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FEAR ON THE BRAIN

Writer's picture: Dr. Elsie ChengDr. Elsie Cheng







We often think of fear as a temporary state. It is an emotional and physiological reaction to an external stimulus that usually subsides once the stimulus ends. However, certain types of fear, namely prolonged or life-threatening, can cause permanent changes in our brains. This is why Post Traumatic Stress Disorder can be such a difficult disorder to treat.

 

The fear response starts in a region of the brain called the amygdala. When triggered, other areas of the brain are activated in order to prepare us for fight or flight, i.e. Motor functions. It also triggers the release of stress hormones and our sympathetic nervous system. Ultimately, making us more efficient at times of danger: muscles grow due to increased heart rate and breathing and gastrointestinal system slows down.

 

However, a different part of the brain called the hippocampus, which is closely connected to the amygdala along with the prefrontal cortex mitigate the fear by interpreting the threat in its context. For example, if you encountered a shark in open waters vs. a shark in an aquarium, your experience of fear would vary significantly given the context. This is because the hippocampus and the prefrontal cortex judge the context and then dampen the amygdala’s fear response. Generally speaking, this neurophysiological process is rather straightforward when we are talking about isolated and mild to moderate fear events. When we are discussing prolonged or life-threatening events, that is altogether a different story.

 

Researchers from the Tulane University School of Science and Engineering and Tufts University School of Medicine found that the stress neurotransmitter norepinephrine, also known as noradrenaline, facilitates fear processing in the brain by stimulating inhibitory neurons in the amygdala to generate a repetitive bursting pattern of electrical discharges. This is particularly the case when there is persisting fear, or an extreme amount of fear being triggered. This bursting pattern of electrical activity changes the frequency of brain wave oscillation in the amygdala from a resting state to an aroused state that promotes the formation of fear memories.

 

This changes the electrical discharge pattern in the amygdala, which transitions the brain to a state of heightened arousal that facilitates memory formation and fear memory. Because of the neurophysiological alterations, patients with PTSD often struggle with re-experiencing of traumatic events and hyper-vigilance.

 

Disorders of anxiety and fear include phobias, social phobia, generalized anxiety disorder, separation anxiety, PTSD and obsessive-compulsive disorder without appropriate treatment can become chronic and debilitating. Without understanding the neurophysiological basis of fear, it’s difficult to appreciate how to really help individuals that are often paralyzed by their fears. Treating anxiety disorders such as PTSD is not as simple as enlisting them in talk therapy. Rather, it is considering how best to rewire their brains from the heightened state due to the electrical discharges and the neurophysiological changes. The best form of treatment is conjunctive therapy with behavioral, cognitive and neurochemical (medications) approaches. Combined, these could help the individual normalize the brain function.

 

In my practice, I encounter patients regularly that have been involved in catastrophic injuries, varying from construction site accidents to transit accidents. What I often see is along with their head injuries, patients are often dealing with the residual effects from the fear/anxiety related to the accident itself. Thus, it is important that we take note of the effects of fear on the brain as these can often cause insidious problems that compound patient recovery.

 

 

 

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