September 28, 2012
Fear Difficult To Remove In Adolescents
Connie K. Ho for redOrbit.com — Your Universe Online
Researchers from Weill Cornell Medical College recently discovered that fear is difficult for teenagers to remove, as they may feel a strong sense of threat even when the danger is gone. It is possible that stress and anxiety is highest at this time and the study is the first to examine “fear acquisition” and “fear extinction learning” in the brains of mice, which are somewhat similar to the neural networks of humans. The study showed that, when the brain of a teenager has been activated, it has a hard time limiting an emotional reaction to the threat.In particular, scientists believe that after acquiring fear, it can be difficult to eliminate in some children. Once the fear is removed, adults and adolescents do not have the same issues in learning. The findings were recently published in the online edition of Proceedings of the National Academy of Science (PNAS).
"This is the first study to show, in an experiment, that adolescent humans have diminished fear extinction learning," explained the study's lead author Dr. Siobhan S. Pattwell, a postdoctoral fellow at the Sackler Institute for Developmental Psychobiology at Weill Cornell, in a prepared statement. "Our findings are important because they might explain why epidemiologists have found that anxiety disorders seem to spike during adolescence or just before adolescence. It is estimated that over 75 percent of adults with fear-related disorders can trace the roots of their anxiety to earlier ages."
According to researchers, the prefrontal cortex of the brain has altered plasticity during childhood that has difficulty confronting fear.
"This study is the first to show activity, at the synaptic level, for both fear acquisition and fear extinction -- and we find that while these areas function well in both younger and older mice, neurons involved in fear extinction are not as active in adolescent mice," remarked Dr. Francis Lee, a professor of pharmacology and psychiatry at Weill Cornell Medical College, in the statement. "If adolescents have a more difficult time learning that something that once frightened them is no longer a danger, then it is clear that the standard desensitization techniques from fear may not work on them. This new knowledge about the teenage brain's synaptic connections not responding optimally will help clinicians understand that the brain region used in fear extinction may not be as efficient during this sensitive developmental period in adolescents."
Withheld during years of evolution, fear learning is a process that is highly adaptive and based on past experiences with danger. Fear can play a role in different types of anxiety disorders, such as post-traumatic stress disorder (PSTD). There are currently treatments that were created to help people realize a possible threat. These therapies can also treat different fears, such as fear of flying, adolescent anxiety about beginning school, or wartime PTSD. Interesting enough, more and more anxiety disorders are found in children and the study focused on exploring whether extinction-based exposure therapies were helpful for the patients.
The study included a group of volunteers, ranging from children to adults, who were asked to look at a computer screen with a pattern of yellow or blue square images while wearing headphones and skin sweat meters. One of the squares would have a loud noise and if the participant showed fear of the noise, the scientist could measure it with the skin sweat meter. The group was brought in for a follow-up, where there was a pattern of yellow or blue squares but no loud noise.
"But teenagers didn't decrease their fear response, and maintained their fear throughout subsequent trials when no noise was played," noted Pattwell in the statement.
On the other hand, children and adults quickly learned that the pattern did not have a noise and thus had less fear regarding the images.
Another study with mice was conducted in the project. A group of adolescent mice who were 29 days old did not have a lessening in fear to a particular stimuli, but younger and older mice were able to lose their fear gradually. However, the adolescent mice were never able to shake their fear. The researchers monitored the brains of the mice in an experiment and discovered that the part of the brain that processes emotion, the prefrontal cortex, is active when processing fear. On the other hand, the infralimbic prefrontal cortex works on reducing the fear association.
"In young and old mice, we see plasticity, which is activity in the infralimbic cortex, which helps the animals decrease their fear response when a threat no longer applies," remarked Pattwell in the statement. "Interestingly, we didn't witness similar activity in adolescent mice."
The scientists hope to pursue more studies to better understand fear response and it´s decoding in children as well as work on treatments that can be developed to assist adolescents.
"We need to investigate personalized approaches to treatment of these fear and anxiety disorders in teens," concluded Lee in the statement. "It is essential that we find a way to help teenagers become more resilient to the fear they experience during adolescence to prevent it from leading to a lifetime of anxiety and depression."