Nothing to Fear but Fear Itself by Dr. Scott Gerson
Halloween has traditionally been celebrated by exposing ourselves to scary things.
Witches, skeletons, and ghosts are displayed in our yards to elicit one specific emotion: fear.
Fear is a basic biological process. In their lifetime everyone has experienced it in one form or another, and we are all afraid of different things. From fear of physical things like snakes or wasps to intangible fears like heights and public speaking. Certain clinical diseases such as anxiety and post-traumatic stress disorder (PTSD) are associated with exaggerated fear responses. Fear can shape our lives and can have a very powerful effect on our minds and behaviors, but why do we fear things; especially irrational things like toilets, or bridges, or dryer lint? (all of these are common) Is fear caused only from one’s own experiences or could fear be an inherited trait?
Sometimes fear is learned. We may come across something that conditions us to be afraid either rationally or irrationally. For example, a child who comes into contact with an angry dog at one year of age might be afraid of dogs for a lifetime, although she doesn’t even remember the incident.
Fear produces a stress response which is the result of reactions occurring in the hypothalamus and amygdala—parts of the brain involved with “fight or flight” responses. Depending on the intensity of the response, brain functioning may be altered resulting in abnormal reactions. The associated fear memory can be acute or prolonged causing anxiety, depression, and even PTSD. Many of these disorders have been found to be associated with various epigenetic mechanisms.
But fear is not an entirely bad thing. Although it is sometimes detrimental, fear is also sometimes a biological necessity for survival. A rabbit that is not afraid of a fox might not last as long as the rabbit that is. But why is a rabbit who has never seen a fox afraid of it? If fear is entirely a learned response the rabbit should show no fear towards a fox, but that is not the case. This tells us those fear responses are naturally hardwired into the brains of many species because they are a necessary evolutionary trait. Epigenetics is shining a light on the mechanism of fear.
Epigenetics is the study of gene expression that does not involve changes to the underlying DNA sequence. Every cell in your body contains the exact same set of genes, but “marks” made on genes turn on and off particular genes that dictate cell function. The most common of these marks is the attachment of a simple methyl group (CH3). Epigenetic marks, including methylation, are significantly influenced by environmental factors such as diet and emotions and may be responsible for everything from acne to cancer.
Certain epigenetic factors either inherited from our parents or formed from early life experiences can make a person more or less prone to fear. In a now famous experiment baby mice were removed from their mother’s early on (maternal separation), mimicking what would be a major childhood trauma in human children. Those mice were found to have heightened fear and anxiety as adults as well as altered DNA methylation patterns on stress-response genes such as CB1 and CRF2 in the cortex. These traits were also passed down to the next two generations of offspring despite the fact their offspring were never separated from their mothers!
Similar finding have been documented in children and grandchildren of survivors of human tragedy and trauma including the Dutch Famine of 1944 and the Holocaust. Not surprisingly, children, grandchildren, and great-grandchildren of both of these survivor groups have been shown to have higher sensitivities to stress and fear.
But if you go out tonight and are scared by a ghost jumping out at you from behind a tree, don’t worry about it too much. Normally, a scary or even traumatic event becomes nothing more than a bad memory. The fear you experience during the event usually dissipates in a process called extinction. For example, if the child who was initially afraid of dogs is then exposed to dogs many times without being bitten, she will lose her fear. This is how exposure therapy works for people with phobias.
The problem, though, is that sometimes the brain does not process those memories correctly. When that occurs, panic disorders, anxiety, and PTSD can develop. The National Institute of Mental Health describes PTSD as:
“a disorder that develops in some people who have experienced a shocking, scary, or dangerous event. It is natural to feel afraid during and after a traumatic situation. Fear triggers many split-second changes in the body to help defend against danger or to avoid it. This “fight-or-flight” response is a typical reaction meant to protect a person from harm. Nearly everyone will experience a range of reactions after trauma, yet most people recover from initial symptoms naturally. Those who continue to experience problems may be diagnosed with PTSD. People who have PTSD may feel stressed or frightened even when they are not in danger.”
People with PTSD experience symptoms such as anxiety, flashbacks and can develop depression and symptoms can be debilitating. An estimated 5% or 13 million people suffer from some form of this disorder in their lifetime. Researchers are beginning to find epigenetic characteristics common to people suffering from PTSD. One such candidate is hypomethylation of a gene region called NR3C1-1F, which codes for glucocorticoid receptors in the blood and impacts stress regulation.
But, again, not everyone who experiences fear or trauma develops PTSD and for those that do, it is very likely that we will soon discover how to treat it at its root cause. But be advised, the “treat”-ment is unlikely to be found in that bag of candy you or your kids will be bringing home tonight.