How Fear Gets Stuck in (Some) Brains

Quick Hits
Daily brief research updates from the cognitive sciences

Fear is an important human emotion and essential to survival so not to be underestimated. It allows us to avoid life-threatening situations and avoid them again in the future – so fundamentally a good thing. However, we also know that fear can be debilitating, cause inaction, anxiety, and be involved in multiple psychiatric disorders such as PTSD.

We know that fear and threat is primarily, initially at least, processed in a part of the brain called the amygdala. This also controls attention (and also other emotions). This then connects to the frontal regions of the brain. These frontal regions are involved in attention, but also cognition and what we can consider higher, or executive, functions, such as decision making and also controlling our impulses.

This has been known for a long time, but this does not help us understand the precise mechanisms of fear and how in some people it becomes entrenched and leads to severe anxiety disorders.

A group of researchers around Barchiesi of the Linköping University in Sweden have now given us a deeper insight into this and how this happens in a paper just published.

This is where it gets technical – as if the above wasn’t. But let me guide you through this.

Previous research has shown that there is an epigenetic enzyme called PRDM2 that supresses the expression of many genes. Your genes are in constant cycles of activation and deactivation to perform their duties and different enzymes up or down regulate these.

PRDM2 has previously been seen to be lower in those with alcohol dependence and exaggerated stress responses are common in those people. Hence why the researchers zoomed in on this enzyme.

The researchers found that indeed downregulation of PRDM2 increases the consolidation of fear memories in rats by increasing the activity between the frontal lobes and the amygdala. They have also, in addition been able to identify the genes that are downregulated.

This may sound like a bit of technical description, but this is significant step forward in understanding the mechanisms of fear getting stuck in the brain and leading to anxiety disorders.

Unfortunately, there is no know way to upregulate PRDM2 – that I imagine will be the focus of future research.

But for now, let’s at least be grateful for the step forward in understanding the neurobiology of fear.

References

Barchiesi Riccardo, Chanthongdee Kanat, Petrella Michele, Xu Li, Söderholm Simon, Domi Esi, Augier Gaelle, Coppola Andrea, Joost Wiskerke, Ilona Szczot, Domi Ana, Adermark Louise, Augier Eric, Cantù Claudio, Heilig Markus, Barbier Estelle. 
An epigenetic mechanism for over-consolidation of fear memories. 
Molecular Psychiatry, 2022
DOI: 10.1038/s41380-022-01758-6

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