health

The causes of autism are not well understood. In the 1950s many psychiatrists
thought that autism was caused by cold or distant parenting—
“refrigerator mothers” was a common term—and blamed parents for the
disorder. This theory has been disproved by careful studies of families with
autistic children. In the 1990s some people theorized that autism is caused
by childhood immunizations, particularly the measles-mumps-rubella or
MMR vaccine. In 2007, however, a report published in the New England
Journal of Medicine showed that vaccines do not cause autism; it is simply
that the early symptoms of autism often appear at the age when children are
given the MMR vaccine.
Other possible causes of autism that are still being investigated
include:

• Genetic factors. It is known that parents of an autistic child have
  an increased risk (one chance in twenty) of having a second child
  with the disorder. No specific gene or genes associated with autism
  has been identified, however.
• Viruses or other disease agents. Women who have rubella during
  pregnancy have an increased risk of having an autistic child.
• Father’s age. One study showed that fathers over forty when their
  child was born are six times as likely to have an autistic child as
  fathers who were thirty or younger. The mother’s age doesn’t seem
  to make a difference.
• Difficult pregnancy or childbirth. Some doctors think that
  damage to a baby’s brain before or during birth may play a role
  in autism.
• Exposure to pesticides and other toxic chemicals. There is some
  evidence from two studies done in California in 2007 that women
  exposed to certain pesticides during the first three months of pregnancy
  have an increased risk of having autistic children.

Common symptoms of autism have already been described; others
are listed in the sidebar. Conditions that are often found in children with
autism include:

• Mental retardation. About 75 percent of children with autism are
  mentally retarded, which complicates diagnosis of the disorder.
• Seizures.
• Self-injury or aggressive behaviors toward others.
• A loss of previously attained language or social skills. The child
  appears to develop normally until about fourteen months of age
  and then starts losing his or her ability to talk and interact with
  others.