A new study has reignited the debate over whether political ideology is linked to brain structure.

The research, published in the journal iScience, offers a more nuanced view than earlier findings, which suggested that conservatives have larger amygdalas — the brain’s fear center — while liberals possess larger anterior cingulate cortices, an area involved in conflict detection.

The study, led by researchers Diamantis Petropoulos Petalas, Gijs Schumacher, and Steven Scholte, analyzed brain scans from nearly 1,000 Dutch adults, making it the largest analysis to date on the neurological basis of political beliefs.

“We find a very nice positive correlation between the parties’ political ideology and the amygdala size of that person,” Mr. Petropoulos Petalas, a political psychology and neuroscience researcher from the American College of Greece, said in a press release.

“That speaks to the idea that we’re not talking about a dichotomous representation of ideology in the brain, such as Republicans versus Democrats as in the US, but we see a more fine-grained spectrum of how political ideology can be reflected in the brain’s anatomy,” he said.

Utilizing advanced brain imaging techniques, the team examined gray matter volume in key brain regions, including the amygdala and the anterior cingulate cortice. Additionally, they collected extensive data on participants’ political views, moving beyond simple liberal-conservative labels to investigate economic and social ideologies separately.

The results showed a small correlation between amygdala size and conservatism, though the effect was significantly weaker than previously reported. Importantly, no link was found between anterior cingulate cortice volume and liberal beliefs, failing to replicate a key finding from the original study.

The study also explored other brain regions, finding hints of a relationship between ideology and the fusiform gyrus, an area involved in face and object recognition. However, these results were not consistent across all analyses, underscoring the complexity of the issue.