What does the brain of a person with autism look like, and how are any differences in structure related to the symptoms of autism? One scientist wanted to know. As part of his journey through over 2,000 research studies on autism, Dr. James Lyons-Weiler, has observed structural differences between the brains of people with autism and the brains of what some in autism community call “neurotypicals”.
“During learning, the brains of people with autism are trying to function just like everyone else’s brain – it tries to create multiple connections and complex, local, redundant synapses. But due to environmental damage, or intrinsic damage due to any number of mutations, the brain damages itself.”
Dr. Lyons-Weiler describes the process as “microglial excitotoxicity” – something referred to in Science News as “zombie brain cells”.
“The specialized cells normally clear out debris, and are important shepherds of connections during learning. The problem is something keeps them permanently activated – and they destroy dendrites and neural precursor cells, preventing complex connections. The result is a ‘unipolar brain’, which has all sorts of direct consequences we see in autism”.
Lyons-Weiler says the effect can be magnified in people that have both a mutation and environmental damage, and all of this is presented in his new book, “The Environmental and Genetic Causes of Autism”.
People with autism sometimes show perception differences compared to neurotypicals, says Lyons-Weiler, and these differences include superior peripheral vision, and decreased reaction time to seeing movement. But he says that they also can make people with autism more sensitive to light, sound, and touch. He says that the unipolar brain model also explains why autistics sometimes cannot control their motor movements, and can exhibit repetitive motion, such as hand flapping.
“Unconscious or involuntary hand-flapping, finger or foot-tapping is easily understood given the neuroimaging and neurobiology studies in light of the evidence of the unipolar brain structures” says Lyons-Weiler. “Perceptual signals come in too far, and too fast, and can make it all the way to the motor neuron cortex, where they are perceived as signals to perform body movement.”
He predicts that reduction of microglial activation in people with autism will have a positive, but perhaps transient, reduction in the severity of the symptoms, but says that studies are needed. He notes that the set of conditions that lead to microglial activation in autism is different from those in say, stroke, or in traumatic brain injury (TBI).
“Microglial cells are active in autistics permanently, over the lifetime of the person, due to a positive feedback loop. We know that shutting them down during stroke, or TBI, can improve the long-term outcome of those patients. The same types of studies are needed in autism”.
Lyons-Weiler credits other scientists, including Dr. Russell Blaylock, a neurosurgeon, with recognizing the process a decade ago. “It’s only now that the science has been done that shows how specific environmental toxins enter the brain, and start the process, that we can see the link between the specific symptoms. We can also make testable predictions, and test them, such as that shutting down microglia just prior to or for24 hours after learning may be important to teaching children with autism. There is much research to do on the effects of diet on learning. It’s an exciting time for families with loved ones with autism”.
“The Environmental and Genetic Causes of Autism” is due out from Skyhorse Publishing in November, 2016.