AUTISM – CURRENT ISSUES 34
The continuing concern lest a belief that the MMR vaccination is causally linked to autistic spectrum disorder will maintain the drop in uptake of this vaccination (and thus increase the risk of an increased incidence of the diseases in question) led Smeeth et al (2004) further to explore this whole issue via access to the UK General Practice Research Database.
Their study involved a matched case-control study where a comparison was made between individuals born during or after 1973 whose recorded diagnosis of pervasive developmental disorder was noted they were while registered with a general practice between 1987 and 2001, and control individuals matched for age, sex, and location of the general practices. There were 1294 cases in the target group and 4469 cases in the control group.
Of the target group, 1010 cases (78.1%) had MMR vaccination recorded before the diagnosis compared with 3671 cases in the control group before the age at which their matched case was diagnosed.
They were able to conclude that there is no evidence that MMR increased the risk of pervasive developmental disorder …. if anything, the vaccination appeared to be linked with a decreased risk of PDD albeit not of statistical significance.
This lack of association between the vaccination and pervasive developmental disorder was still evident when the study focused upon children with autism rather than any other form of PDD and those vaccinated before their third birthday, and upon the period before there had been any publicity to the hypothesised link between MMR and autism.
While this study might be expected further to limit the continuing concern (and reverse the trend of reduced MMR uptake), the authors commented that there is still an urgent need to identify the actual causal origins of autism.
Meanwhile, and still on the subject of vaccinations and their possible significance in respect of the incidence of developmental disorders, one notes the recent studies which have demonstrated that the use of vaccines containing the preservative thimerasol does not increase the probability of such disorders, but may even be correlated with some improvements in behaviour and cognitive outcomes.
Such evidence is important given that, despite existing findings which have failed to show any support for the thimerasol-disorder link, there may have been maintained a belief among significant numbers of the parent population that there is a danger with, again, some consequent threat to the adequate uptake of vaccinations.
In the first study, Heron et al (2004) followed nearly 13,000 children born during 1991 and 1992 until they were approaching their ninth birthday, with data collected on their exposure to thimerasol-containing diptheria/pertussis/tetanus vaccines given in the early months, and on behavioural, linguistic, motor, and educational performance.
Far from any suggestion that outcomes were worse with increasing exposure to thimerasol, it was found that there were significant inverse associations between exposure and motor development at 6 months and 30 months, between exposure and hyperactivity or conduct problems at 47 months, or exposure and difficulties with sounds or need for speech therapy or other special educational measure at 81 months.
In the second study, Andrews et al (2004) conducted a retrospective cohort study involving more than 107,000 children born between 1988 and 1997.
They, too, noted protective effects from the vaccines containing thimerasol in terms of the reduced risk of general developmental disorders, ADHD, and unspecified developmental delays.
The only condition which seemed to show some increased incidence was the demonstration of tics, but even these were seen as largely transient events.
The joint conclusion referred to the lack of any reason for a change in current immunisation practises.
Recent studies completed by Beaudet et al (2004) confirm that autism does seem to have a significant genetic source, but indicate also that new cases of autism may arise with no apparent genetic predictability.
In other words, the autistic disorder may be a matter of inheritance but may also be “epigenetic” … arising newly in the child rather than inherited. Some predisposing factors may be inherited, while others arise for the first time in the child.
Such a view is in line with existing data from twin studies in that concordance for autism is much higher in monozygotic twins (60% plus) than in dyzygotic twins (around 3%).
Two or more principal genes appear to be implicated, with the gene associated with Angelman Syndrome also thought to play a part in that post-mortem studies of autistic individuals have frequently identified some epigenetic abnormality of DNA at this gene locus. It is further held that environmental factors are likely to interact with endogenous factors leading to newly arising defects.
Within the brains of right-handed individuals without language developmental disorders, it is found that Broca’s area (a region of the frontal lobe associated with language functions) is typically larger in the left hemisphere, with the implication that both language and motor dominance are organised with left-hemisphere dominance in normally-developing individuals.
However, according to the studies using MRI scanning of Harris et al (2004), among language-impaired children with autism or specific language disability, Broca’s area is larger on the right suggesting a divergence of language and motor dominance.
The study involved samples of boys with autism and specific language difficulty, with autism but not language disability, with language disability but not autism, and with no known developmental disabilities.
