Study links overthinking to 'constant communication' between brain's fear-centre, social behaviour

Overthinking could be related to the constant back-and-forth between the brain's fear-processing centre or amygdala and the region governing social behaviour, according to a new study.

Reasoning about another person's thoughts and intentions is a core aspect of social cognition and relies on one's social cognitive network. It connects brain regions working together to support a person's ability to understand and interact with others.

"Previous studies have found co-activation of the amygdala and social cognitive network, but our study is novel because it shows the communication is always happening," senior author Rodrigo Braga, an assistant professor of neurology at Northwestern University, US, said.

The constant back-and-forth is possibly why moments after leaving a party, one is suddenly filled with intrusive thoughts such as ‘Did they think I talked too much?’ or ‘Did my joke offend them?’, the researchers said.

To better understand how humans evolved to become so skilled at thinking about what's happening in other peoples' minds, the team looked at functional magnetic resonance imaging (fMRI) brain scans of six people. The fMRI measures brain activity by detecting changes in blood oxygen levels.

"The results suggest that social cognitive functions emerge through coordinated activity between internal circuits of the amygdala and a broader distributed association network and indicate the medial nucleus (located within the amygdala) may play an important role in social cognition in humans," authors wrote in the study published in the journal Science Advances.

This link to the amygdala helps shape the function of the social cognitive network by giving it access to the amygdala's role in processing emotionally important content, the researchers said.

The findings could have implications for treating psychiatric conditions, such as anxiety and depression, they said. Both anxiety and depression involve amygdala hyperactivity, which can contribute to producing excessively emotional responses and impaired emotional regulation, author Donnisa Edmonds, a PhD candidate of neuroscience at Northwestern University, said.

The researchers explained that currently, someone with either condition could receive deep brain stimulation for treatment, but since the amygdala is located deep within the brain — directly behind the eyes — it means having an invasive surgical procedure.

Transcranial magnetic stimulation (TMS), which uses magnetic fields to arouse neurons in the brain, is a much less-invasive procedure and could benefit from the study's findings to improve treatment, they said.

"Through this knowledge that the amygdala is connected to other brain regions — potentially some that are closer to the skull, which is an easier region to target — that means people who do TMS could target the amygdala instead by targeting these other regions," Edmonds said.