Auckland scientists have discovered how zinc deficiency may have a role in the development of autism, raising the possibility the mineral may in future be considered for treating the disorder.
Studies of children with autism have suggested zinc deficiency may contribute to many cases of autism spectrum disorder, which, including its milder forms, affects around one in every 100 people in New Zealand.
A 2011 study of zinc concentrations in hair from 1967 children with autistic disorders found that nearly 50 per cent of those aged up to 3 years old had zinc deficiency. The rate was around 28 per cent for children aged 4 to 9 and dropped to around 3 per cent for those aged 10 to 15.
People with autism spectrum disorder can have a range of difficulties with language, social behaviour and thinking skills.
University of Auckland scientists, with colleagues in Germany and the United States, have found that cellular changes in the brain caused by gene mutations that occur in autism can be reversed by zinc. Their research is focused on a protein called shank 3, which is associated with neuro-developmental disorders such as autism and schizophrenia.
"My work really is looking at the nuts and bolts of how brain cells communicate," said Associate Professor Johanna Montgomery, of the University of Auckland's Centre for Brain Research and the Department of Physiology.
"There have been a number of genetic changes that have been associated with autism. The ones in shank 3 are the most common.
"What our work shows is that shank 3 can act as a zinc sensor at synapses, between brain cells. What it then does is enhance communication between brain cells.
"What's exciting is that even when brain cells express shank 3 that contains an autism mutation, it is still responsive to zinc. That's great, that the mutation doesn't take away its ability to strengthen and stabilise synapses.
"... We have shown that zinc can increase brain cell communication that was previously weakened by autism-associated changes in shank 3.
"Our work then opens the door to saying, is this a pathway that we can then further follow to look at supplementing zinc [in the diet] and seeing whether this is a way we can improve brain cell communication and as a result improve autism-associated behaviours."
Montgomery said the next step is to investigate the effect of dietary zinc supplements on autistic behaviours.
"Too much zinc can be toxic so it is important to determine the optimum level for preventing and treating autism and also whether zinc is beneficial for all or a subset of genetic changes that occur in autism patients."
The research, which received funding from the Marsden Fund and the Neurological Foundation, is published today in the Journal of Neuroscience.
Montgomery said the study built on the group's earlier work showing that gene changes in autism decrease brain cell communication.
Other researchers have shown in animal models that offspring of mothers on a low-zinc diet are more likely to display autistic-associated behaviours.
Montgomery said, "Our work is showing that even the cells that carry genetic changes associated with autism can respond to zinc."
Autism and zinc
• Half of young infants with autism may be zinc deficient
• Auckland study helps explain zinc's role in the brain
• It found autism-affected cells can still respond to zinc
• Zinc boosts cell communication weakened by autism
• Next step is to test impact of zinc supplements on autism