Autism Awareness Campaign - Causes of Autism

Today’s poster in Autism Awareness series touches up on causes of Autism.

Never there was any agreement between experts on Causes of Autism, and exact cause of Autism is not known. There was a report in 1998, that proposed a link between autism and MMR (measles, mumps and rubella) vaccine.  This study has been debunked by other research and was eventually retracted in 2010.

Experts believe that there are certain factors that may increase risk.

Genetic factors:  It is believed that if you have a brother, sister, twin or parent with ASD (Autism Spectrum Disorder), you are likely to develop it as well.  After getting to know many families with an autism child, I have hardly seen such a situation.  Unfortunately this stigma still stays, and I know quite a few families finding it difficult to get marriage alliance for siblings of Autistic persons. 

ASD rates seems to be much higher among children with fragile X syndrome and tuberous sclerosis.

Environmental factors: Some experts suspect that exposure to heavy metals (especially Mercury) and other toxins in the environment raises risk of ASD.  If mother takes drugs with heavy metals / toxins while she is pregnant, that raise the risk.

Some expert say, low birth weight is a risk factor.  It was true with Pratibha’s case.  Her birth weight was low.  I’m not sure, what led to low birth weight.  Couple of doctors told us that not getting sufficient oxygen at the time of birth could lead to injuries in brain, resulting in higher risk.  I suspect, this could be reason in Pratibha’s case.   A PET scan of brain much later confirmed that there are quite a few inactive areas in the brain. 

Now the question of “What is the reason for high rate of increase for prevalence of autism”? 

Most common issue cited for increase in ASD prevalence are frequently changing diagnostic criteria for the ASD and even the definition of subcategories of autism and autism related disorders.  

Survival rates of premature infants increased over a period of time.  The premature / low birth weight babies are likely to be affected by neuro-developmental disorders including autism. This adds to increased rate of prevalence.

Research methodologies followed for estimating prevalence of ASD varies.  Even this adds to inaccuracy in numbers.

Higher rate of increase is observed in last couple of decades in developed countries, possibly because of factors related to lifestyle. 

Still the causes and reasons for increase of Autism prevalence seems to be very subjective. Lots of unknowns.. We are wading through an unknown territory..