Researchers at the University of Bonn Hospital have demonstrated that the bonding hormone oxytocin inhibits the fear center in the brain, allowing fear to subside more easily.
The study, which appears in the journal Biological Psychiatry, could usher in a new era in the treatment of anxiety disorders, according to the researchers.
The researchers note that significant fear becomes deeply entrenched in memory. For example, following a car accident, a person might become conditioned to feel quite anxious just hearing tires screeching.
Gradually, that person learns that not every screeching tire means danger. This active overwriting of the memory is known as “extinction.”.
“In this process, however, the original contents of the memory are not erased, but instead merely overlaid with positive experiences,” said psychiatrist René Hurlemann, M.D., from the Department of Psychiatry and Psychotherapy of the University of Bonn Hospital.
“If there are dangerous situations once again, the fear, which was believed to have been already overcome, frequently flares up once more.”
Extinction is often used in therapy for anxiety disorders. For example, part of the treatment for a person suffering from a spider phobia is to have them gradually and increasingly come face to face with spiders.
First the patient views photos of spiders and then looks at living examples until finally he holds a tarantula in his hand. This helps the patient realize they do not need to fear the trigger — or the spider, researchers explained.
“However, this can take a very long time, because this confrontation with the fearful situation frequently has to be experienced. In addition, there may be relapses because the original trace of fear is still anchored in the memory,” Hurlemann said.
This is one reason researchers began looking for a way to overwrite fearful memories in a faster and longer-lasting way.
That brought them to oxytocin.
It has been known for a long time that the hormone oxytocin does not just have a bonding effect in the mother-child relationship and in the case of sex partners, but that it is also considered to be anxiolytic, meaning it reduces anxiety.
“Oxytocin actually reinforces extinction: Under its influence, the expectation of recurrent fear subsequently abates to a greater extent than without this messenger,” reported Hurlemann.
For the study, the research team induced fear conditioning in 62 healthy male subjects. In a brain scanner, using video glasses, the men viewed photos. For 70 percent of the images, they received a very brief, unpleasant electrical shock to the hand via electrodes.
“In this way, certain images were associated with an experience of anxiety in the test subjects’ memory,” Hurlemann said.
The scientists used two methods to prove that the pairing of a particular photo and pain was actually anchored in the mens’ brains. The expectation of an electrical shock was demonstrated by increased cold sweat, which was measured via skin conductivity, while the brain scans proved that the fear regions in the brain were particularly active.
Half of the test subjects then received oxytocin via a nasal spray. The rest received a placebo.
Then the extinction phase began. The men were shown the same pictures, but they no longer received electrical shocks.
In the men under the influence of oxytocin, the amygdala, as the fear center in the brain, was overall far less active than in the control group, whereas fear-inhibiting regions were more stimulated, the researchers reported.
Over time, the messenger caused the fear to initially be somewhat greater but then it abated to a far greater extent than without oxytocin.
“Oxytocin initially reinforces the test subjects’ conscious impressions and thus the reaction to the electrical shock, yet after a few minutes, the anxiolytic effect prevails,” explained Hurlemann.
The scientists said they hope that patients with anxiety can be helped more quickly with the aid of oxytocin and that a relapse can be better prevented.
“In addition,” they said, “the hormone likely facilitates bonding between the therapist and the patient, leading to more successful treatment.”
“However, this must first be demonstrated by clinical studies,” he concluded.
Source: University of Bonn