Neuroimaging study reveals different brain mechanisms in anxious vs. non-anxious individuals

Anxious individuals use different brain regions and neural mechanisms to regulate their emotional action tendencies compared to non-anxious individuals, according to new neuroimaging research published in Nature Communications. The findings shed light on the neural underpinnings of emotional control in anxiety and contribute to a better understanding of how anxiety affects decision-making and behavior in social situations.

The motivation behind the study was to investigate how anxious individuals make decisions in socially challenging situations and how their brain activity differs from that of non-anxious individuals. The researchers aimed to understand the neural mechanisms underlying the difficulties faced by anxious individuals in controlling their emotional responses and behaviors.

“We study approach and avoidance behavior, and how people control automatic avoidance actions to threat,” said study author Bob Bramson, a postdoctoral researcher at the Behavioral Science Institute and the Donders Centre for Cognitive Neuroimaging at the Radboud University Nijmegen. “We do this because we think avoidance is one of the main maintaining factors of anxiety related disorders. If someone is anxious and always avoids those situations they never learn from exposure that those situations are not threatening. This makes control over emotional actions (and difficulties in control) of key interest in understanding anxiety disorders.”

Anxiety disorders are known to involve excessive avoidance of feared situations, which hampers the ability to learn through exposure and adapt to emotional challenges. The researchers were particularly interested in exploring how the brain’s prefrontal cortex, specifically the lateral frontopolar cortex (FPl), plays a role in regulating emotional action tendencies and whether this process is different in people with anxiety.

To conduct the study, the researchers employed a combination of neuroimaging techniques and experimental tasks to analyze brain activity, brain structure, and neurochemical properties of the FPl in both anxious and non-anxious participants. They hypothesized that the FPl’s function and connectivity might explain the altered control of emotional action tendencies in individuals with anxiety.

The researchers recruited participants from Radboud University, including 52 high-anxious individuals and 44 non-anxious individuals. The study participants underwent several neuroimaging sessions on different days, involving structural magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS) scans to measure neurochemical properties, diffusion weighted imaging (DWI) to examine brain connectivity, and functional MRI (fMRI) scans to observe brain activity during emotional action control tasks.

During the fMRI sessions, participants engaged in a social-emotional approach-avoidance task. They were presented with emotional faces and were instructed to respond by either approaching or avoiding the faces, depending on the emotional valence and the task instructions. The researchers designed congruent and incongruent trials, requiring participants to override their automatic action tendencies.

“Our trial subjects were shown happy and angry faces and had to first move a joystick towards the happy face and away from the angry face,” Bramson explained. “At a certain point they had to do the reverse: move towards an angry face and away from a happy face. This demands control over our automatic tendency to avoid negative situations.”

Both anxious and non-anxious participants performed similarly in the emotional action control task. There was a slightly higher rate of correct responses in the congruent condition (approaching happy and avoiding angry faces) compared to the incongruent condition (approaching angry and avoiding happy faces), indicating that participants were more accurate when their automatic action tendencies matched the task instructions.

However, the researchers found that anxious participants exhibited differences in the functional, structural, and neurochemical properties of the FPl. Specifically, they had a more excitable FPl, as indicated by a higher GABA/Glx ratio, and stronger connectivity between the FPl and the amygdala, a region involved in processing emotions, especially fear and anxiety.

“The study was initially focused at regions we knew contributed to emotion control in healthy individuals, so we assumed that anxious people would recruit the same regions,” Bramson said. “It was surprising that this region was more strongly connected to other areas often associated with emotion, and that it was overexcitable.”

Anxious participants also showed a shift in neural activation compared to non-anxious participants during the emotional action control task. While non-anxious individuals predominantly activated the FPl, anxious individuals relied more on other regions, specifically the dorsolateral prefrontal cortex (dlPFC) and the anterior cingulate cortex (ACC), to achieve emotional control.

The increased activity observed in the dlPFC of anxious individuals might serve as a compensatory mechanism to counter the altered FPl function.

“The key takeaway is that people with high anxiety seem to recruit different brain areas for controlling emotional behavior,” Bramson told PsyPost. “This is likely because the areas that are involved in this control in healthy people receive too much emotional information and are too excitable, making them unable to adequately control emotional actions. This might explain why anxious individuals experience difficulties with emotion control in situations they find threatening.”

But the study, like all research, includes some caveats. The high-anxious group included 39 women and 13 men, while the non-anxious group included only men. This could raise questions about the generalizability of the findings to females and limit the ability to draw definitive conclusions about gender differences in the neural mechanisms described. But the researchers don’t believe that this undermines the significance of the observed findings.

“I do not think this makes a difference, because we have not observed differences between males and females before in the same type of studies, but it might be something that needs to be excluded in a follow-up,” Bramson explained.

“A next question is whether we can improve therapy based on this knowledge. We are currently finishing an article in which we show that we can use electrical brain stimulation to improve emotion control in anxious individuals. I anticipate that article to be available as a preprint this week.”

The study, “Anxious individuals shift emotion control from lateral frontal pole to dorsolateral prefrontal cortex“, was authored by Bob Bramson, Sjoerd Meijer, Annelies van Nuland, Ivan Toni, and Karin Roelofs.

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