A team of scientists that studied almost 150 Vietnam War veterans has found that certain kinds of brain injuries may increase religious fundamentalism.

The researchers at Northwestern University in Illinois found that combat vets who suffered trauma in the ventromedial prefrontal cortex were less willing to accept new ideas and became more extreme in their religious beliefs.

The scientists studied 119 vets with penetrating traumatic brain injuries and 30 with no history of brain injury. Those who suffered injuries to the site reported higher levels of religious fundamentalism compared to those without the lesions.

The finding indicates that “the variation in the nature of religious beliefs are governed by specific brain areas in the anterior parts of the human brain and those brain areas are among the most recently evolved areas of the human brain,” Jordan Grafman of Northwestern University, the study’s corresponding author, told PsyPost.

“Human beliefs, and in this case religious beliefs, are one of the cognitive and social knowledge stores that distinguish us from other species and are an indication of how evolution and cognitive/social processes influenced the development of the human brain,” he said.

Previous research had suggested that the ventromedial prefrontal cortex, which is located in the frontal lobe, was a “critical hub” for belief systems.

Damaging the area appeared to cause an increase in religious fundamentalism by reducing cognitive flexibility – or the ability to update our beliefs in light of new evidence – along with lowering the personality trait of openness, the study found.

Grafman stressed that the results of the study, which was published in the journal Neuropsychologia, were limited.

“For this study, we recruited Vietnam veterans with and without brain injuries,” he told PsyPost. “They were all male American combat veterans. This limits the generalization to other groups of people including women, people from other countries, and people who come from cultures with different primary religious beliefs.

“We need to understand how distinct religious beliefs are from moral, legal, political, and economic beliefs in their representations in the brain, the nature of conversion from one belief system to another, the difference between belief and agency, and the nature of the depth of knowledge that individuals use to access and report their beliefs,” he said.

There are many other factors — both physiological and psychological — that need further study.

“Beliefs have sculpted our behaviors for thousands of years and helped shape the development and sophistication of our brains,” Grafman said. “Such beliefs systems are dependent upon other aspects of our cognitive and social processes and those interactions would be important to understand. For example, how does openness in your personality affect how your form and act upon your beliefs? What about genetic predisposition and its effect upon belief systems?”

“As they say, ‘The devil is in the details,’” he added.