Left and right voters: are there differences in the structure of their brains?

The tonsils in the brains of conservative (right-wing) voters are about the size of a sesame seed, that is, slightly larger than those of progressive (left) voters, according to a study published in the journal Cell Press iScience.

The research, carried out by scientists from the University of Amsterdam (Netherlands), aimed to replicate a previous study published in 2011 and based on 90 university students from the United Kingdom, and whose brain images showed that progressive and conservative voters have differences in their brains.

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On this occasion, the team wanted to verify the results with a larger and more diverse group of participants and, to that end, analyzed MRI brain scans of 928 individuals aged 19 to 26 with education levels and political identities representative of the Dutch population.

The results confirmed that the size of a person’s amygdala is related to their political opinions.

The anatomical differences they observed in the amygdala and anterior cingulate cortex (ACC) changed according to the economic and social ideology of the person, which indicates that the relationships between political ideology and brain structure are “nuanced and multidimensional”, notes the study.

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For Diamantis Petropoulos, first author and researcher at the American College of Greece and the University of Amsterdam, “It was really a surprise that we reproduced the amygdala finding. We didn’t expect it”.

Ideological differences, different brains

As the Netherlands has a multi-party political system, the study also wanted to compare its effect on the brain, in contrast to the two-party system in the United Kingdom, and analyze the ‘ideology’ of the participants from various angles and different socioeconomic issues.

To do this, they gave participants a questionnaire with questions about social and economic identity (how they see themselves on a sliding scale from progressive to conservative, and what political party they identify with), social and economic ideology (what is their stance on different social and economic issues, such as women’s and LGBQT rights, income inequality and benefit sharing).

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As in the original study, The team found an association between conservatism and gray matter volume in the amygdala, although three times weaker than in the original study.

“The amygdala controls the perception and understanding of threats and uncertainty about risk, so it makes a lot of sense that people who are more sensitive to these issues have a greater need for security, something that usually coincides with more conservative political ideas.”Petropoulos stated.

Depends on the political party

The relationship between amygdala size and conservatism also depended on the political party with which the individual identified; For example, participants who identified with the socialist party, which has radically leftist economic policies but more conservative social values, had on average more gray matter in their amygdala than those in other progressive parties.

“The Netherlands has a multi-party system, with different parties representing a spectrum of ideologies, and we found a very nice positive correlation between the political ideology of the parties and the size of that person’s amygdala.”says Petropoulos.

Brain

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Conservatism and gray matter

But unlike the original study, The team found no association between conservatism and lower gray matter volume in the ACC, a brain region involved in error detection, impulse control, and emotional regulation.

The researchers also expanded their analysis to examine possible associations between political identity and other brain regions and found a positive association between gray matter volume in the right fusiform gyrus, a region of the temporal lobe essential for visual and cognitive functions, and economic and social conservatism.

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“These regions have to do with facial recognition, so it makes sense that they are involved when one thinks about political issues, since they often remind us of the political figures who represent the ideology on those issues.”says Petropoulos.

“Just the memory of a politician’s face, for example, could make the fusiform gyrus light up a little”.

The MRIs used in this study only provide information about the anatomy of the different brain regions, But researchers believe that Future work should integrate information about the functional connections between the amygdala and different parts of the brain.

EFE