No Conclusive Proof that Obesity Causes Autism
Friday, 27 April 2012
Letter from Noel Chia Kok Hwee
[Dr Chia is Assistant Professor from the Early Childhood and Special Needs Education Academic Group, NIE]
I refer to the report "Autism may be linked to obesity during pregnancy" (April 10). In recent decades, both obesity and autism have reached epidemic proportions in populations, causing a worldwide alarm.
Today, researchers have made great strides in understanding the phenotype of obesity, with major efforts being directed towards assessing the interactions of genes and environment in the obesity epidemic.
For instance, if one lives in an environment that offers an abundance of calorie-rich food, with few opportunities for physical exercise, there is a higher probability for that person to grow obese.
Family studies have also indicated indirectly that obesity has a genetic component.
However, unlike obesity, no environmental factor per se has yet been identified or established with certainty to account for autism.
Environment can mean everything in the world, from chemicals to diet and lifestyle, which have been identified as the culprits of obesity. Autism studies examining various environmental factors are still inconclusive.
With regards to the genotype of autism and its link to obesity, the genetics of autism is complex. Linkage analysis has been inconclusive.
However, researchers have managed to identify certain variants of a single chemical base along the DNA strand, called single nucleotide polymorphisms of the FTO gene located on chromosome 16p, that appear to correlate with autism and obesity.
The exact location, 16p11.2, has also been associated with developmental disorders and other medical conditions such as Alzheimer's disease.
We need to be cautious about the findings of the study mentioned in the report. Previous similar and provocative studies have attributed children with autism to expecting mothers who smoke tobacco or are of older child-bearing age.
It is important to note that correlation does not equal causation. In scientific research, correlation studies are never used exclusively to claim a cause.
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Source: TODAY, mediacorp