(A)symmetry of frontal cortex language regions was evaluated via MRI scanning techniques with significant rightward asymmetries in Broca’s area observed in both of the language-impaired groups … a reverse of the typical leftward asymmetry seen in the control sample.
It was also demonstrated that higher verbal IQ scores were associated with the leftward asymmetry.
The authors were not able to determine whether this shift in language region reflects some compensatory process by which to make up for deficits or defects located within the left hemisphere, or whether the split between language and motor dominance somehow underlies the language problems.
However, they did note that these findings suggest that language impairment, which is one of the core elements of autistic dysfunction, is biologically-based and demonstrable in neuro-anatomy and neuro-development.
The current “high-profile” themes of autistic spectrum disorder and the development of thinking skills come together in the work of Beaney and Kershaw (2003) who sought to enhance the thinking skills of children diagnosed with autism and communication difficulties and educated in a mainstream setting. A basic goal was the identification of practical strategies for use by the class-teachers with the autistic children.
Their research began with nine children between the ages of 6 and 11 years, all on a statement and with an ASD diagnosis, and educated in a unit attached to a mainstream primary school. There was an existing pattern of differentiation of the curriculum to compensate for weaknesses in communication and social skills, and of behavioural programme use by which to encourage adaptive behaviours and to decrease unproductive behaviours. A particular focus was upon helping the children to cope in a group setting.
Reference is made to the significance of TEACCH principles by which to ensure that the classroom organisation follows a close routine and structure, with much use made of visual cues and clues, to enable the children to be clear about what is expected of them and to develop increased independence in their day to day working.
Consistency of expectation is further highlighted by the use of distinct areas of the classroom for different activities, plus a visual timetable to provide a constant reminder of what the children should be doing at any given time and what they would be doing next.
Each child has individual work assignments clarifying what they are to do, how much there is, and what to do once the given task has been finished. This arrangement was established to compensate for the observed weaknesses in receptive language … and provided a starting point for autism-specific thinking skill development given the realisation that much of the existing thinking skill approaches depend upon satisfactory use and understanding of oral language.
The authors, however, identified the main thrust in Accelerated Learning (Smith and Call 2001) as associated with building a positive and supportive environment which seemed readily compatible with much of the existing and TEACCH –oriented practice.
Their first step involved observations of the children’s working style and patterns of responses, alongside assessments of strengths and weaknesses. They were assisted by parents, speech therapists, and other support professionals to complete profiles upon the children highlighting performance in different processing styles … auditory, visual, kinaesthetic … and in listening and attention demands, and behavioural and emotional responses.
The eventual components of the thinking skills’ programme included the following :
The authors’ experience and observations have led them to believe that the most significant elements of the programmes and classroom organisation include …..
(One might comment that children with autism provide a very good example of a style of thinking and behaving which [ as Rita Jordan described it ] is not deviant or difficult, but is different. The “autistic triad” of core characteristics, plus specific features such as weak theory of mind or limited central coherence, are enough in themselves to indicate the need to adapt the targets, demands, and presentation of the curriculum.
In other words, if the children with ASD are to be successfully included within a mainstream class for some or most of the time, it is necessary to recognise these differences in language and learning and emotional and behavioural styles, and to adapt the teaching and the environment to them, as opposed to making any assumption that the children can or will adapt to an existing regime appropriate for children with no developmental anomalies.)
* * * * * *
Andrews N. et al ; and Heron J. et al (2004) Mercury-containing vaccines have salutary effects in children. Summary published in Medscape News, with the original material published in Pediatrics 114 577-591
Beaney J. and Kershaw P. 2003 Positive thinking skills. Special ! (Summer 2003)
Beaudet A. et al 2004 Inherited and other factors related to gene expression may underlie autism. American Journal of Medical Genetics (on-line edition : September 2004)
Harris G. et al 2004 MRI reveals changes associated with specific language impairment. Summary published in Medscape News, with the original article published in Annals of Neurology (November) 56 1-11
Smeeth L., Cook C., Fombonne E., Heavey L., Rodrigues L., Smith P., and Hall A. 2004 MMR vaccination and pervasive developmental disorders. Lancet 364 963-969
Smith A. and Call N. 2001 The ALPS Approach. Network Educational Press Ltd
© Mike Connor 2004.
Back to NAS Surrey Branch Welcome Page