Causes of PTSD

Post-traumatic Stress Disorder Causes And Risk Factors

Post-traumatic stress disorder (PTSD) affects people who have either experienced or witnessed a traumatic or life-threatening event. There can be a number of different PTSD causes that can lead to the onset of this disorder.

Understanding PTSD

PTSD is an anxiety disorder related to trauma and stressors. It often develops after one has been exposed to a terrifying experience or severe trauma. Although mostly common in the military due to combat stress, the condition can equally affect civilian populations. In most civilians, post-traumatic stress disorder can develop due to exposure to various traumas like accidents, natural disasters, sexual abuse, childhood abuse or any other life-threatening experiences. According to recent research 1 , the lifetime prevalence of PTSD is around 7.3% among general people. The study found that the 12-month prevalence of PTSD in the U.S. adult population was around 3.6%. Moreover, women were more likely to be affected by PTSD than men.

Post-traumatic stress disorder is a treatable condition and the symptoms can be successfully managed. Once the PTSD causes have been identified, a mental health professional can devise an effective treatment plan to help the patient live a healthier life.

Common PTSD Causes

Although the exact cause of post traumatic stress disorder is not yet known, it is believed that a combination of different factors, such as genetic, psychological, social and physical factors, may contribute to the onset of this disorder. The condition affects stress hormones and chemicals which responds to stress and transfers information among nerves. The National Health Service (NHS), UK, explains “PTSD can develop immediately after someone experiences a disturbing event, or it can occur weeks, months or even years later.”

It is estimated that 1 in every 3 individuals experiencing a traumatic event may be affected by this form of anxiety disorder. However, it is yet to be determined why some people are affected by it while others are not. Post traumatic stress disorder is commonly observed among people who have a history of mental health issues or go through repeated stressors. Here are some of the most PTSD causes and factors that may influence the onset of this disorder:

1. Traumatic events

Exposure to a single or multiple traumatic events is a crucial aspect of this disorder. Research 2 shows that severity and nature of the trauma can determine the risk factors and severity of the condition. A 2016 study 3 reveals that the event must include exposure to threatened or actual death, injury or sexual violence. Moreover, exposure must involve directly experiencing or witnessing the traumatizing event. It may also involve learning about a traumatic experience of a family member or friend. PTSD can also be caused by extreme or constant exposure to unpleasant details about the event, such as the jobs of first responders, police officers or military photographers. Exposure to such trauma through electronic mediums has been excluded by the DSM-5 as one of the PTSD causes.

A 2018 scientific analysis 4 states “An identified psychological stressor is required to generate the classic symptomatic triad together with other psychopathological phenomena. There is also a neurobiological correlation of stress response to threat.”

2. Biological factors

A number of biological indicators have been recognized by experts which may be associated with the PTSD causes. A smaller hippocampal volume and exaggerated startle responses may be probable biomarkers for increased risk for onset. One 2003 study 5 states “MRI studies using the manual tracing method have shown a smaller-than-normal hippocampal volume in patients with posttraumatic stress disorder.” Another study shows that army personnel with higher volumes of glucocorticoid receptors in leukocytes were more likely to develop this condition after a traumatic event. Research 6 also indicates that the condition is often ascribed to –

  • Dysfunction of recovery systems
  • Failure to differentiate between safety and danger
  • Disturbed and distorted memory
  • Impaired fear regulation and extinction
  • Sensitized neurochemical responses


According to the researchers, “PTSD is accompanied by morphological changes of the hippocampus, amygdala, and cortical regions, possibly reflecting preexistent vulnerability factors, or consequences of the disorder.” Post traumatic stress disorder is related with a number of neurochemical processes which may change and vary as the anxiety disorder evolves over time. Microbiota variations and inflammatory immune alterations are also associated with condition. However, it is unclear whether these are a consequence of the disorder or etiologically related to the mental illness.

3. Hormones & brain structure

According to the NHS, UK, “Studies 7 have shown that people with PTSD have abnormal levels of stress hormones.” Through imaging techniques, researchers have assessed that our body reacts to traumatic experiences by releasing the stress hormone adrenaline. This enables the human body for the fight or flight response. “In the brain, adrenaline and the brain chemical norepinephrine stimulate the amygdala, a deep brain structure that spurs the formation of vivid, emotional memories of the threat,” explains Harvard Health Publishing. Although it is an excellent survival mechanism that puts us on high alert, for a person with PTSD it can be extreme and overwhelming. Environmental signs, coupled with our memories, can trigger fear responses that are exaggerated and distorted to non-threatening situations. This is one of the primary PTSD causes that can significantly disrupt the normal functioning of the sufferer.

Roger K. Pitman, M.D., professor of psychiatry at Harvard Medical School, believes that the amygdala tends to be “over-reactive” in people with this disorder. He says that researchers have “found that two areas of the brain which help keep the amygdala in check, the hippocampus and the anterior cingulate cortex, appear not to function as well in those with PTSD.” Imaging studies have revealed that in patients with this particular disorder, the hippocampus 8 & the anterior cingulate cortex appear to be smaller than usual. It was also found that these were smaller in female sufferers who experienced childhood physical and sexual abuse.

4. Genetics

Although the genetic influences in the development of post traumatic stress disorder are not yet clearly understood, experts believe that the condition may be hereditary. Research indicates that around 30% of the PTSD 9 variance is a result of genetics. A 2011 research 10 reveals “PTSD diagnosis was more frequent in adult children of Holocaust survivors with PTSD as compared to children of Holocaust survivors without PTSD. A similar finding has been reported in adult children of Cambodian refugees whose parents had PTSD.”

