Brain stimulation helps socially anxious individuals control avoidance behaviors

Researchers have found that applying a specific pattern of mild electrical stimulation to the brain can help individuals with high social anxiety better control their automatic avoidance behaviors. By synchronizing the rhythmic activity between the brain’s cognitive control and movement centers, the treatment improved participants’ ability to override their immediate emotional impulses. The findings from this small study were published in The Journal of Neuroscience.

Social anxiety disorder is characterized by an intense fear of social judgment and a strong urge to avoid situations that might cause distress. This behavioral avoidance brings immediate, temporary relief. However, this same avoidance ultimately maintains the psychological condition by preventing individuals from experiencing the situations and learning that they are actually safe.

Standard treatments like exposure therapy require patients to confront their fears directly. People with severe social anxiety often struggle to override their automatic urge to flee, which can limit the effectiveness of such therapies. Overcoming this pattern requires a psychological mechanism called emotional action control, which is the brain’s ability to suppress automatic reactions and execute a different planned response.

Brain regions coordinate this kind of control by communicating through rhythmic electrical impulses, commonly known as brainwaves. When a person needs to override an automatic behavior, an area responsible for cognitive control called the lateral prefrontal cortex must sync its low-frequency rhythms with the high-frequency rhythms of the sensorimotor cortex. The sensorimotor cortex is the brain region that ultimately plans and executes physical movements.

Prior studies demonstrated that artificially enhancing this synchronization could improve emotional control in people without anxiety. A team of researchers from Radboud University in the Netherlands, led by Sjoerd Meijer and Bob Bramson, wanted to test if this intervention could be adapted for a clinical population. They designed an experiment to see if rhythmic stimulation could help individuals who struggle with intense social anxiety.

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The researchers recruited 49 adults who were screened using the Liebowitz Social Anxiety Scale, a standard clinical questionnaire. Because the participant count was less than 50, this is considered a small study. The research team focused entirely on individuals whose anxiety scores indicated a high likelihood of experiencing daily social anxiety disorder symptoms.

During the experiment, participants lay inside a functional magnetic resonance imaging scanner. This machine tracks blood oxygen levels in the brain to measure dynamic changes in neural activity. Participants held a joystick on their abdomen and viewed images of happy and angry faces on a computer screen.

In the standard version of the task, participants were instructed to pull the joystick toward themselves when they saw a happy face and push it away when they saw an angry face. This instruction aligns with natural human tendencies to approach positive stimuli and avoid negative ones.

In the challenging version of the task, the rules were reversed. Participants had to push the joystick away for happy faces and pull it toward themselves for angry faces. This specific setup forced the participants to exert mental effort to override their automatic emotional impulses to pull away from perceived threats.

While the participants performed these tasks, the researchers applied a technique called dual-site transcranial alternating current stimulation. This noninvasive intervention uses specialized, ring-shaped electrodes placed directly on the scalp. The device delivers weak, oscillating electrical currents designed to mimic and influence the brain’s natural internal rhythms.

The researchers tested three different stimulation conditions. The first was an in-phase condition designed to synchronize the lateral prefrontal cortex and the sensorimotor cortex. The second was an anti-phase condition designed to disrupt their synchronization. The third was a sham condition where the stimulation was turned off almost immediately, serving as a placebo baseline to compare against.

The three stimulation conditions alternated in short blocks of about one minute each. Between blocks, the researchers included pause periods to allow the effects of the previous stimulation to wash out. This ensured that each testing block remained independent of the others.

The researchers found that participants performed better at the task during the in-phase stimulation. They made fewer errors on the challenging, reversed-rule task compared to the baseline sham condition. The anti-phase stimulation did not produce statistically significant performance benefits.

The brain imaging data revealed that the in-phase stimulation successfully strengthened the functional connection between the targeted prefrontal and sensorimotor regions. The electrical intervention also altered the activity of the amygdala, a deep and evolutionarily older brain structure that processes raw emotions like fear and generates automatic defensive reactions.

During in-phase stimulation, the amygdala exerted less influence over the participants’ physical joystick movements. The researchers noted that the intervention seemed to strengthen the brain’s goal-directed pathways. This allowed the prefrontal cortex to successfully compete with the emotional signals coming from the amygdala at the level of physical execution.

The behavioral benefits varied from person to person. The improvements were largest in individuals whose prefrontal cortex showed the strongest physiological response to the electrical stimulation. Participants with the highest self-reported trait anxiety tended to show the strongest neural responses to the intervention.

The brain scans also revealed a difference in how highly anxious participants process control compared to general populations. Rather than using the frontal pole to integrate emotions and goals, the anxious participants relied heavily on the dorsolateral prefrontal cortex. This specific subregion is known for strict rule-based processing, suggesting that anxious individuals must rely on rigid rules to bypass their easily overwhelmed emotional centers.

The study relies on functional magnetic resonance imaging, which tracks blood oxygen levels rather than direct electrical brainwaves. While the researchers manipulated the electrical phases at the scalp, they could not directly measure the resulting changes in the participants’ actual brainwaves during the task.

There was high individual variation in how strongly the participants’ brains reacted to the stimulation. Standardized stimulation protocols may not work equally well for everyone. Individual differences in head anatomy and natural brain activity alter how the electrical currents travel through the skull and interact with neural tissue.

Future research might use individualized computer models to adjust the electrical currents based on a person’s specific brain structure. Scientists also need to investigate whether this type of intervention can produce lasting changes in avoidance behavior in real-world social settings. This might eventually involve testing the stimulation as a tool to enhance traditional exposure therapy.

The study, “Improving Emotion Control in Social Anxiety by Targeting Rhythmic Brain Circuits,” was authored by Sjoerd Meijer, Bob Bramson, Ivan Toni, and Karin Roelofs.