Since the 1990s there has been a worldwide explosion in cases of autism. Once a rare neurological disorder that affected only one in 10,000 children, and often from birth, it is now affecting as many as one in 66. Many cases are regressive, where the child is born normally and develops appropriately for his age, then loses previously acquired skills including his language.
Boys are three times more likely to get autism compared with girls. A Cambridge University study in the UK found that one in 40 British boys is autistic or has some form of ASD.
But what causes autism? That has been a question that has been asked since 1943 and scientists aren’t completely sure. In truth, autism is probably caused by a combination of factors.
Helen V. Ratajczak, researcher in the Journal of Immunotoxicology, wrote:
"Documented causes of autism include genetic mutations and/or deletions, viral infections, and encephalitis following vaccination. Therefore, autism is the result of genetic defects and/or inflammation of the brain." (1)
Theoretical causes of autism that researchers have studied so far, include:
Some cases of autism are believed to be genetic in origin. Studies of identical twins have shown that if one twin is autistic, the other twin is 90 percent likely to have autism too. Relatives of autistic individuals may have one or more symptoms associated with autism but not enough to be diagnosed with the condition. (1)
Identical twins have the same DNA, though, so they may be susceptible to the same environmental factors and this could account for the high rate of sibling autism.
Other theory is that alterations in gene expression or mutations in genes could be responsible for autism, although no gene has been found to be responsible for autism and some researchers think that genetics do not account for autism because there has been an epidemic increase in cases throughout the world and there is no such thing as a genetic epidemic. (1)
The CDC admitted that genetics cannot account for the increase in cases and many studies of the issue have strengthened this position.