Nov. 2 (UPI) -- Brain changes in people with autism are more far-reaching than previously thought, occurring throughout the cerebral cortex rather than being confined to certain areas thought to affect social behavior and language.
That's according to a new study -- lasting more than a decade and led by the University of California-Los Angeles -- that explored how autism spectrum disorder affects the brain at the molecular level.
The researchers found changes in "virtually all" of the 11 cortical regions of the brain that they analyzed, including "higher critical association regions" involved in functions such as reasoning, language, social cognition and mental flexibility, as well as primary sensory regions, a news release said.
The findings were published Wednesday in the journal Nature.
Neurological disorders such as Alzheimer's disease and Parkinson's disease have well-defined pathologies, but autism does not, which makes it difficult to develop more effective treatments, the scientists said.
"We now finally are beginning to get a picture of the state of the brain, at the molecular level, of the brain in individuals who had a diagnosis of autism. This provides us with a molecular pathology ... [and] provides a key starting point for understanding the disorder's mechanisms, which will inform and accelerate development of disease-altering therapies," Dr. Daniel Geschwind, the study's corresponding author said in the release.
In 2011, Geschwind, who is the Gordon and Virginia MacDonald Distinguished Professor of Human Genetics, Neurology and Psychiatry at UCLA, led the first effort to identify autism's molecular pathology by focusing on two high-cognition brain regions, the temporal lobe and frontal lobe.
For the new study, the investigators examined gene expression in 11 cortical regions of the brain by sequencing RNA from each of the four main cortical lobes.
The scientists compared brain tissue samples obtained after death from 112 people with autism spectrum disorder against healthy brain tissue.
Each profiled region showed changes, but the largest drop off in gene levels was in the visual cortex and the parietal cortex, which processes information such as touch, pain and temperature, the release said.
The researchers explained this may reflect the "sensory hypersensitivity" that is frequently reported in people with autism.
The investigators also found strong evidence indicating that RNA changes in the brain are likely the cause of autism rather than a result of the condition.
Next, the researchers aim to determine whether they can use "computational approaches" to develop therapies based on reversing the gene expression changes in the brain that they have found in people with autism, Geschwind said in the release.