Researchers Have Mapped Where Anxiety and Addiction Live in the Brain, Spawning New Hope for Treatment and Prevention
By Ernie Hood
It’s a “teeny-tiny” brain region that’s about the size of a sunflower seed, and it may be a central point for the impact of chronic stress and its consequences such as anxiety and addiction. It may also represent an exciting new target for prevention and treatment.
It’s called the bed nucleus of the stria terminalis, or BNST for short.
A group of researchers at the Vanderbilt School of Medicine led by Dr. Jennifer Blackford have been focusing their human brain imaging studies on the BNST, and have learned a lot about its functions and structure, building on previous work by others that characterized its role in the neurocircuitry of rodents.
“Physically, the BNST is part of a circuit that modulates the body’s stress response,” said Blackford. “The BNST is in path in the fear circuitry, which we’ve always thought of as being driven by the amygdala, and the reward circuitry, which is largely driven by the nucleus accumbens. It turns out this little extra piece, the BNST, is connected to all of those regions,” she explained.
When it is functioning abnormally, the fear circuit, with its direct connection with the amygdala, can spawn anxiety. When something goes awry with the reward circuit, addiction can be a result. “We think the BNST is involved in both disorders,” said Blackford. “We believe that these critical roles in stress systems, fear systems, and reward systems lead to this risk for addiction and anxiety.”
Beyond Basic Science
According to Blackford, it was quite a technological feat to simply detect and find such a very small brain region and map its circuitry, laying a foundation for future work in that area. “But it also gives an immediate way to start applying knowledge about this circuit to psychiatric disorders,” she noted.
“One thing about the BNST that makes it even more exciting is that it responds differently to drugs than the amygdala, which has been a target for treatment of many anxiety disorders,” said Blackford. She added that some FDA-approved drugs have been shown to affect the BNST in rodents, “so the BNST could be a brandnew target for treatment.” If it can be confirmed that the BNST is altered in some psychiatric disorders, “the very next step could be starting to test the use of some of these medications.” She cautioned, however, that clinical trials for such applications are probably 5-10 years away.
Currently, she and her colleagues are studying the potential role of the BNST in post-traumatic stress disorder and schizophrenia, and they have applied for funding to look at its possible involvement in alcoholism. Using their multi-modal neuroimaging approach, they recently developed a task that allows direct measurement of BNST response. Importantly, the task selectively engages the BNST and not the amygdala. “We’re looking at uncertainty: Uncertain things happening in your life creates risk for addiction and creates anxiety, so this task allows us to measure BNST function in the context of uncertainty,” she said.
Molding behaviors to prevent later problems
With children who exhibit early warning signs of anxiety or depression, Blackford said that behavioral interventions may be the safest and most effective treatment approaches, and her lab is working to develop modalities that will prevent development of the psychiatric disorders often seen in adolescence or adulthood.
Taking advantage of the brain’s plasticity, the idea is to retrain the BNST or other regions (such as the prefrontal cortex) to correct defects in the fear or reward circuits.
Blackford is optimistic and enthusiastic about the ramifications of her group’s work. “It’s a very exciting field, and I think it has really direct treatment implications,” she said. “That’s part of the focus of my lab, not just to discover things that are interesting to know, but things that can actually, in the foreseeable future, have an impact on people who are suffering with these disorders.”