A drug that's currently used to treat Parkinson's disease could help people with phobias and Post-Traumatic Stress Disorder (PTSD), say researchers at the Translational Neurosciences (FTN) Research Center at Johannes Gutenberg University Mainz (JGU) and the University of Innsbruck. The team of researchers at the FTN is using both mice and human subjects to explore the effects of psychotherapy and the drug, L-dopa, on negative memories.

The relationship between Parkinson's disease and anxiety disorders is strong. According to a study published in the Postgraduate Medical Journal, 40% of patients with Parkinson's experience clinical anxiety. This is because the neutral pathways that control Parkinson's disease also affect anxiety. It's no surprise, then, that the medications that help patients with Parkinson's also have the potential to help people with PTSD and phobias.

The Clinical Trial

The experiment researchers are conducting uses a psychotherapy called fear extinction. It involves a patient being exposed to a neutral stimulus (like a circle appearing on a screen) alongside a painful stimulus. After a while, the person associates the circle with pain, a process called conditioning. To extinguish this fear, the patient is shown the neutral stimulus again without the painful stimulus, so the two things can be disassociated. For someone with arachnophobia, this would mean showing him or her pictures of a spider, video of a spider, or an actual spider so that he or she recognizes that the animal should not cause fear.

Fear extinction therapy has been proven successful for phobias and PTSD. However, some fears can returned in stressful situations, especially in patients with PTSD. According to researcher Raffael Kalisch, that's where L-dopa comes in. Kalisch has found that L-dopa is effective in preventing relapse in patients with PTSD or phobias. Patients who receive L-dopa after fear extinction are more likely to form a positive memory of the extinction, which will help replace the negative memory of the fear. "We would like to be able to enhance the long-term effects of psychotherapy by combining it with L-dopa," Kalisch said of his research.

The resulting clinical study is utilizing patients with arachnophobia to determine if L-dopa has an effect on therapy outcome.

Why Fear Extinction is Important

According to the US Department of Veterans Affairs, PTSD occurs in about 11-20% of veterans in the Iraq or Afghanistan wars, in about 30% of Vietnam veterans, and 10% of Gulf War veterans. PTSD is slightly less common in the entire population, with about 7-8% of people experiencing PTSD at some point in their lives. In any given year, 4-5% of the US population has a clinically significant phobia, according to PsychCentral. Needless to say, PTSD and phobias are a large problem in today's society.

If researchers at JGU and the University of Innsbruck are able to improve the effectiveness of fear extinction psychotherapy, it could mean a large improvement in the relapse rate of patients with these disorders. Such a breakthrough could cause markedly lower rates of PTSD and phobias in society, improving the way we treat patients with anxiety as a whole.

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"L-dopa medication could be helpful in treatment of phobias, post-traumatic stress disorder." Science Daily. http://www.sciencedaily.com/releases/2014/07/140709135925.htm. (Accessed July 11, 2014).

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