Unlike the related condition called post-traumatic stress disorder (PTSD), acute stress disorder does not appear to damage the brain\u2019s structure, according to new findings from a team of Hungarian and Israeli researchers. Acute stress disorder (ASD) is a diagnosable mental health condition that appears within the first 30 days of exposure to a highly traumatic event or situation capable of overwhelming the body\u2019s natural stress regulation mechanisms. In a study published in March 2015 in the journal Psychiatry Research: Neuroimaging, researchers from four Hungarian institutions and one Israeli institution sought to determine if people affected by ASD experience the same changes in brain structure that characterize PTSD. These researchers found no evidence of such structural change. Acute Stress Disorder Many people are aware of the existence of post-traumatic stress disorder, a diagnosable mental health problem that occurs when a person exposed to highly dangerous or possibly life-threatening circumstances develops a range of dysfunctional, disrupting symptoms as a consequence of his or her experience. However, most people probably don\u2019t know that, under current guidelines issued by the American Psychiatric Association, doctors only diagnose PTSD one month or more after exposure to the source of emotional trauma. If a damaging trauma reaction occurs before the designated timeframe for a PTSD diagnosis, doctors consider such a reaction to be an indication of acute stress disorder. Like a person with PTSD, a person with ASD commonly has symptoms that include unwanted reliving of an emotionally traumatic experience, a hypervigilant mental state associated with an overactive \u201cfight-or-flight\u201d response, a strong urge to avoid reminders of an emotionally traumatic experience and a notable uptick in \u201cdown,\u201d depressed or negative moods. In addition, a person with acute stress disorder must experience symptoms of dissociation, a dysfunctional state characterized by such things as a detachment from reality, amnesia and a reduced ability to interact with others. Most people who receive an ASD diagnosis eventually meet the criteria for a PTSD diagnosis, the U.S. Department of Veterans Affairs\u2019 National Center for PTSD reports. However, some people with ASD never develop PTSD; conversely, some people later diagnosed with PTSD never meet the criteria for an ASD diagnosis in the month following their trauma exposure. PTSD\u2019s Effect on the Brain Untreated PTSD can substantially alter the brain\u2019s normal healthy function, as well as its basic structure. Functional changes associated with the condition include altered production of the body\u2019s chief stress hormones, increased stress sensitivity and a reduced ability to make, store or recall memories. Structural changes associated with PTSD include harmful modification of the nerve pathways in a part of the brain called the hippocampus, which has responsibility for normal memory function and the ability to use spatial information. They also include harmful modification of the nerve pathways in a part of the brain called the amygdala, which plays a crucial role in the ability to process strong emotions and maintain a sense of psychological well-being. ASD\u2019s Effect on Brain Structure In the study published in Psychiatry Research: Neuroimaging, researchers from Israel\u2019s University of Haifa and Hungary\u2019s Nyiro Gyula Hospital, Bacs-Kiskun County Hospital, University of Szeged and Budapest University of Technology and Economics used a scanning technology called magnetic resonance imaging (MRI) to help identify any possible changes in the brain structure of people affected by acute stress disorder. Included in the study were 75 people with a history of trauma exposure who developed ASD, 60 people with a history of trauma exposure who did not develop ASD and a comparison group of 60 people who had no history of trauma exposure. After analyzing the results of the MRI exams, the researchers concluded that people with acute stress disorder do not have altered brain structure in the hippocampus or the amygdala when compared to their trauma-exposed counterparts who don\u2019t develop ASD. The researchers also concluded that the hippocampus and the amygdala in people affected by ASD don\u2019t differ in any structurally significant way from the hippocampus and amygdala found in the brains of people who don\u2019t have a history of exposure to serious emotional trauma. The study\u2019s authors also found that the presence of ASD does not appear to alter the size of the hippocampus or amygdala. Based on the totality of their findings, they concluded that acute stress disorder is probably not linked to the same types of damaging changes in brain structure that occur in people with PTSD.