Causes Of Autism

[George Giles]

Causes of autism are largely unknown. However, there are a number of
theories surrounding the cases of autism that we see. There are also
some conflicting opinions focusing on whether or not there has been a
sharp rise in the cases of autism in the past 10 years.
If you have an autistic child, it is important to know that autism is
not a psychological disorder. Researchers have long dispelled the myth
that autism is caused by the lack of a nurturing mother. Hence, if
your child has been diagnosed with an autism disorder, know that it is
not caused because you were a bad parent.
Genetic Causes Of Autism Many studies strongly suggest that autism
cases are caused by inherited genes. It has been found that the
incidence of autism in the general population is approximately 1.5 in
1000 people, but parents with an autistic child have a 1 in 20 chance
of having another autistic child.
Many neurobiologists also say that autism is the most heritable of all
the neurobiological conditions. The most persuasive evidence is the
research done in twins. Twin studies can help establish a genetic link
for a condition by noting the difference in prevalence of the
condition in identical (monozygotic) and fraternal (dizygotic) twins.
If a condition is genetic in origin, the prevalence will be markedly
higher in monozygotic twins, since they share the exact same
chromosomes. In most twin studies conducted for autism, the prevalence
of autism is as much as 90% higher in monozygotic twins than in
dizygotic twins.
The studies themselves are subject to controversy, however. The fact
that not one of the studies showed 100% concordance in monozygotic
twins suggests that there could be other factors at play in the cause
of autism. Other familial studies have noted common characteristics -
for instance, that autism is more common in families of physicists and
engineers. This observation gave rise to the term 'the geek syndrome'
to identify autism.
Environmental Causes Of Autism There are also many researchers who
believe that environment factors can be causes of autism. Dr. Bernard
Rimland proposed in 1967 that autism is caused by mercury and heavy
metal toxicity to which some children have a genetic sensitivity. His
treatment of autistic children with a gluten-free, casein-free diet
and mercury chelation therapy (removal of mercury from the system) has
shown great success with some children.
Other environmental factors that can possibly play a part in causing
autism include viral or bacterial infections, vaccines and
thalidomide.
The Supermale Brain Theory One particularly interesting recent theory
is that autism is caused by high levels of testosterone during
development. A study in England measured the testosterone level of the
amniotic fluid in mothers, then followed up with testing of children
after birth and at four years. They found that the babies with the
highest levels of testosterone pre-birth had a smaller vocabulary and
made eye contact less often at a year old, and were less socially
developed at age four.
The theory concludes that high testosterone levels in the brain
support the development of 'male skills' like analysis of systems and
seeing patterns, but repress the development of 'female skills' like
communication and empathy. Autistic children tend to be lacking in the
'female skills'.