Genetics of Personality: Fear

Fear is a useful emotion, which can help to keep a person away from overly dangerous situations. But too much fear can be paralysing, and can put the person in much more danger than he might have faced otherwise.

Scientists have begun to look at the neural mechanisms of fear, and the genetic underpinnings behind these brain mechanisms.

As many as one fourth of all Americans will suffer from potentially debilitating anxiety, panic disorders, animal phobias and post-traumatic stress reactions at least once in their lives. These disorders cause not only mental anguish but a variety of real physical symptoms, including localized pain. As with other forms of behavior, we would like to know to what extent fear is learned from environmental experience and to what extent it is influenced by our genetic makeup.

Specific genes associated with such behavior are currently being identified in laboratory mice. Not surprisingly, many of the genes associated with fear or the lack of it encode neurotransmitters or their receptors. These are the molecules within the brain responsible for chemical communication between nerve cells; they ultimately underlie all behavior. __Sciam

The genetically-influenced neural mechanisms of fear appear to be closely related to the genetically-influenced neural mechanisms of violence. Genes that influence neurotransmitter levels — such as the MAO genes and COMT genes, along with genes for neurotransmitter receptors and transporters — appear to affect an individual’s susceptibility to fear conditioning, at the same time that they affect susceptibility to violent behaviours.

Serotonin is a brain chemical involved in mood regulation. The serotonin transporter, which is the target of selective serotonin reuptake inhibitors (SSRI) used to treat anxiety and depression, harbors a common polymorphism in its gene. This polymorphism can come in two different versions that differ in their length. The shorter version of the gene leads to less serotonin being cleared away and is also associated with higher neuroticism scores and anxious behavior. The COMT enzyme is involved in breaking down dopamine, a brain chemical important for learning, motivation and seeking rewards. A specific polymorphism in this gene results in higher levels of extracellular dopamine in the prefrontal cortex, leading to enhanced working memory but also greater levels of anxiety. SciD

The particular areas of the brain involved in fear and anxiety are many, but researchers are currently focusing on parts of the limbic system such as the amygdala, and particular areas of the pre-frontal cortex.

…individual differences in amygdala and vmPFC function are independently associated with vulnerability to anxiety, with the amygdala potentially influencing the development of cue-specific fears (or phobias) and the vmPFC impacting the ability to downregulate both phasic fears and generalized anxiety. , SciD

The number of possible genetic combinations of alleles influencing behaviour — as well as the range of possible epigenetic modifications — is huge.

A global map of homicide rates by country reveals some interesting regional trends. These trends suggest a number of scientific hypotheses relating to genes and behaviour which should be tested — but which for reasons of political correctness will probably be avoided by government funded science and by the mainstream media.

The government and the media appear to wish the public to behave as helpless sheep, protected by the (corrupt and unreliable) government and guided by the (highly biased and corrupt) media.

The public, on the other hand, is a highly heterogeneous mix of genes and neural mechanisms. That has always been the problem for corrupt power structures that wish to dominate every aspect of the citizens’ lives.

Dangerous children are only likely to make the jobs of these corrupt institutions even harder.

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