<prompt> Post traumatic stress disorder is due to?Head injuryCVDMinor stressMajor life threatening events  <response>: Ans. is d i.e., Major life treatening events Stressors for stress disorders Stress disorders occur after an extreme traumatic events involving the threat of personal death or injury. They can arise from experiences in war, torture, natural catastroph earthquake, volcano, floods, assault, rape, and serious accidents e.g., in car in burning building. Symptoms of PTSD develop within 6 months of stressor, However 10 patients have delayed onset.Risk factors for Stress disorders1 Vulnerability factors: - Low education, Lower social class, female gender, low self esteemneurotic traits, previous traumatic events including childhood trauma, previous self or family history of psychiatric problems mood anxiety disorders.2 Protective factors: - High IQ, higher social class, male gender, psychopathic traits, chance to view body of dead relative friend.3 Biological factors: - Following systems are hyperactive in PTSD : -a Noradrenergic systemb Opioid systemc Hypothalamic-pituitary-adrenal HDA axis Recently, the role of Hippocampus in PTSD has received increased attention. Animal studies have shown that stress is associated with structural changes in the hippocampus, and studies of combat veterans with PTSD have revealed a lower average volume in the hippocampal region of the brain. Structural changes in the amygadala, an area of the brain associated with fear, have also been demonstrated. 