María Dolores Braquehais(1) and Leo Sher(2)
1. Vall d’Hebron University Hospital, Barcelona, Spain
2. Columbia University and New York State Psychiatric Institute, New York, New York, USA
Immigration and Mental Health: Stress, Psychiatric Disorders and Suicidal Behavior Among Immigrants and Refugees. Hauppauge, New York: Nova Science Publishers, 2010, 350 pages.

Trauma is a widespread experience, inherent to nature, and has been experienced and expressed by humans in many different ways in space and time. The post-traumatic stress disorder (PTSD) consists of a cluster of signs and symptoms developed in response to an extreme traumatic stressor. The general population prevalence of PTSD is estimated to range between 2-15%, whereas the prevalence in risk groups is reported to vary from 3-58%. These variations may be due to several factors: the prevalence of trauma exposure, the magnitude and quality of the stressor/s, differences in individual vulnerability, discordances in psychosocial narratives, and their consideration of resilience and distress, and the methodology that is being used in each study. The response to trauma depends on pre-trauma, peri-trauma, and post-trauma variables. Trauma may lead to a persistent failure of the inhibitory processes ruled mainly by the frontal cortex over a fear-motivated hyperresponsive limbic system. From an evolutionary perspective, the main psychobiological circuits involved in emotions related to fear and anger are primitive, and they have their basis in ancient sub-cortical regions, whereas well-developed cortical regions, such as the prefrontal cortex, play a modulatory role. Abnormalities in the balance between inhibitory and excitatory neurocircuits could also be involved in the pathophysiology of PTSD. However, a comprehensive multi-level approach to trauma should not only focus on the basic psychobiological mechanisms but also on the specific psychosocial context within which the response to trauma developes.