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14. Are there risk factors for autism?

 Many studies have sought to identify risk factors for autism with the hope that finding the risk factor could lead to finding a cause of autism, measures to prevent autism, or at least help to identify autistic children earlier than now is possible.

While studies have found some associations, none has been identified as “causative.” Researchers in one study examined the medical records of nearly 700 autistic children and their parents. This data came from Denmark’s national health care system, which has records on virtually all Danish children diagnosed with autism. The study evaluated every child diagnosed with autism between 1968 and 2000. Each of the nearly 700 autistic children was compared with 25 kids without autism.

The researchers looked for issues such as medical problems the mothers may have had during pregnancy, difficulties during the birth of the child, history of mental disorders among the parents, and any illnesses the child had between birth and the diagnosis of autism.

Researchers found that parental psychiatric histories prior to the child’s diagnosis of autism had the highest association with autism. When considering all the risks, parental psychiatric history increases the risk of an autism diagnosis by three-to fourfold.

Another group of researchers noted that head size at birth among the autistic children was smaller, on average, than the children who did not develop autism.

However, during the first year of life, these children experienced sudden and excessive brain growth such that their brains were larger than all but 15 percent of all measured children. This excessive growth in head size occurred well before the onset of behavioral symptoms.

These researchers went on to report that the “degree, rate, and/or duration” of the excessive brain growth may be predictive of the severity of later symptoms of autism.

The following is a list of conditions that occur more commonly in autistic children than in typical children:

  • Delivery-associated risk factors:
  • Breech presentation of the baby
  • Low Apgar score, an index used to evaluate the
  • Condition of a newborn 5 minutes after birth
  • Premature birth: (a birth before 35 weeks of pregnancy)

Parental history of mental illness:

  • Schizophrenia-like psychosis
  • Affective disorder, which includes some psychoses, depression, and bipolar disorder

Childhood developmental history:

  • Rapid and excessive growth in head size during the first year of life

No associations have been found between autism and:

  • Infant weight
  • Number of previous babies born to the mother
  • Number of doctor visits before pregnancy
  • Parental age at time of birth of child
  • Socioeconomic status

 Note:

 Another group  of researchers noted that head size at birth among the autistic children was smaller, on average, than the children who did not develop autism.

 Terms:

 Psychosis - A mental and behavioral disorder causing gross distortion or disorganization of a person’s mental capacity, affective response, and capacity to recognize reality.

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