual perception, auditory skills, general intelligence, language, etc.

Neuropsychological researchers have noted intact or superior abilities to detect unique patterns or items in visual search tasks in children with autism. This is inconsistent with the finding that these children also show difficulty with visual orientation and attentional set-shift (controlling the shifting of attention when needed from one set of items/tasks to others). Thus, how could children with autism have excellent item detection skills in light of their difficulty with attention and visual orientation? One possible explanation explored by the authors is that children with autism have a pronounced Inhibition of Return (IOR). IOR is a cognitive process that facilitates visual search by inhibiting searching on areas that have already been searched. For example, when looking for a letter ‘p’ on a poster full of letters ‘b’ and ‘d’, IOR allows you to search more effectively and those with a more pronounce IOR would be faster.

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In this study the authors compared 12 kids with high functioning autism, 12 kids with Asperger’s, and 12 typically developing kids, all matched for age (mean 10), sex, and IQ. Diagnoses were confirmed via ADI. The participants completed a series of tasks to measure IOR. The authors found no significant differences in IOR between those with ASD and typically developing kids. However, there was a trend at the (p = .052) level suggesting a more pronounced IOR among children with Asperger’s than the other two groups. This is worth noting because the authors ability to find statistically significant results is directly affected by the number of participants in each group. Thus, if these same results had been obtained with more participants, it is very likely that the difference observed would be statistically significant. This sample size related effect is more of a concern when the N of participants is very small. Thus, I will be more likely to ‘trust’ non-significant findings from a study using 1,000 participants than those from a study using only 20. One rule of thumb you can use when examining studies with small sample size (number of participants) is that statistically significant results are more "informative" than results not showing statistical significance. Why? Because the small sample size makes it more difficult to find statistically significant differences, so they require greater differences between the groups you are comparing. Thus, when you see a study using a small sample size that found a statistically significant difference, you can assume that the difference between the groups is there (assuming no other methodological problems). However, when the results show no statistical difference, this could mean that the difference between the groups does not exist, or that they needed a larger sample size.