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PTSD: A Biological Response Gone Awry? Many people have been traumatized by the September 11th terrorist attacks. Unfortunately, as a result of these events, some individuals will become diagnosed with posttraumatic stress disorder (PTSD) and may also develop concurrent depression, anxiety disorders, and substance abuse. The challenge is to identify individuals vulnerable to PTSD and for them to receive treatment promptly before neuronal imprinting occurs. Below, we provide the latest research findings on what may cause a biological response to stress to go awry and the newest treatments available. The very same autonomic fight or flight responses that can save individuals in a life-threatening situation can ruin lives if these responses become hyper-regulated as a result of trauma. While emotional dissociation, for instance, can be an adaptive response to situations of unimaginable horror, it can leave a person emotionally frozen, unable to maintain normal relationships with others. Adrenaline is likewise a key ally in danger, but can leave a person pathologically fearful if it continues to flood the body after the danger is gone. Ironically, systems that are protective to the individual in extreme situations can become pathological in the long run. WHO'S AT RISK? PTSD is a serious and debilitating medical condition that affects not only war veterans and disaster victims but also as many as 1 in 12 adults in the general population at some time in their lives. Of those individuals exposed to traumatic events, approximately 15% to 24% will develop PTSD. Women are twice as likely to develop PTSD compared to men despite women having a lower prevalence of exposure to trauma.1,2 In addition to female sex, factors associated with an increased risk for PTSD following trauma exposure include:
PTSD IN CHILDREN The recognition that PTSD occurs in children is a relatively new observation. As recently as the 1980s, it was widely believed that children have only transient reactions to single traumatic events and soon put the experience behind them. This misunderstanding largely resulted from researchers failing to interview the children themselves about their experiences, and instead relying on reports from parents and teachers. If asked, children aged 6 years or younger often provide graphic accounts of their experiences and allude to the event in repetitive drawings and play. The most troubling symptoms are recurring, intrusive thoughts about the event. Sleep disturbances, fear of the dark, and nightmares are common, particularly during the first few weeks. The ensuing tiredness may at least in part explain the difficulties in concentration that many children report following trauma, although problems with memory are also observed. Separation difficulties are also widespread, even among teenagers, and it is not un-usual for children not to want to let their parents out of their sight for the first few days following the traumatic event. SYMPTOMS PTSD is classified as an anxiety disorder and is typically defined by the coexistence of 3 clusters of symptoms: 1. Re-experiencing: An overwhelming sense of reliving the traumatic event, with feelings of fear and panic, and with corresponding physiologic responses such as heart pounding. 2. Avoidance: Both of activities or places associated with the traumatic event and unrelated situations and events. 3. Hyperarousal: Manifested as insomnia, anger, and difficulty in concentrating, hypervigilance, and an exaggerated startle response. One of the most disabling features of PTSD is when patients withdraw from social contacts and show very little range of emotional response. These so-called "numbing symptoms" are usually the most distressing to family members because patients with PTSD will often not have normal emotional responses to family events, such as a death in the family. Nightmares are a hallmark feature of PTSD. Their existence is nearly diagnostic of the disorder because nightmares are not associated with most of the other major psychiatric illnesses. Thomas C. Neylan, M.D., at the University of California-San Francisco, (a 1994 NARSAD Young Investigator) has examined the biology of sleep and arousal disturbances in patients with PTSD and has found that nightmares are very strongly associated with the extent and severity of the exposure. Of increasing interest are the cognitive disturbances associated with PTSD. Individuals often have an increased attention bias towards threat- or trauma-related stimuli. But even in the absence of threat stimuli, PTSD patients tend to have impairments in recall and other memory measures. A