Learning to overcome fear is difficult for teens, brain study finds

A new study by Weill Cornell Medical College researchers shows that adolescents' reactions to threat remain high even when the danger is no longer present. According to researchers, once a teenager's brain is triggered by a threat, the ability to suppress an emotional response to the threat is diminished which may explain the peak in anxiety and stress-related disorders during this developmental period.

The study, published Sept. 17 in the early online edition of the (PNAS), is the first to decode fear acquisition and fear "extinction learning," down to the synaptic level in the brains of mice, which mirror human . Also, through human and rodent experiments, the study finds that acquired fear can be difficult to extinguish in some adolescents. By contrast, the study shows that adults and children do not have the same trouble learning when a threat is no longer present.

"This is the first study to show, in an experiment, that adolescent humans have diminished fear extinction learning," says the study's lead author, Dr. Siobhan S. Pattwell, a at the Sackler Institute for Developmental Psychobiology at Weill Cornell. "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."

The study findings suggest there is altered plasticity in the of the brain during adolescence, with its inability to overcome fear, says the study's senior co-investigator, Dr. Francis Lee, professor of pharmacology and psychiatry at Weill Cornell Medical College, and an attending psychiatrist at NewYork-Presbyterian Hospital/Weill Cornell Medical Center.

"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," says Dr. Lee. "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."

Adolescent Mice Never Lose Their Fear Response

Fear learning is a highly-adaptive, evolutionarily conserved process that allows one to respond appropriately to cues associated with danger. In the case of psychiatric disorders, however, fear may persist long after a threat has passed, and this unremitting and often debilitating form of fear is a core component of many anxiety disorders, including post-traumatic stress disorders (PTSD).

Existing treatments, such as exposure therapy, are designed to expose an individual slowly to the cues associated with a perceived threat. This technique is used for a variety of fears, from wartime PTSD to fear of flying, as well as serious adolescent anxiety about school, says Dr. Lee, who treats, among others, patients with PTSD acquired during the World Trade Center collapse on September 11, 2001.

Anxiety disorders are increasingly being diagnosed in children and adolescents, but the success rate of -based exposure therapies are currently not known in this population. This study aimed to discover if they could be effective—and why or why not.

The human experiment was conducted at the Sackler Institute for Developmental Psychobiology at Weill Cornell in collaboration with its director, Dr. B.J. Casey, a study senior co-investigator, who is the Sackler Professor of and professor of psychology in psychiatry at Weill Cornell. In the experiment, a group of volunteers—children, adolescents and adults —wore headphones and skin sweat meters and were asked to look at a computer screen with a sequence of blue or yellow square images. One of the squares was paired with a really unpleasant sound. For example, 50 percent of the time the blue square would set off the noise.

If the participants acquired a fear of the noise, they showed increased sweat when viewing the image that was paired with it, says Dr. Pattwell. The same group was brought back the next day, and again viewed a sequence of blue or yellow squares, but this time there was no associated noise. "But teenagers didn't decrease their , and maintained their fear throughout subsequent trials when no noise was played," she says. However, the researchers documented that, unlike the teens participating in this study aged 12-17, both children and adults quickly learned that neither square was linked to a noxious sound, and this understanding rapidly decreased their fear response.

The mouse experiment, which used standard fear conditioning common in these types of animal studies, obtained similar findings. Adolescent mice (29 days old) did not decrease their fear response to stimuli that no longer existed, but younger and older mice did. Interestingly, the adolescent mice never lost their fear response as they aged.

The research team then monitored the brains of mice as they participated in the experiment. With the assistance of study senior co-investigator, Dr. Ipe Ninan, an electrophysiologist at NYU Langone Medical Center who is an assistant professor of psychiatry, the research team found that the prelimbic region in the prefrontal cortex, the brain region that processes emotion, is activated during acquisition of fear, and the infralimbic prefrontal cortex is used to extinguish this fear association. While other groups have suggested that the prefrontal cortex plays a role in extinction, no one has shown that this activity is at the level of the synapse—the connections between the neurons.

"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," says Dr. Pattwell. "Interestingly, we didn't witness similar activity in adolescent mice."

According to researchers there is much more to explore about the fear response and its decoding in human adolescents, such as whether genes contribute to susceptibility to altered fear learning, and most importantly, what can be done to help the adolescent population overcome fear.

"We need to investigate personalized approaches to treatment of these fear and in teens," says Dr. Lee. "It is essential that we find a way to help teenagers become more resilient to the they experience during adolescence to prevent it from leading to a lifetime of anxiety and depression."

Related Stories

Brain changes explain why teens have no fear

Jan 10, 2011

The brain undergoes changes in adolescence that suppress fearful experiences learned in childhood, said a study released Monday that could explain why teenagers act so brashly at times.

