A breakthrough study has, for the first time, generated unique molecular profiles for several psychiatric disorders by examining RNA in brain tissue samples from 700 deceased subjects. The novel research has revealed fascinating physical similarities, and differences, in the patterns of gene expression across disorders including autism and schizophrenia.
The old mind/body binary still persists in some areas of medicine, particularly in the field of psychiatry, which is still primarily driven diagnostically by behavior and not pathology. Despite a strong body of growing research uncovering the genetic foundations for many psychiatric conditions, a team of researchers set out to investigate if it was possible to determine a pathological signature for some disorders of the mind.
The focus of the research was on RNA, the molecules that are key to gene expression, showing when a gene is switched on or off. The team studied 700 cerebral cortical samples from deceased subjects with autism, schizophrenia, bipolar disorder, depression and alcoholism. A large, healthy control group was also included in the study, along with an additional 197 samples from subjects with inflammatory bowel disease (IBD) acting as a non-neural comparison.
One of the strongest overlaps in molecular signatures to come out of the research was identified between schizophrenia and bipolar disorder, suggesting a surprising similarity in two conditions generally considered quite different. Another unexpected finding came in how distinctive both alcoholism and depression were when compared to other disorders.
The results showed that autism shares quite a bit in common with schizophrenia and bipolar disorder, but it also diverges in several key places. Activity in genes specifically related to microglial cells were unique to autistic brains, and one of the researchers on the project is already embarking on further study to see whether manipulating these cells via antibiotics could affect adults with autism.
While the research doesn't offer an immediate path toward a way to pathologically diagnose these disorders, it does fundamentally establish new research avenues to help in understanding and hopefully better treating the conditions.
"We show that these molecular changes in the brain are connected to underlying genetic causes, but we don't yet understand the mechanisms by which these genetic factors would lead to these changes," says Daniel Geschwind, senior author on the study. "So, although now we have some understanding of causes, and this new work shows the consequences, we now have to understand the mechanisms by which this comes about, so as to develop the ability to change these outcomes."
The research was published in the journal Science.
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