[It’s commonly believed that] fear is a more basal response to an immediate threat thought to be controlled by the amygdala, while anxiety, linked to a part of the brain known as the bed nucleus of the stria terminalis, or BNST, plays out over time and doesn’t always stem from obvious danger.
Scientists are now challenging the belief that the two emotions are segregated in the brain. A study published September 21 in The Journal of Neuroscience demonstrates that when people are subjected to a certain threat meant to prompt fear or an uncertain threat that evokes anxiety, their brains seem to react the same, calling upon both the amygdala and the BNST in their response. While fear and anxiety are distinct emotional states, it appears their underlying neural circuitry is shared.
The findings have potential implications for how scientists diagnose and treat mental health disorders. The amygdala-fear/BNST-anxiety binary has been integrated in the National Institute of Mental Health’s guidelines for standardizing the study of mental health disorders… By treating fear as the domain of the amygdala while segregating anxiety to the BSNT, [the Research Domain Criteria] may be unintentionally obfuscating their dual involvement in both emotional states.
Rather than treating fear and anxiety as two different systems, [neuroscientist Alexander] Shackman says, “there’s a reasonable chance that one kind of intervention would actually hit both and help with both.”