The reason for the development of autism has been speculated for decades, but no discovery has quite exactly pinpointed to a singular answer. Often times, the causes are said to be genetic and environmental factors, which generally lacks specificity, to our dismay. However, a new study funded by the National Institute of Environmental Health Sciences (NIEHS) seems to shed some light on how baby teeth might be the first step to finding out the answer.
The new findings indicate that the baby teeth of children who have autism contain more toxic lead (metals) and less of the vital nutrients, namely zinc and manganese in comparison to baby teeth from children without autism. These findings were controlled by studying twins on potential environmental contributors to the disorder, while controlling genetic influences.
As autism is a neurodevelopmental disorder, their study also was longitudinal and focused on development as well. By comparing kids with and without autism, the differences in metal uptake became more apparent, especially during the short time just before and just after birth. The scientists were able to determine this by using lasers in order to map growth rings in the baby teeth generated during various developmental time periods.
“We think autism begins very early, most likely in the womb, and research suggests that our environment can increase a child’s risk. But by the time children are diagnosed at age 3 or 4, it’s hard to go back and know what the moms were exposed to,” said Cindy Lawler, Ph.D., head of the NIEHS Genes, Environment, and Health Branch. “With baby teeth, we can actually do that.”
Confirming their expectations, the study revealed observations of higher levels of lead in children with autism, with the greatest disparity occurring just after birth. Another important observation was that there was significantly lower uptake of the nutrient manganese, before and after birth. Zinc however, was slightly unique on its own– zinc levels were initially low in children with autism, but the levels increased after birth, unlike children without autism. Comparison of the patterns of the lead levels used teeth from 32 pairs of twins and 12 individual twins. Patterns were then compared in the groups consisting of twins where only one has autism, and in twins where either both or neither had autism. As can be inferred, levels in lead varied dramatically between groups of twins where only one has autism in comparison to those who both or neither had autism.
Interestingly enough, the research actually was built on prior research that showed that exposure to toxic metals and lack of vital nutrients had drastic negative effects on the brain’s development.
The study was led by Manish Arora, Ph.D., an environmental scientist and dentist at the Icahn School of Medicine at Mount Sinai in New York, along with support from the NIEHS. Previously, Arora and his colleagues had developed a method using baby teeth and lead exposure levels in children, using lasers to extract layers of dentine for metal analysis. They were able to understand a rough role it played in child development, but until now, they weren’t able to point out that it could be specifically for autism.
Although a major step improvement in autism spectrum disorder research, the research will need to be replicated in order to consider the research more reliably. Despite autism however, this type of analysis regarding levels of nutrients and lead may hold promising results for other developmental research and studies, such those regarding attention deficit hyperactivity disorder (ADHD).