Scientists say people with autism might have too many brain connections, causing communication problems in their nervous systems.
At the root of the issue is a malfunctioning gene within the brain cells called neurons. The RNF8 gene helps to regulate the connections, known as synapses, between these neurons that allow communications to travel between them. When that gene is not working properly, too many synapses form and overload the system — they confuse the brain. Scientists say this could be one of the key causes of symptoms in autism, the developmental disorder characterized by social difficulties.
“You might think that having more synapses would make the brain work better, but that doesn’t seem to be the case,” senior author Dr. Azad Bonni said in a statement from the Washington University School of Medicine. “An increased number of synapses creates miscommunication among neurons in the developing brain that correlates with impairments in learning, although we don’t know how.”
The researchers saw this in action when they removed the RNF8 gene from rodents’ cerebellums, one of the regions of the brain that is affected by autism and a control center for a person’s motor skills and cognitive functions like language. The neurons in those rodents created about 50 percent more working connections to other cells. According to the university, the scientists were able to measure the higher intensity electrical signal heading into cells when these connections were increased.
Although the rodents with the missing RNF8 gene did not experience motor issues, they had trouble learning new ones.
“It’s possible that excessive connections between neurons contribute to autism,” Bonni said. “More work needs to be done to verify this hypothesis in people, but if that turns out to be true, then you can start looking at ways of controlling the number of synapses.”
Scientists have previously identified a possible link between autism and a mutation in the RNF8 gene, although it has been unclear how the gene mutation affects the brain and what that has to do with autism.
The gene is part of a group called ubiquitin ligases that are responsible for telling cells what to do with certain proteins they encounter.
The new study, published in the journal Nature Communications, asks what the biological significance would be of stopping synapses from forming between neurons, and suggests that it could serve to prevent the synapses from connecting brain cells without a purpose — in the absence of learning a new skill. It could also “provide the means to fine-tune neuronal connectivity once synapses are formed.”
This isn’t the first time scientists have suggested a gene that could seemingly enhance brain power is related to autism. Earlier this year, a separate team wrote a paper explaining that the genetic mutations associated with the disorder may have been passed on through the generations — surviving an evolutionary process that is supposed to root out negative genes — because the same ones that cause autism also improved our cognitive abilities. Those researchers had seen an association between people carrying autism genes and bigger brains, enhanced sensory capabilities and better decision-making skills.