BIOLOGICAL RESPONSE GONE AWRY? Traumatic events in themselves, no matter how severe, may not cause PTSD. Some individuals manage to emerge psychologically intact after even brutal and prolonged trauma. Little is known at present why some people continue to experience chronic PTSD, while the majority does recover. Some researchers believe that the development of PTSD may be assisted by an atypical biological response to trauma, which may in turn, lead to a poorly adaptive psychological state. This atypical response might result from the presence of pre-traumatic vulnerability factors. By studying the stress-resilient, as well as those victimized by trauma, researchers hope that current research will yield vastly improved therapeutic progress. DSM-IV Criteria for Diagnosis of PTSD HYPER-REGULATED STRESS HORMONES Chronic PTSD is associated with a distinct set of biological changes, primarily involving the hypothalamic-pituitary-adrenal (HPA) axis. This axis plays a major role in an individual's response to stress. Following exposure to a stressor, a cascade of biochemical activity is initiated, known as the basic HPA axis stress-response cascade. The levels of both catecholamines and cortisol hormones increase during this response, relative to the severity of the stressor. In addition, the actions of these two systems appear to be synergistic. Whereas catecholamines facilitate the availability of energy to vital organs, cortisol functions as an "anti-stress" hormone, helping to contain or shut down the neural defensive reactions that have been initiated by stress. Studies in victims of motor vehicle accidents and rapes have shown that those who went on to develop PTSD, as a group, had lower blood cortisol levels at the time of admission to the emergency room compared with subjects who did not develop a psychiatric disorder or those who went on to develop depression.3,4 Studies have also shown that trauma survivors who go on to develop PTSD have increased heart rates compared with those who do not develop the condition. Some researchers believe that low cortisol is not the salient feature of the neuroendocrinology of PTSD. Rather, low cortisol is a downstream effect of a more basic change--an enhanced negative feedback inhibition resulting from increased glucocorticoid receptor sensitivity. Glucocorti-coids are stress hormones released by the HPA axis. In contrast to the decreased number of glucocorticoid re-ceptors typically observed in major depression and in stress, the situation appears to be reversed in PTSD. Sev-eral studies have demonstrated that lymphocyte glucocorticoid receptors are higher in PTSD patients than in nontraumatized subjects without psychiatric disorders. Glu-cocorticoid receptors also appear to be more sensitive in PTSD patients as demonstrated by administration of the steroid, dexamethasone (a synthetic steroid that mimics the effects of cortisol). Rachel Yehuda, Ph.D. of Mount Sinai School of Medicine has shown that treatment with dexamethasone produced a significant decrease or down-regulation of the lymphocyte glucocorticoid receptor number in combat veterans with PTSD but not in trauma survivors without PTSD or normal controls. This finding suggests that the glucocorticoid receptors of PTSD subjects show a greater response to the administration of the synthetic steroid.5 America's Inner Cities Youth at High Risk for PTSD CHANGES IN BRAIN? An expert on posttraumatic stress disorder, Dennis Charney, M.D. (a NARSAD Scientific Council Member), and his group at the National Institute of Mental Health have found important evidence that trauma may literally change the brain. Specifically, Dr. Charney's group has found that PTSD sufferers tend to show reduced hippocampus size. Other studies examining cerebral activity in relation to traumatic stimuli have found the amygdala and anterior cingulate (brain structures involved in generating negative emotions and also in forming emotional memories) to be highly activated. Thus, traumatic reminders appear to cause excessive activation of brain areas linked with emotional regulation in PTSD patients. In addition, the medial prefrontal cortex (brain region in-volved in the recall of emotional experiences and the processing of emotional responses) was found to show enhanced activity. This area of the brain is modulated by norepinephrine, a key neurotransmitter in the generation of a coordinated stress response. PSYCHOLOGICAL TREATMENT Treatment of PTSD can be divided into psychological and biological (pharmacological) approaches. Psychological treatment includes behavioral, cognitive, and psychodynamic treatments. Many researchers believe that direct exposure