Statistics in 2017 said about 284 million people worldwide experienced an anxiety disorder that year. Data suggest that approximately 12 million adults experience a year of post-traumatic stress disorder (PTSD) in the United States. One of the primary causative factors among these mental health conditions is excessive fear.
Fear is a natural emotion that helps ensure a human or animal responds appropriately to danger. Still, it can become excessive in some individuals and may lead to mental health conditions, including anxiety and PTSD.
In addition, a 2019 study suggested that anxiety disorders could co-occur with alcohol use disorder (AUD). Despite the known facts about fear-based conditions, the mechanisms behind how the brain regulates fear are not well understood.
Dr Mirela Loftus, medical director for Newport Healthcare, says, “It has been known for some time that the fear pathway in the brain entails connections between the hippocampus, the place that helps us build memories; the amygdala, the place that helps process fear and traumatic memories; and the medial prefrontal cortex that acts like the command centre and controls these areas.”
Recent research uncovered evidence on how these brain regions communicate fear — specifically, the pathways in the brain that transmit threat cues to the amygdala. The scientists who conducted the study also suggest these pathways create unpleasant fearful memories.
Now, a new study from researchers at Linköping University, Sweden, may offer more clues as to how these fearful memories are processed and stored in the brain.
The scientists found that reduced levels of an epigenetic enzyme called PRDM2 affect specific genes in the brain, resulting in increased nerve cell activity between the frontal lobes and the amygdala.
The researchers suggest this biological mechanism impacts how the brain strengthens and holds onto fear-related memories. Their discovery might also offer insight into the links between anxiety disorders and AUD.