Posts tagged phobias
Articles and news from the latest research reports.
L-dopa medication could be helpful in the treatment of phobias and post-traumatic stress disorder
A drug used to treat Parkinson’s disease could also help people with phobias or post-traumatic stress disorder (PTSD). Scientists of the Translational Neurosciences (FTN) Research Center at Johannes Gutenberg University Mainz (JGU) are currently exploring the effects of psychotherapy to extinguish fears in combination with L-dopa. This drug does not only help movement disorders, but might also be used to override negative memories.
Professor Raffael Kalisch, head of the Neuroimaging Center (NIC) of the JGU Translational Neurosciences Research Center, and his collaborators at the University of Innsbruck are conducting research in mice and in humans into the psychological and neurobiological mechanisms of anxiety and fear. “Fear reactions are essential to health and survival, but the memories of angst-inducing situations may cause long-term anxiety or phobias,” explained Kalisch. In psychotherapy, the ’fear extinction’ method is used in exposing people to a threat but without the adverse consequences. Latest research has proven that extinguishing fear also predicts mental health after trauma, suggesting extinction may be an important resilience mechanism.
Fear extinction involves a person being presented with a neutral stimulus, such as a circle on a screen, together with a painful sensation. Soon the person predicts pain in response to the circle on the screen and fear becomes conditioned. Then the person is shown the circle again, but this time without the painful stimulus, so that the person can disassociate the two factors. A person who is afraid of spiders, for example, will in psychotherapy be confronted with spiders in a way that reassures them that the spider is harmless.
In another research program, Belgian scientists tested the ability to extinguish fear in soldiers later deployed to a war zone and found differences in the soldiers’ resilience to traumatic memories. Some experienced post-traumatic stress symptoms following their deployment, whereas those who were able to extinguish fear in the laboratory maintained a good state of mental health. “If you are mentally flexible enough to change the associations that your mind has created, you might be better able to avoid lasting damage,” explained Kalisch. In cooperation with other scientists, Kalisch has found first evidence that this process of changing negative associations might involve the brain’s systems for reward and pleasure and depend on release of the neurotransmitter dopamine that helps control them.
However, even after successful extinction, old fear associations can return under other stressful circumstances. This might involve the development of PTSD or a relapse after successful psychotherapy. Kalisch has found that L-dopa, a drug to treat Parkinson’s disease, can prevent this effect and could therefore possibly be used to prevent relapse in treated PTSD or phobia patients. L-dopa is taken up by the brain and transformed into dopamine that not only controls the brain’s reward and pleasure centers and helps regulate movement, but also affects memory formation. The person receiving L-dopa after extinction will thus create a stronger secondary positive memory of the extinction experience and will thus be able to more easily replace the negative memory. This raises new questions about the role of primary fear memories and secondary prevention by L-dopa. “We would like to be able to enhance the long-term effects of psychotherapy by combining it with L-dopa,” said Professor Raffael Kalisch. To this end, he is about to start a clinical study of people with a spider phobia to determine the effects of L-dopa on therapy outcome. “Manipulating the dopamine system in the brain is a promising avenue to boost primary and secondary preventive strategies based on the extinction procedure,” he continued.
Publication:
Raczka, K. A. et al. (2011), Empirical support for an involvement of the mesostriatal dopamine system in human fear extinction, Translational Psychiatry 1:e12
Haaker, J. et al. (2013), Single dose of L-dopa makes extinction memories context-independent and prevents the return of fear, PNAS Plus - Biological Sciences - Psychological and Cognitive Sciences 110 (26): E2428-36
(Source: uni-mainz.de)
The anatomy of fear: Understanding the biological underpinnings of anxiety, phobias and PTSD
Fear in a mouse brain looks much the same as fear in a human brain.
When a frightening stimulus is encountered, the thalamus shoots a message to the amygdala — the primitive part of the brain — even before it informs the parts responsible for higher cognition. The amygdala then goes into its hard-wired fight-or-flight response, triggering a host of predictable symptoms, including racing heart, heavy breathing, startle response, and sweating.
The similarities of fear response in the brains of mice and men have allowed scientists to understand the neural circuitry and molecular processes of fear and fear behaviors perhaps better than any other response. That understanding has spurred breakthroughs in treatments for psychiatric disorders that are underpinned by fear.
Anxiety disorders are one of the most common mental illnesses in the country, with nearly one-third of Americans experiencing symptoms at least once during their lives. There are generalized anxiety disorders and fear-related disorders, which include panic disorders, phobias, and post-traumatic stress disorder (PTSD).
Emory psychiatrist and researcher Kerry Ressler is on the front lines of fear-disorder research. In his lab at Yerkes National Primate Research Center, he studies the molecular and cellular mechanisms of fear learning and extinction in mouse models. At Grady Memorial Hospital, he investigates the psychology, genetics, and biology of PTSD. And through the Grady Trauma Project, he works to draw attention to the problem of inner city intergenerational violence.
"If you look at Kerry’s work, it can seem like it’s all over the place — he’s got so many studies going on, and he collaborates with so many other scientists," says Barbara Rothbaum, associate vice chair of clinical research in psychiatry and director of the Trauma and Anxiety Recovery Program at Emory. "But they are all pieces to the same puzzle. All his work, from molecular to clinical to policy, fits together and starts telling a story." A Howard Hughes Medical Institute investigator, Ressler was recently elected to the Institute of Medicine — one of the highest honors in the fields of health and medicine. He was named a member of a new national PTSD consortium led by Draper Laboratory. And he recently appeared on the Charlie Rose show’s brain series.
Panic attacks seem to tie the fear-related disorders together, he explained on Charlie Rose. Everyone experiences fear, which evolved as a survival mechanism, but it only rises to a clinical level when people are unable to function normally in the face of it. For instance, PTSD includes not only intrusive thoughts, memories, nightmares, and startle responses, but also the concept of avoidance, which may extend to other areas of the individual’s life.
"There’s a patient I’ve seen who was attacked in a dark alley," Ressler shared on the show. "Initially it just felt dangerous to go out at night, but after a while she grew afraid of men and couldn’t go to that part of town. Then she couldn’t leave her house, and finally, her bedroom. The world got more and more dangerous."