CHAPTER 6: CONCLUSIONS AND RECOMMENDATIONS
2.4 AETIOLOGY OF AUTISM
Put simply, in AD social interaction is mostlymarked by self-isolation or rigid social approaches, and in AS there may be a motivation for approaching others. This, however, may be done in a highly eccentric, one-sided, bombastic, and insensitive manner.
2.3.5 Pervasive Developmental Disorder Not Otherwise Specified (pDD-NOS)
One or more of the following features characterise Pervasive Developmental Disorder Not Otherwise Specified (PDD-NOS): social difficulties or difficulty with two-way social interaction, repetitive stereotyped activities, or a fascination with a specific topic (Wing, 1980; Sicile-Kira, 2003). According to the APA (2000), PDD-NOS includes 'atypical autism' which does not meet the same criteria as any PDD because it begins quite late. According to the diagnostic criteria (Appendix 5), PDD-NOS shows a severe and pervasive impairment in either verbal or non-verbal communication skills,and/or presents stereotyped behaviour,interests,and activities.
Based on the history of autism and current diagnostic criteria, it is encouraging that there has been a burgeoning of knowledge in the field of Pervasive Developmental Disorders (PDD). Itis thus very important to continue investigating the field of PDD for a better understanding of autism,and potential intervention strategies.
parents of children with autism were highly intellectual and mostly not "warm hearted". Further studies did not prove that parents of children with autism were detached from their children. The analyses of the parents' personalities could easily have been biased (Wing, 1971; Furneaux and Roberts, 1977; Woodward and Hogenboom,2000; Dycheset al.,2004).
In the late 1990's the measles, mumps and rubella (MMR) vaccine created a vast domain for investigation, because numerous researchers believed that the MMR vaccine could cause autism. However, frequent studies deny the suggested link between the MMR vaccination and autism (Madsen, Hviid, Vestergaard, Schendel, Wohlfahrt, Thorsen, Olsen and Melbye, 2002). The evidence of a link between the MMR vaccination and autism is weak and based on case-series, cross-sectional and ecologic studies. In a well-conducted study, sthere was no evidence of a sudden increase in the prevalence of autism after the introduction of the MMR vaccine,or of a sudden clustering of cases of autism at any time after immunization (Madsenet al., 2005). No research to date has sufficient statistical significance to establish an association. Nevertheless, The World Health Organisation and other organizations have requested further investigation as it is essential to take maximum care (Madsen et al.,2005).
The following refer to heredity factors as possible causal factors of autism.
2.4.1 Heredity
Hans Asperger and Leo Kanner, in their early studies, noted that both autism and Asperger disorders run in families, sometimes passing directly from father to son, meaning that genes might be central to autism and Asperger Syndrome (Nash, 2002;
Woodward and Hogenboom, 2000;Wikipedia, 2007b). Van Krevelen (1971: 85) also claimed that: "... autistic psychopathy is transmitted genetically via the father".
Scientists today concur that, even if autism does not present in its entirety, families canstill share certain autistic symptoms(Time Magazine,2002).
In the past almost 1 in 20 (5%) siblings of individuals with autism had autism themselves, with a risk of various developmental difficulties (peeters and Gillberg, 1999; APA, 2000), but at present it is estimated at only about 10% (Wallis, 2006).
Consistent research continuously confirms that siblings have a much-increased risk of having autism (Wicks-Nelson and Israel, 1984; APA, 1998; Peeters and Gillberg, 1999). Itis interesting to note that male siblings have lower social competence scores than female siblings (Kaminsky and Dewey, 2002). The latter makes it clear that genes play an influential, although not absolute, role in the development of autism (Dycheset al., 2004).
Studies on twins have confirmed that autism is more frequent in identical twins (homozygous twins) than in non-identical twins (heterozygous twins). If one identical twin has autism, then there is a 60% chance that the other twin will have autism too.
According to Woodward and Hogenboom (2000), the risk of both identical twins having autism varies from 36% - 91%. Today this risk is estimated at 60% - 90%
(Wallis,2006). However,if the other twin does not have autism,then there is a 75%
chance for that twin to exhibit one or more autistic traits (Wicks-Nelson and Israel, 1984; Peeters and Gillberg, 1999; Nash, 2002; Sicile-Kira, 2003; Reichelt, 2005;
Wikipedia,2007b). The above validated the claim for a powerful genetic contribution to the cause of autism. Regions of interest have been found on certain chromosomes, the most important so far on chromosome 7q (Sicile-Kira, 2003): Some researchers have also looked into other possible causal factors for autism.
2.4.2 Biochemical factors
Differences in brain activity have been noted and scientists who study autism agree that some brain circuits are different in a person with ASD. The only key biochemical finding since the 1960s is that the serotonin in a few individuals with ASD and in, some first-degree relativeswho are unaffected,is elevated (Sicile-Kira, 2003;Jordan, 2007c). Anecdotal findings have reported that some children with ASD appear to have biochemical and immunological problems (Sicile-Kira,2003;29).
2.4.3 Other studies in progress
Currently, at the University of California, research is being conducted in the study of hair,blood,urine and tissue samples from family members of individuals with autism, to test for 17 metals, traces of pesticides, opioids and other toxicants (Wallis, 2006).
Some experts believe that the rise in autism is due to diet, vaccines and exposure to pesticides, which affect those with a genetic predisposition to autism (London Daily Mail, 2006). As researchers are still not completely sure what causes autism, it is necessary to continue research into possible causal factors. This is also important to help determine appropriate intervention strategies (c.f. 3.2), which the .educator or other professionals might use within the context of inclusive education,either in a full service school, or a special school suitable for supporting the learner with autism (c.f.
1.2).