Autism Causes and Risks, Latest Findings

Autism causes and risks
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Autism causes and risks are topics of growing concern, especially as the prevalence of this neurodevelopmental disorder has increased dramatically over the past decade. Here are some of the latest findings concerning causes and risk factors for autism.

Pregnancy factor may raise autism risk

The groundwork for development of autism may begin in the womb. Therefore, scientists have explored various pregnancy factors that may raise autism risk.

A new study from England found an association between use of the antiseizure drug sodium valproate during pregnancy and a significant increase in the risk of autism and other neurodevelopment conditions. Specifically, 211 pregnant women with epilepsy took antiseizure medication, and 19 children were diagnosed with a neurodevelopmental disorder by the time they were 6 years old.

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Autism was diagnosed in 12 kids, three had attention deficit/hyperactivity disorder, and four had dyspraxia, which is characterized by lack of coordination. Overall, here were the findings:

  • Neurodevelopmental disorders were more common (7.46%) among women who had epilepsy than among those who did not (1.87%).
  • The increased autism risk was not seen among children born to women with epilepsy who took other antiseizure medications, such as carbamazepine, lamotrigine, or others.
  • After accounting for all factors that could impact the risk of developing autism, the authors concluded that children who were exposed to valproate during pregnancy were six times more likely to have a neurodevelopment disorder.
  • Children exposed to valproate along with other antiseizure drugs were 10 times more likely to develop a neurodevelopmental disorder than those born to women who did not have epilepsy
  • Boys had a threefold greater chance of being diagnosed with a neurodevelopmental disorder than did girls

Other autism causes and risks
Recent research has suggested other autism causes and risks. Here are a few of them women and their doctors should keep in mind:

  • Fever: A study from the University of California Davis reported that women who experienced fever during pregnancy were more than twice as likely to have a child with autism or developmental delays than women who did not have a fever or who took medication to reduce it.
  • Genetics: Scientists have identified a number of genes and genetic mutations that may be involved in causing autism.
  • Older moms: Women who have children after age 35 are at increased risk of giving birth to a child who develops autism
  • Antidepressant use: A Kaiser Permanente Northern California study revealed that use of antidepressants called selective serotonin reuptake inhibitors (SSRIs; e.g., Celexa, Paxil, Prozac, Zoloft) during pregnancy increased the risk of giving birth to children who developed autism. The increased risk was 2.2-fold overall, and 3.8-fold when drug exposure occurred during the first trimester.
  • Close births: A Columbia University study found that autism risk increased when births were close together. For example, among women who became pregnant within one year of giving birth, the risk of having a child with autism was about 7.6 in every 1,000 compared with 2.5 out of every 1,000 when pregnancies were spaced apart three years or longer.
  • Prenatal inflammation: High levels of C-reactive protein (CRP), which is a sign of inflammation in the body, may be a risk factor for autism. The authors of a recent study published in Molecular Psychiatry reported that “The higher the level of CRP in the mother, the greater the risk of autism in the child.”

The rising prevalence of autism is a challenge to parents, healthcare providers, and the individuals who have the condition. Hopefully a better understanding of autism causes and risks will lead to effective ways to prevent and treat this neurodevelopmental disorder.

SOURCE:
Bromley RL et al. The prevalence of neurodevelopmental disorders in children prenatally exposed to antiepileptic drugs. Journal of Neurology Neurosurgery and Psychiatry 2013 Jan 31. DOI:10.1136/jnnp-2012-304270

Image: Morguefile

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