Traumatic stress associated with smaller brain region

Adults with posttraumatic stress disorder (PTSD) have smaller cerebellums, according to new research from a Duke-led brain imaging study.

The findings, published in the journal Molecular Psychiatry, have prompted Huggins and her lab to start looking for what comes first: a smaller cerebellum that might make people more susceptible to PTSD, or trauma-induced PTSD that leads to cerebellum shrinkage.

The cerebellum, a part of the brain well known for helping to coordinate movement and balance, can influence emotion and memory, which are impacted by PTSD. What isn’t known yet is whether a smaller cerebellum predisposes a person to PTSD or PTSD shrinks the brain region.

“The differences were largely within the posterior lobe, where a lot of the more cognitive functions attributed to the cerebellum seem to localize, as well as the vermis, which is linked to a lot of emotional processing functions,” said Ashley Huggins, Ph.D., the lead author of the report who helped carry out the work as a postdoctoral researcher at Duke in the lab of psychiatrist Raj Morey, M.D.

Huggins, now an assistant professor of psychology at the University of Arizona, hopes these results encourage others to consider the cerebellum as an important medical target for those with PTSD.

“If we know what areas are implicated, then we can start to focus interventions like brain stimulation on the cerebellum and potentially improve treatment outcomes,” Huggins said.

A grapefruit-sized lump of cells that look like it was clumsily tacked underneath the back of the brain as an afterthought, the cerebellum is best known for its role in coordinating balance and choreographing complex movements, like walking or dancing. But there is much more to it than that.

“It's a really complex area,” Huggins said. “If you look at how densely populated with neurons it is relative to the rest of the brain, it's not that surprising that it does a lot more than balance and movement.”

Dense may be an understatement. The cerebellum makes up just 10% of the brain’s total volume but packs in more than half of the brain’s 86 billion nerve cells.

Reference: Traumatic stress associated with smaller brain region; Molecular Psychiatry, DOI: 10.1038/s41380-023-02352-0