What are the Causes of Autism?
Do we really know when its diagnosis is based on behaviours?
NB. I am still adding content to this page...It will include my personal hypotheses.
There is no one known cause for autism. It is still a disorder being researched within many disciplines in many countries.
Some suggested and known contributory factors for the cause of autism:
.... Leo Kanner and Leon Eisenberg started the concept that emotionally frigid parents were partially to blame for their child’s autism. Leo Kanner later created the expression ‘refridgerator mothers’ after observing some mothers appeared socially and emotionally detached from their children (Kanner and Eisenberg, 1956 cited in Feinstein, 2010; Roth, 2010). Bruno Bettleheim reinforced this blame in his book ‘The Empty Fortress: Infantile autism and the birth of self.’
Surprisingly, some European countries still believe that mothers are to blame for their child’s autism (Feinstein, 2010). The impact of this accusation caused immense stress to parents and many mothers became emotionally scarred due to it. However, some parents challenged this view and set up the National Autistic Society (NAS) in the UK and the Autism Society of America (ASA).
One father, Bernard Rimland, founder of the ASA, became one of the most influential persons in research for the aetiology and intervention of autism. Biological and environmental causation for autism began to be investigated besides other psychological perspectives (Roth, 2010; Feinstein, 2010; Autism Research Institute (ARI), 2000; ASA, 2010).
Genetics: Genetic research has increased immensely in the first decade of the 21st century and studies conducted on identical twins have confirmed the genetic influence in the cause of autism (Feinstein, 2010; Baron-Cohen, 2008; NAS, 2010). Many individuals with autism often have members in their family or extended family who present some behaviour on the spectrum or have a condition, either diagnosis or undiagnosed, associated with it.
In a review of the research, Freitag concluded a heritability percentage of more than 90 percent for the narrow autism phenotype (NAP) (a person with many autistic traits), a common genetic liability for social communication and interaction for ASD and the Broader Autism Phenotype (BAP) (a person with less autistic traits); and a separate genetic cause for individuals with restricted and repetitive behaviours.
Although, there appears a bias towards males having ASD, findings for an abnormality on the X chromosome are scarce (men have one and women have two x chromosomes) (Muhle et al., 2004; Freitag, 2007; Abrahams and Geschwind, 2008).
In March 2010, at Lorna Wing's conference, it was suggested there are many undiagnosed females with ASD, possibly due to them displaying the autistic behaviours in a different way to males. Anorexia Nervosa was also implicated as being a condition on the autistic spectrum with respect to it causing similar cognitive, perceptual and repetitive restricted behaviours (Wing et al, 2010 Hughes, 2008).
Other undiagnosed conditions, which an individual diagnosed with ASD may have, can confuse an already complex, diagnostic process for ASD (Gillberg, 1992). Mental Retardation (MR) is also diagnosed on behavioural criteria. Other conditions which present autistic behaviours but can be genetically identified are:
Fragile X syndrome (FRAXA),
Prader Willi (PWS),
Potocki-Lupski (PLS) syndromes
Tuberous Sclerosis (TSC).
As it is not routine to take blood tests when assessing for ASD, these conditions may remain undiagnosed (WHO, 1992; APA, 2000; Freitag, 2007; Hughes, 2008; Abrahams and Geschwind, 2008).
Freitag recommends that all cases of ASD where mental retardation is also present, should be assessed for FRAXA and that TSC, even with no seizures present, should be assessed with a special tool called a 'Wood’s light,' because genetic counselling is relevant for both disorders. He also recommends assessment for SLO because this condition can be treated with dietary cholesterol supplementation.
The impact genetic research has had on our understanding of the cause of autism is that it is now recognised, in many worldwide countries, but as previously mentioned not all, that some children are born with a genetic susceptibility to environmental triggers; which may or may not cause them to develop autistic behaviours, in varying degrees of severity, in all or some of the autism triad of impairments (Feinstein, 2010; Freitag, 2007; NAS, 2010; GHR, 2010; Ronald et al., 2005).
Environmental factors: recent research has found that environmental factors play a larger contribution than previously thought in the cause of autism but the most controversial environmental factor concerning many parents is that of vaccination, especially the MMR which you can read about by clicking on the link below...
...MMR vaccine : Epidemiological research has been used to refute this link as a cause for autism but even the Medical Research Council state this can not be used to categorically disprove a link.
Mercury Poisoning via vaccines: the preservative Thimerosal/Thiomersal: The symptoms and behaviours for mercury poisoning mirror the ones for ASD but this is still controversial and needs more scientific research 'evidence' for some professionals to consider this may be a possible cause, contributary one for autism or a separate condition.
It is worth noting that since 2002 all UK and USA childhood vaccines have been Thiomersal (Thimerosal) free (AAP,1999;DOH,2003).
WARNING: My work has been through an electronic plagiarism service so if you wish to use it, PLEASE remember to reference it!
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AUTISM RESEARCH INSTITUTE (ARI). 2010. Triggers of autism.[WWW]. http://www.autism.com/faq_triggers_of_autism.asp (6 December 2010).
AUTISM SOCIETY OF AMERICA (ASA).2010. Autism and vaccines.[WWW].http://www.autism-society.org/site/PageServer?pagename=research_envirohealth_vaccines (6 December 2010).
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MEDICAL RESEARCH COUNCIL (MRC). 2001. [WWW]. MRC Review of Autism Research: Epidemiology and Causes. http://www.mrc.ac.uk/Utilities/Documentrecord/index.htm?d=MRC002394 (27 December 2010)
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