New research from Spain suggests that the gene NTRK3 may be a factor in panic disorder, which is often accompanied by other conditions such as depression or alcoholism, and phobias.
Presence of the gene appears to increase the perception of fear and makes a person overestimate danger causing them to have a heightened sense of alarm and anxiety.
In a study published recently in the Journal of Neuroscience researchers define the specific mechanism for the formation of fear memories which will help in the development of new pharmacological and cognitive treatments.
Panic disorder is a serious condition that affects between 3 and 6 million Americans. People with panic disorder have feelings of terror that strike suddenly and repeatedly with little warning.
Experts have suspected that the disorder has a neurobiological and genetic basis. Now, for the first time, researchers from the Centre for Genomic Regulation (CRG) have found that the gene NTRK3 is a factor in genetic susceptibility to panic disorder.
“We have observed that deregulation of NTRK3 produces changes in brain development that lead to malfunctions in the fear-related memory system,” said Mara Dierssen, head of the Cellular and Systems Neurobiology group at the CRG.
“In particular, this system is more efficient at processing information [that has] to do with fear — the thing that makes a person overestimate the risk in a situation and therefore feel more frightened and, also, that stores that information in a more lasting and consistent manner.”
Different regions of the human brain are responsible for processing this feeling, although the hippocampus and amygdala play crucial roles.
On the one hand, the hippocampus is responsible for forming memories and processing contextual information, which means that the person may be afraid of being in places where they could suffer a panic attack; and on the other, the amygdala is crucial in converting this information into a physiological fear response.
Although these circuits are activated in everyone in warning situations, what the CRG researchers have discovered is that “in those people who suffer from panic disorder there is overactivation of the hippocampus and altered activation in the amygdala circuitry, resulting in exaggerated formation of fear memories,” said Davide D’Amico, co-author of the work.
D’Amico and colleagues found that Tiagabine, a drug that modulates the brain’s fear inhibition system, is able to reverse the formation of panic memories.
Although it had already been observed to alleviate certain symptoms in some patients, “we have discovered that it specifically helps restore the fear memory system,” said Dierssen.
Panic attacks can last several minutes, be sudden and repeated; the sufferer has a physical reaction similar to the alarm response to real danger, involving palpitations, cold sweats, dizziness, shortness of breath, tingling in the body, nausea and stomach pain .
On top of this, they feel chronically anxious about suffering another attack.
This study by the CRG researchers shows how memories resulting from a panic attack are stored is what ultimately ends up producing the disorder, which usually appears between 20 and 30 years of age.
Although it has a genetic basis, it is also influenced by other environmental factors, such as accumulated stress. This is why the authors of the paper consider elevated environmental stress in Spanish society to have led to an increase in the occurrence of these disorders.
Currently, there is no cure for this disease, which is treated with medicines that block the more serious symptoms, as well as with cognitive therapy, which aims to help the person learn to survive the attacks better.
“The problem is that drugs have many side effects and psychotherapy is not really aimed at specific moments in the process of forming and forgetting fear memories.
In our work we have defined a specific creation mechanism for these fear memories that could help in the development of new drugs and, also, in identifying the key moments for applying cognitive therapy,” said D’Amico.
This article first appeared on Psych Central on 2 December, 2013.