A deficiency in vitamin D on the mother’s side could explain why autism is three times more common in boys, say researchers from The University of Queensland.
In their latest study, Professor Darryl Eyles and Dr Asad Ali from UQ’s Queensland Brain Institute found vitamin D deficiency during pregnancy caused an increase in testosterone in the developing brain of male rats.
“The biological cause of autism is unknown but we have shown that one of the many risk factors—low vitamin D in mothers—causes an increase in testosterone in the brain of the male foetuses, as well as the maternal blood and amniotic fluid,” Professor Eyles said.
“In addition to its role in calcium absorption, vitamin D is crucial to many developmental processes.
“Our research also showed that in vitamin D-deficient male foetuses, an enzyme which breaks down testosterone was silenced and could be contributing to the presence of high testosterone levels.”
Professor Eyles’ previous research has shown that vitamin D plays a critical role in brain development and that giving vitamin D supplements to mice during pregnancy completely prevented autism like traits in their offspring.
Co-author Dr Ali said that excessive exposure of the developing brain to sex hormones like testosterone was thought to be an underlying cause of autism, but the reasons remained unclear.
“Vitamin D is involved in pathways controlling many sex hormones,” Dr Ali said.
“When the rat mothers were fed a low vitamin D diet, it caused male foetal brains to have high levels of exposure to testosterone.”
Professor Eyles said the study was the first to show that a known risk factor for autism alters testosterone in both the foetal brain and the mother’s blood — one possible contributor to why autism is more prevalent in males.
This research is published in Molecular Autism.
