Study Advances Blood Tests for Psychiatric and Neurological Disorders

The research by investigators at Johns Hopkins Medicine (Baltimore, MD, USA) focused on tracing brain cell-derived mRNAs in the bloodstream. These extracellular vesicles (EVs), which are tiny sacs containing genetic material, are crucial for cell communication and carry messenger RNA (mRNA) from the brain. This method allows for the detection of changes in gene activity within the brain. The team's interest in this area grew from an earlier study that found altered EV communication in pregnant women who developed postpartum depression after childbirth. The latest study used the human placenta as a model to identify 26 placental mRNAs in maternal blood during pregnancy, which disappear after birth. This discovery confirmed that mRNAs from specific tissues, including the brain, are present in EVs in the blood. Utilizing brain organoids derived from stem cells, the researchers demonstrated that EV mRNAs mirror changes within these brain tissues.

Through analysis of brain-specific mRNAs using the Human Protein Atlas and the Genotype-Tissue Expression Project, the researchers identified mRNAs linked to various brain functions and disorders, including mood disorders, schizophrenia, epilepsy, and substance abuse. They also pinpointed 13 brain-specific mRNAs associated with postpartum depression. The study compared mRNAs from cells and EVs in a brain organoid model, finding that while the levels differ, they are correlated. This correlation suggests that it is possible to infer changes in the brain based on EV mRNA levels in the blood. The ultimate aim is to create a simple blood test to detect mRNA level changes related to mental disorders, potentially allowing for early detection of psychiatric emergencies like suicidal behavior. By identifying patients at risk of a psychiatric episode, intervention and prevention of adverse outcomes could be possible. Future research will focus on developing similar tests for conditions like autism spectrum disorder using lab-grown brain samples.

“This is very exciting, because right now, there isn’t a blood marker for disorders affecting the brain,” said Lena Smirnova, Ph.D., an assistant professor at the Johns Hopkins Bloomberg School of Public Health. “Essentially, these conditions are diagnosed by clinical interviews between patients and providers.”

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