A recent study at the University of North Carolina at Chapel Hill has uncovered an unexpected mechanism in the brain that may explain why individuals recovering from drug addiction frequently experience relapse.
Chronic drug use alters the brain's structure significantly. By using a rodent model of cocaine consumption, UNC researchers discovered that during abstinence, immune cells called microglia actively begin to prune parts of astrocytes, critical support cells in the brain. This cellular damage heightens drug-seeking behaviors, but when scientists intervened to prevent microglia from removing astrocyte components, they observed a reduction in relapse behaviors.
The research is published in the journal Cell Reports.
Cell Reports"Our findings indicate that immune cells in the brain can induce drug cravings by degrading support structures essential for maintaining balanced neural circuits," said Kathryn Reissner, lead investigator and professor of psychology and neuroscience at UNC-Chapel Hill. "By safeguarding these connections, we might be able to reduce relapse risks for those recovering from addiction."
Astrocytes play a critical role in regulating the brain's reward system. While previous research had revealed that these cells shrink following cocaine use, the underlying cause remained unknown until now. This study is the first to illustrate that the brain's immune response is responsible and that this process directly influences relapse risk.
"Traditional addiction treatments have primarily focused on neurons; however, our findings demonstrate that targeting the brain's immune system could offer an entirely new approach in combating addiction and preventing relapse," said Anze Testen, co-lead researcher and former graduate student at UNC-Chapel Hill. "This is a promising step toward therapies that preserve brain health during recovery."
The research team suggests their findings could reshape how we treat addiction in the future. Instead of focusing solely on neurons, emerging treatments might aim to protect astrocytes and limit harmful immune responses in the brain.
"This is an exciting example of fundamental science uncovering hidden mechanisms of disease," said Jonathan VanRyzin, co-lead researcher and postdoctoral fellow at UNC-Chapel Hill. "By understanding how microglia and astrocytes interact following drug use, we're closer to developing targeted strategies to help individuals stay drug-free."
Beyond cocaine addiction, the study highlights a broader implication: neuroimmune interactions may play a pivotal role in how the brain adapts following substance abuse. The researchers intend to explore whether similar processes occur in humans diagnosed with substance-use disorders.
Tania Bellinger, co-lead researcher and graduate student at UNC-Chapel Hill, remarked that this work opens up new molecular targets for therapy. "Future treatments might be able to inhibit the brain's immune system from damaging healthy cells, ultimately aiding people in maintaining recovery."