A new study published in Brain suggests that specific brain circuits are linked to how intensely people engage in political behavior, without necessarily influencing their political ideology or party affiliation. Researchers found that damage to areas connected to emotional and cognitive control regions could either heighten or lessen political involvement, with consistent effects seen across both conservative-leaning and liberal-leaning participants.
Political neuroscience research has long indicated that different brain regions are associated with ideological leanings, but it has remained unclear whether brain anatomy plays a role in how actively people participate in politics. Since participation—rather than mere belief—often drives political outcomes, distinguishing the two could help clarify how cognitive and emotional processes shape public life. In addition, investigating the brain networks involved could eventually inform both clinical assessments and broader questions about human social behavior.
“This started out as a collaborative effort focused on learning how to help people better come together and thrive, along with Stephanie Balters at Stanford. We have previously shown that when damaging a brain circuit causes a behavior, therapeutic stimulation to the same circuit may reduce the same behavior,” said study author Shan Siddiqi, an assistant professor of psychiatry at Harvard Medical School and neuropsychiatrist at the Center for Brain/Mind Medicine.
“Extending that principle, we went searching for circuits involved in behaviors that might bring people together or drive people apart. We worked with Jordan Grafman at Northwestern, who had collected a profound set of behavioral data after focal brain damage, and he suggested looking at political behavior.”
“As a neuropsychiatrist, I don’t often ask patients about their political behavior, but I realized I didn’t have a good reason for that – as part of our diagnostic assessments, we ask people about all sorts of different personal behaviors. If political behavior can change in neuropsychiatric disorders, then why aren’t we asking about it? In particular, if we can find a brain target that modulates political behavior, we can figure out how to help patients increase or decrease that behavior.”
To explore these questions, the researchers analyzed data from the Vietnam Head Injury Study, focusing on 124 male United States military Veterans who had sustained penetrating head injuries during combat 40 to 45 years earlier. Participants underwent detailed behavioral testing between 2008 and 2012, including surveys that measured how actively they engaged with politics and how they identified ideologically and by party affiliation. A control group of 35 Veterans who had similar combat experiences but no brain injuries was also included for comparison.
Participants answered questions about their political interest, how often they followed political news, and how frequently they discussed political matters. These responses were combined into a single score representing their intensity of political involvement. Separately, participants rated their political ideology on a scale from extremely liberal to extremely conservative, and their party affiliation from strongly Democratic to strongly Republican.
The researchers employed a technique called lesion network mapping, which links damaged brain areas to broader networks of brain connectivity. By analyzing the relationships between each participant’s brain lesion and their political behavior, the team could determine whether certain patterns of brain injury corresponded with changes in political involvement.
The findings revealed that damage to specific brain circuits was associated with political intensity but not with political ideology or party affiliation. Lesions that disrupted connections to the left dorsolateral prefrontal cortex and the posterior precuneus were associated with more intense political involvement. In contrast, lesions that disrupted connections to the amygdala and anterior temporal lobe were associated with reduced political involvement. These effects were seen across participants regardless of whether they leaned conservative or liberal.
“While most people have not sustained brain injuries akin to those experienced by the veterans in the study, our findings tell us what neural circuits are at play for the population at large,” said senior author Jordan Grafman, professor of physical medicine and rehabilitation at Northwestern University Feinberg School of Medicine and director of brain injury research at Shirley Ryan AbilityLab.
Importantly, political ideology—whether someone leaned left, right, or moderate—did not show a significant link to any specific brain region or network. Neither did party affiliation. This suggests that the brain areas identified are connected to how strongly individuals act on their political beliefs rather than which beliefs they hold.
“We tend to assume that something in your brain affects your political views, but we clearly found no brain circuit that makes you more liberal or more conservative,” Siddiqi told PsyPost. “Political ideology and party affiliation did not change with any identifiable pattern of brain damage. 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. We hope that this helps us find common ground – even when people have different political beliefs, they might be more similar than they think.”
The study’s results echo findings from earlier research on religious fundamentalism. In that work, brain lesions were found to increase rigid, fundamentalist religious beliefs by disrupting a specific brain network, particularly in the right hemisphere. Damage to areas involved in flexible thinking, reasoning, and social judgment appeared to make individuals more prone to absolute and unwavering belief systems. Similarly, in the present study, damage to brain networks involved in cognitive control and emotional regulation was linked to greater or lesser political engagement, depending on the location of the injury.
Both studies suggest that damage to certain networks can influence the style or intensity of belief-related behavior, even if the content of those beliefs—whether religious or political—remains rooted in prior views. Rather than making someone liberal or conservative, brain injuries appear to amplify or suppress how strongly people express and act on their existing opinions.
While the study provides strong evidence linking brain circuitry to political involvement, it has several limitations. All participants were older male veterans, many of whom were more conservative than the general population, which could affect how the findings apply to other groups. The political assessments were also based on participants’ recollections of their beliefs and behaviors before their injuries, which introduces the possibility of memory biases.
“This study was done in military veterans who served in Vietnam,” Siddiqi noted. “In one sense, this was an advantage because it allowed us to control for some variables, ensuring that results weren’t driven by vastly different age groups, professional backgrounds, etc. On the other hand, it means that the results may not fully translate to other populations, so future studies are still needed on this topic.”
Another limitation is that brain lesions, by nature, are not uniformly distributed across participants, and it is impossible to assess behavior before the injuries occurred. While the study controlled for factors like age, education, and cognitive aptitude, unmeasured variables might still have influenced the results.
The researchers also caution that while lesion network mapping helps reveal associations between brain networks and behavior, it does not establish direct causality. Brain stimulation studies targeting these networks would be needed to test whether manipulating activity in these regions can actually change political involvement.
“Current political behavior was compared to a recollection of pre-lesion political behavior,” Siddiqi explained. “That recollection may be inaccurate. We’re now trying to address this by measuring political behavior before and after focal brain stimulation in patients with various psychiatric disorders.”
“Overall, the goal is to identify brain circuits that may be used to help people who seek to modify behaviors that are not classically seen as ‘symptoms’ of a disorder. We are now doing a large-scale study using transcranial magnetic stimulation, a tool that can be used to activate or deactivate specific brain circuits. Participants 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,” Siddiqi said. “We hope to develop a comprehensive atlas of which brain circuits can be targeted to help patients with different kinds of behavioral concerns.”
The study, “Effects of focal brain damage on political behaviour across different political ideologies,” was authored by Shan H. Siddiqi, Stephanie Balters, Giovanna Zamboni, Shira Cohen-Zimerman, and Jordan H. Grafman.
