Several studies published in the last week have implicated various prenatal factors that may lead to the development of autism spectrum disorder (ASD).
One study, published Thursday in the Journal of Neurology, Neurosurgery and Psychiatry, contends that prenatal exposure to an antiepileptic drug called valproate, which has been previously linked to congenital defects, has now been linked to an increased risk for the development of ASD.
In this large longitudinal study, 415 children were studied, with 214 control participants and 201 children born to mothers with epilepsy, with developmental assessments conducted at 12 months, 3 years and 6 years of age. Of the 528 women included in the study, 243 had epilepsy, 209 of whom were on antiepileptic drugs.
The researchers found that a child was six times more likely to develop a developmental disorder if the mother was on one antiepileptic drug, and 10 times more likely if the mother was on multiple drugs. The most common developmental disorder was ASD.
It's important to note that the majority of prescriptions for antiepileptic drugs are for psychiatric deficits and pain, with less than half of the prescriptions in the United States being for the treatment of seizures or epilepsy.
Another study also published Thursday details a hypothetical study which would look at a particular biomarker, in this case a growth protein called insulin-like growth factor (IGF), as a predictor for the development of ASD. Based on prior research, the scientists propose that decreased levels of IGF in the blood of newborns could serve as this biomarker.
IGF serves to produce myelin, which insulates brain cells in order to effectively transmit neural signals. In the developing fetal and infant brain, myelin is vital for the formation of neural pathways between different regions of the brain. Depressed IGF levels leads to insufficient insulation and thus insufficient neural signals and communication, which has previously been observed in brain biopsies of people with ASD.
The proposed study would look at a sample of umbilical cord blood after birth to measure IGF levels, and compared to the baby's neurological evaluation at 18 and 36 months. Following this, the next phase would look at IGF levels in amniotic fluid during pregnancy. IGF levels can be supplemented prenatally or through pharmaceuticals postnatally.
Finally, a study released last week in the journal Molecular Psychiatry finds that maternal inflammation during pregnancy may be related to an increased risk of ASD. Researchers measured inflammation through levels of C-reactive protein (CRP), a marker of systemic inflammation.
The study utilized a national birth cohort called the Finnish Maternity Cohort which contains an archive of 1.6 million specimens from about 810,000 pregnant women, using biomarker data to look back to a critical time during development in early pregnancy. After compiling this data, the researchers found that the risk for ASD was increased by 43 percent among mothers with CRP levels in the top 20th percentile, and by 80 percent for maternal CRP in the top 10th percentile.
Each of these three studies looked at prenatal factors for the development of autism spectrum disorders, implying that numerous factors may play a role well before birth.
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