In a significant finding, researchers have revealed that alcohol consumption during pregnancy interferes with the genetic processes that control thyroid hormone levels in the fetal brain, thus leading to neurodevelopmental disorders.
Fetal alcohol exposure-even from moderate drinking during pregnancy-can cause emotional behavioural disorders and deficits in learning, memory and speech.
Previous studies have shown that some of these lasting cognitive impairments occur because alcohol consumption during pregnancy decreases the level of maternal thyroid hormones and, therefore, fetal thyroid hormones.
"Specific concentrations of thyroid hormones must be available in the fetal brain to support normal neurological development," said study author Laura Sittig, a student at Northwestern University Feinberg School of Medicine.
She said one of the enzymes that control thyroid hormone levels in the fetal brain is the iodothyronine deiodinase type III, or Dio3.
The study showed that fetal alcohol exposure disrupts the epigenetic "imprinting" of Dio3.
In this process, Dio3 normally originates from the father's gene, while the maternal gene is silenced by epigenetic control. But alcohol exposure changes the paternal-maternal dosage of Dio3, which increases the amount of the enzyme present in specific brain regions of the fetus, the authors found.
This increase reduces the availability of vital thyroid hormones in the parts of the brain that control learning, memory and emotional behaviours.
"In light of our current finding, we can begin testing specific dietary supplements that could reverse the epigenetic alterations that disrupt the regulation of Dio3," Sittig said.
"When given to the mother or newborn, this might correct the imprinting deficits induced by alcohol.
"This is a promising avenue to improve the prognosis of alcohol-related neurodevelopmental disorders, for which we currently have no intervention strategy," she added.