Study links zinc deficiency during pregnancy to autism in babies

Anew study by US and German scientists has suggested that babies that don’t get enough zinc while in the womb may be more likely to develop autism.

The scientists found that zinc shapes the connections or ‘synapses’ between brain cells that form during early development, via a complex molecular machinery encoded by autism risk genes.

They however warn that the research is at its early stage and the findings do not mean pregnant women should start taking zinc supplements to prevent autism.

Till date, scientists don’t have a definitive answer for what causes autism, but most researches show it is down to a combination of ‘environmental factors’ and genetic defects.

The researchers in the study published in the journal Frontiers in Molecular Neuroscience said the study revealed that zinc levels may be one of the defining environmental factors that sow the seeds of the behavioral disorder.

More research is needed to confirm whether there could be a causal link, but the team says they have defined a possible mechanistic link reports Mail Online.

According to the Senior author, Dr Sally Kim of Stanford University School of Medicine, California “Autism is associated with specific variants of genes involved in the formation, maturation and stabilisation of synapses during early development. Our findings link zinc levels in neurons - via interactions with the proteins encoded by these genes - to the development of autism.”

Co-senior author Professor Craig Garner of the German Centre for Neurodegenerative Diseases added: “Currently, there are no controlled studies of autism risk with zinc supplementation in pregnant women or babies, so the jury is still out.

“We really can’t make any conclusions or recommendations for zinc supplementation at this point, but experimental work in autism models also published in this frontiers research topic holds promise.

“Nevertheless, our findings offer a novel mechanism for understanding how zinc deficiency - or disrupted handling of zinc in neurons - might contribute to autism.”

Zinc helps with making new cells and enzymes, processing carbohydrate, fat and protein in food and wound healing.

Foods rich in the mineral include meat, shellfish, dairy foods such as cheese, bread and cereals.

Too much reduces the amount of copper the body can absorb, which can lead to anaemia and weakening of the bones.

The study found that when a signal is transferred via a synapse, zinc enters the target neuron where it can bind two such proteins - Shank2 and Shank3, according to Mail Online.

These proteins in turn cause changes in the composition and function (‘maturation’) of adjacent signal receptors, called ‘AMPARs’, on the neuron’s surface at the synapse.

Lead author researcher, Dr Huong Ha at Stanford explained that “developing rat neurons, we found that Shank 2 and 3 accumulate at synapses in parallel with a switch to mature AMPARs.

“Furthermore, our study shows mechanistically how Shank2 and 3 work in concert with zinc to regulate AMPAR maturation, a key developmental step.”

Co-senior author Professor John Huguenard, also of Stanford added in other words, zinc shapes the properties of developing synapses via Shank proteins.

Prof Huguenard said this suggested that a lack of zinc during early development might contribute to autism through impaired synaptic maturation and neuronal circuit formation.

“Understanding the interaction between zinc and Shank proteins could therefore lead to diagnostic, treatment and prevention strategies for autism,” said Prof Huguenard.