Autism May Result in More Unregulated Synaptic Growth

November 24, 2014

New findings about the brains of people with autism may help lead to a better drug treatment for children diagnosed at a young age. A study recently published in the journal Neuron found that adults and children diagnosed with autism have extra synapses in their brain and have not gone through a synaptic pruning process as extensively as other people.

The study’s researchers, from Columbia University, explained that while most people go through a normal process of synaptic reduction and regulation during childhood, people with autism may not, which leads to a significant change in the brain’s function. Researchers reminded that although synaptic growth is commonly associated with learning, removing bad synapses can also be powerful for improving brain function. These findings are significant because the issue may be able to be addressed with drugs that inhibit mTOR, which allows for brain to destroy its own cells.

Finding a potential treatment for autism

The neuroscientists gave mice with autism rapamycin, a drug that was designed to address the pruning problem by inhibiting mTOR. The results of the experiment were positive. Scientists observed improvement in autistic behavior among the mice even after they had already exhibited symptoms of autism. This drug cannot be given to humans with autism, but the results are promising for finding another drug that has similar results, the researchers explained.

“What’s remarkable about the findings is that hundreds of genes have been linked to autism, but almost all of our human subjects had overactive mTOR and decreased autophagy, and all appear to have a lack of normal synaptic pruning … Overactive mTOR and reduced autophagy, by blocking normal synaptic pruning that may underlie learning appropriate behavior, may be a unifying feature of autism,” said David Sulzer, study investigator and professor of neurobiology at Columbia University Medical School.

One reason that mTOR is an important part of autism research is that there are hundreds of genes suspected of driving the condition. The genes cluster into a smaller number of pathways, which the researchers say include mTOR. This study may not have come out with an effective treatment option for humans, but it may have laid the groundwork for future drugs or treatments.

According to the U.S. Centers for Disease Control and Prevention’s Autism and Developmental Disabilities Monitoring Network, the rate of children with an autism spectrum disorder has increased from 1 in 150 in 2000 and 2002 to 1 in 68 in 2010. Children of parents who are older or who have autism are more likely to have an autism spectrum disorder.