Young people who suffer from autism spectrum disorder have excess brain synapses that have not been “pruned” enough during their development, which may lead to the development of the condition.
Synapses, the points where neurons connect with each other, are known to be impacted by genes related to autism, and some scientists believe people with autism have extra synapses.
Guomei Tang, PhD, a research scientist at Columbia University Medical Center (CUMC), New York, and colleagues examined brains from children, both with and without autism, who had died from other causes.
The density of spines that branch out from neurons and connect via synapses had declined by about 50% in healthy children by late childhood, compared to only 16% in the brains of adolescents with autism, the researchers reported in Neuron.
They also found that the drug sirolimus (Rapamune), which is used to prevent organ transplant rejection, restored synaptic pruning and improve autistic-like behavior in mice. However, the drug’s side effect profile may limit its potential use for autism.
“The fact that we can see changes in behavior suggests that autism may still be treatable after a child is diagnosed, if we can find a better drug,” study senior investigator, David Sulzer, PhD, a neurobiology professor at CUMC, said in a prepared statement.
Children and teens with autism have a sluggish brain “pruning” process during development compared with healthy kids, according to neuroscientists at Columbia University Medical Center (CUMC). This slower pruning process results in a surplus of brain synapses — the points where neurons connect and communicate with one another.
The study, published in the journal Neuron, also found that the drug rapamycin (also known as sirolimus) was able to restore normal synaptic pruning and improve autistic-like behaviors in mice, even after symptoms had appeared.