Many theories have been put forth regarding the causes of autism, ranging from the genetic to the environmental. In spite of the many advancements in the field of autistic spectrum disorder research however, there are still very little conclusive facts about what exactly causes this condition.

Because autism has been observed to run in some families, the theory that autism is caused by genetic factors has been given some consideration. It is well known in the medical community that the condition manifests itself in many different ways in different people. Because of this, scientists now suspect that there may in fact be a number of different genes that are responsible for the occurrence of autism.

Today, research efforts in this area are focused on determining which particular genes are responsible for passing on the condition from one generation to the next.

One of the more controversial theories regarding the possible causes of autism is that it is somehow related to the use of vaccines. Two areas have come into concern in particular: the use of Thimerosal and the administering of the MMR or mumps­-measles-rubella vaccine.

Thimerosal is a mercury-based preservative that was widely used in many vaccines during the late 80s all the way up to 2003. While the mercury in Thimerosal is supposedly flushed out naturally from the body after six weeks, many people who blame vaccines for causing autism feel that children of that age are incapable of clearing out the ingredient from their bodies.

Furthermore, it is thought that these vaccines contained mercury in amounts that is far above the FDA-approved safe level.

As for MMR, this vaccine is typically given to children at an age when the symptoms of autism normally become apparent. This, along with the fact that the vaccine is comprised of three different and powerful viruses has given rise to concerns that it somehow affects a child's immune system adversely, causing them to become weaker. Consequently, a series of autoimmune reactions start, which ultimately results in autism.

In any case, the jury is still out on what the exact causes of autism are and research is ongoing to this day.

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