therapies within a cognitive-behavioral framework may offer the most benefit. Cognitive-behavioral therapies aim to help patients make sense of their experiences and to master their feelings of anxiety and helplessness. The majority of PTSD treatment packages include anxiety management techniques such as relaxation training, stress inoculation therapy, cognitive restructuring, and breathing retraining. The key element, however, remains the confrontation of the traumatic event by the patient through techniques such as systematic desensitization, flooding, prolonged exposure, and implosive therapy. Having patients gain a better understanding of their disorder and learn the neurobiology of fear often helps them to understand that fear is associated with biological changes and that PTSD may be a failure to shut them off properly. IMAGERY-REHEARSAL THERAPY A form of psychotherapy in which individuals experiencing intense nightmares are asked to revisit their sleep disturbances is known as imagery-rehearsal therapy. Re-cent studies have found this therapy to be an effective means of decreasing the severity of symptoms in PTSD. In imagery-rehearsal therapy, individuals change the scenario of a recent nightmare anyway they wish, writing down the improved version, and then mentally rehearsing it in a relaxed state. John Lauriello, M.D., (a 1995 NARSAD Young Investigator) of New Mexico School of Medicine found not only had imagery-rehearsal therapy reduced the number of nightmares patients were having, but that it also helped to reduce some of their PTSD symptoms--such as, intrusive thoughts or emotional arousal. EYE MOVEMENT DESENSITIZATION Another new therapy that has shown some initial promise is eye movement desensitization, whereby patients are asked to recall the traumatic event in images while systematically moving their eyes rapidly. Although no studies have been done in children or adolescents, William Yule, Ph.D. of the University of London Institute of Psychiatry has found the technique to be especially beneficial in children traumatized by road traffic accidents. It is not clear if the eye movement is necessary or whether it serves merely as a helpful distraction for patients while they expose themselves to the trauma memories and, thereby adjust to them. MEDICATIONS During the last 10 years, several studies have shown medications to be effective in treating PTSD. Specifically, antidepressants can improve symptoms of intrusion and avoidance as well as depression, insomnia, and anxiety. Re-cently, selective serotonin reuptake inhibitors (SSRIs) have been shown to significantly reduce PTSD symptoms in various individuals, and the study of these and other antidepressants is very promising. Currently, sertraline (Zoloft) and Paroxetine (Paxil) are the only two SSRIs approved for treatment of PTSD. Mixed results have been obtained from the use of benzodiazepines, with severe withdrawal symptoms being reported in some patients. Agents that act to stabilize mood--including lithium, valproate (Depakote), and carbamaze-pine (Tegretol)--have also been studied and have been shown to reduce irritability and improve impulse control. Another anticonvulsant drug, topiramate (Topamax), has recently shown promise in the treatment of PTSD. Potential Stage-Based Treatment for PTSD Some researchers believe that beta-blockers (like propanolol) commonly used to treat hypertension could potentially block the encoding of trauma. Under acute stress, an individual gets increas-es in norepinephrine, which is involved in the programming of the traumatic memory. If a person received treatment with a beta-blocker as soon as possible after a trauma, the individual's memory of the trauma possibly might not be preset so strongly. References 1. Breslau N, Davis GC, Andreski P, et al. Traumatic events and posttraumatic stress disorder in an urban population of young adults. Arch Gen Psychiatry 1991; 48:216-222. 2. Kessler RC, Sonnega A, Bromet E, et al. Posttraumatic stress disorder in the National Comorbidity Survey. Arch Gen Psychiatry 1995;52:1048-1060. 3. McFarlane AC, Atchison M, Yehuda R. The acute stress response following motor vehicle accidents and its relations to PTSD. Ann N Y Acad Sci 1997;821:437-441. 4. Resnick HS, Yehuda R, Pitman RK, et al. Effects of previous trauma on acute plasma cortisol level following rape. Am J Psychiatry 1995;152:1675-1677. 5. Yehuda R, Boisoneau D, Lowy MT, et al. Dose-response changes in plasma cortisol and lymphocyte glucocorticoid receptors following dexamethasone administration in combat veterans with and without PTSD. Arch Gen Psychiatry 1995;52:583-593.
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