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People diagnosed with various mental health disorders can sometimes start engaging in intense political behavior, such as violent protests, civil disobedience and the aggressive expression of political views. So far, however, the link between political behavior and the brain has been rarely explored, as it was not viewed as central to the understanding of mental health disorders.

Researchers at Harvard Medical School, Stanford University School of Medicine and Northwestern University Feinberg School of Medicine recently carried out a study investigating the neural underpinnings of political behavior. Their findings, in Brain, unveil the existence of a brain circuit that is associated with the intensity of people's political involvement, irrespective of their ideology or party affiliation.

"This paper started out as a collaborative effort that focused on learning how to help people better come together and thrive, alongside Stephanie Balters at Stanford," Shan H. Siddiqi, first author of the paper, told Â鶹ÒùÔº.

"We have previously shown that when damaging a brain circuit causes a behavior, therapeutic stimulation to the same circuit may reduce the same behavior. Extending that principle, we went searching for circuits involved in behaviors that might bring people together or drive people apart."

As part of their recent study, Siddiqi, Balters and their colleagues worked closely with Jordan Grafman at Northwestern University. Grafman, who had collected behavioral and neural data from individuals who sustained injuries to specific regions of the brain, suggested investigating people's political behavior.

"As a neuropsychiatrist, I don't often ask patients about their political behavior, but it could be an important change that occurs in neuropsychiatric disorders," said Siddiqi. "If we can find a brain target that modulates political behavior, we can figure out how to help patients increase or decrease that behavior."

Traditionally, when researchers find that damage to a specific brain region is consistently associated with a symptom, they would conclude that the two are casually connected. Yet when it comes to more complex behaviors, such as intense political involvement, associated patterns of brain damage are not immediately apparent.

"For many years the field thus assumed that there was no strong relationship between lesion locations and political behavior," explained Siddiqi.

"We used a newer technique called lesion network mapping, which relies on a large-scale wiring diagram of the human brain known as the human connectome. This allows us to link different brain lesions that might be in different parts of the brain, if they all hit a common brain circuit."

Using these experimental methods, the researchers unveiled a reproducible brain circuit that contributes to political behavior. Rather than influencing people's political views (i.e., whether one is liberal or conservative), this circuit was found to moderate the intensity of political behavior.

"Political ideology and party affiliation did not change with any identifiable pattern of brain damage," said Siddiqi.

"However, regardless of your party affiliation, certain patterns of brain damage might make you more or less likely to express that pre-existing viewpoint. This suggests that your political preferences might be a behavior that you learn from your environment, while the intensity of political involvement might be encoded in specific brain circuits."

The recent work by Siddiqi and his colleagues could soon inspire new studies examining the brain circuit they uncovered and its involvement in political behavior. In the future, these efforts could shed new light on the neural underpinnings of aggressive and problematic political acts, potentially informing the development of targeted interventions addressing these behaviors.

"We are now conducting a large-scale study using transcranial magnetic stimulation (TMS), a tool that can be used to activate or deactivate specific brain circuits," added Siddiqi.

"Participants will receive targeted stimulation to different brain circuits to see what kinds of behavioral changes might occur. We are measuring conventional neuropsychiatric symptoms, but also behaviors like altruism, spirituality, political behavior, and other things that are not conventionally seen as 'symptoms.'

"We hope to develop a comprehensive atlas of which brain circuits can be targeted to help patients with different kinds of behavioral concerns."

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