Animal behavioral studies can mimic human behavior

Jan 14, 2010

Studying animals in behavioral experiments has been a cornerstone of psychological research, but whether the observations are relevant for human behavior has been unclear. Weill Cornell Medical College researchers have identified ...

Recommended for you

Intervention program helps prevent high-school dropouts

Oct 24, 2014

New research findings from a team of prevention scientists at Arizona State University demonstrates that a family-focused intervention program for middle-school Mexican American children leads to fewer drop-out rates and ...

Bilingualism over the lifespan

Oct 24, 2014

It's a scene that plays out every day in Montreal. On the bus, in schools, in the office and at home, conversations weave seamlessly back and forth between French and English, or one of the many other languages represented ...

User comments

Adjust slider to filter visible comments by rank

Display comments: newest first

baudrunner
1 / 5 (2) Sep 27, 2012
Anxiety disorders are increasingly being diagnosed in children and adolescents
Junk food must have something to do with that. Today's kids do not stress their muscles enough to keep them fit and their intake of deep-fried and fried fast foods in general only increases strain on the already too-weak heart. Often, having irrational feelings of fear is symptomatic of a heart affliction.
HealingMindN
1 / 5 (1) Sep 27, 2012
@baudrunner, I know what you mean. Clinical studies by Derrick Lonsdale M.D. point out the effects of empty calories or malnutrition on adolescents which causes higher brain functions to revert back to the primitive limbic system. Therefore, we can only hope the aforementioned study took their subjects' diets in account (as if it made a difference to them.)

As far as this study at the Sackler Institute, I get the sneaking "pavlov's dogs" feeling that any paired stimuli would get a highly impressionable secondary reaction from a young mind.

Are we supposed to assume that a physical pain response equates to emotional fear? Is this what mainstream psychology is teaching? If that "really unpleasant sound" was obama on the state of affairs, I guess that can be fearful.
Mike_Massen
1 / 5 (2) Sep 28, 2012
Few things guys:-
Fructose depletes many useful minerals leading to mental retardation, article was also here on the medicalxpress web site...

Most people on western diets are deficient in many minerals, especially Zinc, Copper and Manganese.

Also fear is often tied up with other issues in respect of self-esteem, confidence and stubbornness and may result in types of behaviour such as here:-

http://en.wikiped...disorder

Roj
3 / 5 (1) Sep 29, 2012
Adolescent's suppress emotional response to threats by smoking pot.
Mike_Massen
1 / 5 (2) Sep 29, 2012
Roj exclaimed
Adolescent's suppress emotional response to threats by smoking pot.
They might in your town, they dont in mine.

If you and associates do observe that problem then:-
Focus should be on health first, communication second and in an environment which is beneficial, so if there is any pot or other addictive drugs or behaviours, Obviously take them away from that environment or they will become psychologically addicted whilst they are vulnerable on that path and that can lead to physiological addition too.

The task of any mature parent is to control influences and manage them when the child/adolescent is vulnerable and educate them to that potential. This seems to be necessary on many occasions even into adulthood as some young adults are still vulnerable when looked after by clueless parents for any length of time...

Sinister1811
1 / 5 (3) Sep 30, 2012
Being a long time sufferer of Social Anxiety, I believe that diet has little [if anything] to do with anxiety disorders. You could change your diet, and still feel awkwardly uncomfortable in public. There is little correlation, whatsoever, between diet and anxiety. If anything, a lot of anxiety disorders are a product of bad experiences in life. And gradually facing your fears is the only way to overcome it. But, unfortunately, it's always easy to relapse, and the symptoms can worsen.
Mike_Massen
2.3 / 5 (3) Sep 30, 2012
Sinister1811 lamented
..I believe that diet has little to do with anxiety disorders. You could change your diet, & still feel awkwardly uncomfortable in public. There is little correlation, whatsoever, between diet & anxiety. If anything, a lot of anxiety disorders are a product of bad experiences in life. & gradually facing your fears is the only way to overcome it...
I sympathise but, is based on mistaken assumption.

ie. that any diet is optimum in terms of the key leverage factors that allow us to think clearly & approach our understanding of where emotion fights intellect on a sec by sec basis to allow real change.

Most on western diets are seriously deficient in Copper & have insufficient others such as magnesium & omega-3.

Earnest advice is dramatically raise your mineral intake etc
http://en.wikiped...n_health

In conjunction with above, please look at Mg, Li, Omega-3 & WIDE differences in type food as mood moderators & add some self-hypnosis too...

G/L
Sinister1811
1 / 5 (3) Sep 30, 2012
That is very interesting. Thank you, Mike Massen! I appreciate the kind (and helpful) advice. And I will definitely take what you said under consideration.
Thanks again.