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PTSD is a mental health condition that can cause a wide range of debilitating symptoms, such as flashbacks to a traumatic event, being in a constant state of stress and avoiding certain situation and people, according to background information from the study.
Researchers identified a specific opioid receptor in the brain linked to emotion that is also associated with a specific group of PTSD symptoms, including listlessness and emotional detachment. They suggested their findings could help doctors develop targeted, or personalized treatments for the condition.
"Our study points toward a more personalized treatment approach for people with a specific symptom profile that's been linked to a particular neurobiological abnormality," explained the study's lead author, Dr. Alexander Neumeister, co-director of NYU Langone Medical Center's Steven and Alexandra Cohen Veterans Center for the Study of Post-Traumatic Stress Disorder and Traumatic Brain Injury, in an NYU news release. "Understanding more about where and how symptoms of PTSD manifest in the brain is a critical part of research efforts to develop more effective medications and treatment modalities."
The study, published online Sept. 17 in JAMA Psychiatry, represents a shift within the field of psychiatry away from a "one-size-fits-all" approach to more individualized treatments for mental health issues that target specific areas of the brain.
"People with cancer have a variety of different treatment options available based on the type of cancer that they have," noted Neumeister. "We aim to do the same thing in psychiatry. We're deconstructing PTSD symptoms, linking them to different brain dysfunction, and then developing treatments that target those symptoms. It's really a revolutionary step forward that has been supported by the National Institute of Mental Health (NIMH) over the past few years in their Research Domain Criteria Project."
"We know from previous clinical trials that antidepressants, for example, do not work well for dysphoria and the numbing symptoms often found in PTSD," Neumeister added. "Currently available antidepressants are just not linked specifically enough to the neurobiological basis of these symptoms in PTSD. Going forward, our study will help pave the way toward development of better options."
For the study, which was supported by the National Institute of Mental Health, the researchers compared brain scans of healthy people with scans of those diagnosed with PTSD, major depression, or generalized anxiety disorder, whose symptoms ranged from emotional detachment to isolation.
The participants were given a harmless radioactive tracer that illuminates a class of opioid receptors, known as kappa, when exposed to a PET scan (high-resolution positron emission tomography). Kappa opioid receptors bind to a natural opioid, known as dynorphin, which is released by the body during stressful times to reduce the feeling of dysphoria, marked by hopelessness, detachment and emotional unease.
Under chronic stress, however, kappa opioid receptors retract inside cells and do not bind to dynorphin, which can cause feelings of dysphoria.
The researchers found that fewer available kappa opioid receptors in the brain, however, were not linked to feelings of anxious arousal. They also saw a link between reduced cortisol levels, a hormone, and unavailable kappa opioid receptors. They concluded cortisol is an indicator for certain types of PTSD symptoms.
"This is the first brain-imaging study to explore any psychiatric condition using a protein that binds to the kappa opioid receptor system," Neumeister pointed out. "Returning veterans are a particularly vulnerable population, so we are hopeful this research will lead to better treatments for them, since they represent an escalating demographic of victims of PTSD."
-- Mary Elizabeth Dallas
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