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Saturday, September 13, 2014

Studies Implicate Early Injury to Cerebellum as Major Cause of Autism

From Autism Speaks' Science Digest

September 9, 2014

Injury to small brain region during pregnancy or birth may disrupt development of important cross wiring to other brain regions.

A new review of research suggests that a small brain region largely known for coordinating movement could play the largest nongenetic role in autism’s development.

A team of Princeton neuroscientists present their idea – based on a new interpretation of extensive autism research – in the journal Neuron.

The cerebellum — an area located in the lower rear of the brain — is best known for processing information from the senses and coordinating movement. Though it makes up just 10 percent of the brain, it contains nearly half of all the brain’s nerve cell connections.

As far back as 1985, research has suggested that autism commonly involves abnormalities in the cerebellum. But the role that these differences play in autism has remained mysterious.

“While this new paper doesn’t present new study data, the authors present the intriguing idea that abnormalities in the cerebellum can affect not only how the brain functions, but also how it develops,” comments developmental pediatrician Paul Wang, Autism Speaks senior vice president and head of medical research.


“These theories about the cerebellum’s role in autism underscore that different regions of the brain are constantly interacting, and that communication among the different regions of the brain is critical to its function.”Princeton University researchers offer a new theory that early injury to the cerebellum disrupts brain processing in ways that can lead to autism.

Cerebellum Injury and Autism Risk

In their new interpretation, the Princeton researchers note studies showing that babies who sustain injury to the cerebellum before or during birth have a starkly higher risk of autism. (See graph at right.)

They also reference studies showing that the cerebellum is the most frequently disrupted brain region in people with autism.

Further, they write that recent research suggests that the cerebellum plays a particularly crucial role in the prenatal development of brain connections to and between other areas of the brain.

They propose that cerebellar injury causes disruptions in how other areas of the brain develop the ability to interpret external stimuli and organize internal processes.

"It’s well known that the cerebellum is an information processor,” says study co-author Samuel Wang. “Our neocortex [the part of the brain that controls higher thought] does not receive information unfiltered. There are critical steps that have to happen between when external information is detected by our brain and when it reaches the neural cortex…. In autism, something in that process goes wrong and one thing could be that sensory information is not processed correctly in the cerebellum."

Dr. Wang of Autism Speaks (no relation to Samuel Wang) concurs with the authors in concluding: “We need to continue studying how cerebellar dysfunction affects other parts of the brain and how such dysfunction might be improved with therapy and new medicines.”

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