How opioid use disorder affects brain size and function

Individuals with opioid use disorder (OUD) exhibit structural and functional brain alterations, even when no longer using, according to new research. 

Published in RSNA’s journal Radiology, the study highlights several regions of the brain that differ in both size and functional connectivity in patients treated for OUD compared to healthy controls. Experts involved in the study are hopeful that their findings can contribute to better understanding of the behavioral changes in OUD and whether they may be permanent. 

“We are in the midst of an opioid epidemic, with millions affected worldwide and more than 80,000 deaths related to opioid overdoses in the U.S. last year alone,” Saloni Mehta, MBBS, a postdoctoral associate in the Department of Radiology and Biomedical Imaging at the Yale School of Medicine, said in a release. “We need to get a better understanding of the system-level neural alterations associated with opioid use disorder.” 

The study utilized data from the National Institutes of Health-funded Collaboration Linking Opioid Use Disorder and Sleep Study (CLOUDS), which included imaging from structural and functional MR scans. Findings from the opioid group (who were on methadone treatment for OUD) were compared to a group of healthy controls. There were just over 100 patients in the OUD group, and around half were women, who have been largely absent in prior opioid research, the experts noted. 

In the OUD group, lower volumes of the thalamus and right medial temporal lobe of the brain were observed. Compared to men, women in the OUD group showed lower medial prefrontal cortex volume. Conversely, as a whole, the OUD group displayed larger volumes in the cerebellum and brainstem compared to the controls. The OUD group also was found to have greater connectivity in the thalamus, right medial temporal lobe, right cerebellum and brainstem. 

“We observed widespread increases in global connectivity in individuals with opioid use disorder,” Mehta said. “Our goal is to understand better what could have caused these alterations to inform new treatment targets.” 

In the future, the group plans to examine how the observed differences in brain structure and function affect long-term outcomes in OUD. 

In 2022, the Centers for Disease Control and Prevention estimated that more than 6 million people in the United States struggled with OUD. Prior research has indicated that only around 20% of patients with OUD ever receive medication to treat the condition.

The study abstract is available here.