The research paper also reveals that studies on twins with identical genetic inheritance can enable the researchers to distinguish between genetic factors and environmental factors that may influence the onset. Twin studies show that genetics can impact the exposure to traumatic experiences. It is identified as gene-environment correlation and is associated with the influence of genetics on mood and behavior, like irritability, anger, temperament etc. One study 11 found that identical twins (monozygotic), with the disorder exposed to Vietnam war, were more likely to develop PTSD compared to non-identical twins (dizygotic). The researchers state “genetic factors account for 13% to 30% of the variance in liability for symptoms in the reexperiencing cluster, 30% to 34% for symptoms in the avoidance cluster, and 28% to 32% for symptoms in the arousal cluster.”

Post-traumatic stress disorder also shares several genetic influences that are commonly seen in different mental health conditions. Generalized anxiety disorder and panic disorder share around 60% genetic similarities with PTSD. Moreover, substance, alcohol and nicotine abuse share around 40% of the same genetic variance. Hence, genetics are considered as one of the primary PTSD causes.

5. Other factors

Apart from these, other psychiatric disorders may also heighten the risk of onset. The NHS, UK explains “If you have had depression or anxiety in the past, or you do not receive much support from family or friends, you’re more susceptible to developing PTSD after a traumatic event.” PTSD symptoms can also be triggered as an instinctive mechanism to enable a person to survive traumatic experiences. In this context, flashbacks may compel patients to think about the details of the event to enable them to face and prepare for another similar event in future. Hyperarousal may occur to ensure the patient reacts instantly to the next crisis. “But while these responses may be intended to help you survive, they’re actually very unhelpful in reality because you cannot process and move on from the traumatic experience,” adds the NHS, UK.

Risk Factors For PTSD

Apart from the PTSD causes mentioned above, there are several risk factors that determine why some individuals develop post traumatic stress disorder, while others don’t even after experiencing similar traumatic events. According to a Harvard Health article, “Individual traits and circumstances help determine how an event is perceived and how emotionally overwhelming it is.” Moreover, the type of trauma and the specific reaction of the patient are also considered by mental health professionals. Moreover, the circumstances and point in life of the patient when the traumatic event occurs may also be a predicting factor.

The U.S. National Library of Medicine 12 outlines the following risk factors that may lead to the development of the disorder:

  • History of mental illness
  • Gender of a person
  • Traumatic experiences in childhood
  • Intense fear or helplessness
  • Physical harm or injury
  • Witnessing a murder or a corpse
  • Lack of social support after traumatic events
  • Low socio‐demographic background
  • Coping with additional stress after the trauma, such as injury or loss of a loved one
  • Substance use


Risk may increase due to temperamental factors like externalizing behaviors and anxiety-related problems. Other probable risk factors may include –

  • Combat-related trauma
  • Adverse childhood experiences
  • Sexual assault
  • Family dynamics
  • Less education
  • Interpersonal conflicts
  • Near-death experience


Apart from these and the common PTSD causes, cultural factors also play a determining role. The condition can worsen due to repeated exposure to violence, dysfunctional family, financial stress, lack of social support and ineffective coping mechanisms, like alcohol or drug use. According to the United States Department of Veterans Affairs, PTSD often results from “innate biological and physiological mechanisms. It is not the result of moral failing or weakness in character.” The disorder can be triggered by various factors, such as –

  • Argument
  • Media stories
  • Loud noises
  • Life stressors
  • Anniversaries/holidays
  • Insensitive questions traumatic experiences


A 2007 research paper 13 on post traumatic stress disorder by Jonathan Bisson, a professor in psychiatry at Cardiff University School of Medicine, states “Anyone can develop the disorder after a traumatic event, but the incidence increases with the severity of the trauma.” Here are some additional risk factors presented by researcher Jonathan Bisson:

1. Pretraumatic factors

  • Prior trauma
  • Prior psychiatric disorder
  • Being a woman
  • Personality and locus of control
  • Race or minority status
  • Lower socioeconomic status
  • Lack of education
  • Family history of mental conditions

2. Peritraumatic factors

  • Peritraumatic dissociation
  • Peritraumatic emotions
  • Intensity of trauma
  • Perceived injury or threat to life

3. Post-traumatic factors

  • Lack of social support
  • Subsequent or additional life stress


According to a meta-analysis of risk factors 14 for posttraumatic stress disorder, “factors operating during or after the trauma, such as trauma severity, lack of social support, and additional life stress, had somewhat stronger effects than pretrauma factors.”

Treatment Can Help

We can identify the precise PTSD causes with the help of a mental health professional or a healthcare expert and seek necessary medical attention. With the help of therapy and medication, PTSD symptoms can be managed effectively and the patient can live a normal, healthier life. However, as each of us are different, our experiences will be different as well. Hence, PTSD causes may vary from one person to the other. This is why it crucial to seek medical help, devise a sustainable treatment plan and follow the doctor’s instructions for full recovery.

References:
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  6. https://www.amazon.com/Immune-System-Mental-Health/dp/0128113510?dchild=1&keywords=The+Immune+System+and+Mental+Health&qid=1613113770&sr=8-1&linkCode=ll1&tag=mindhelp-20&linkId=6f8d25df847b86fc25fbe584838186de&language=en_US&ref_=as_li_ss_tl []
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  8. Logue, M. W., van Rooij, S., Dennis, E. L., Davis, S. L., Hayes, J. P., Stevens, J. S., Densmore, M., Haswell, C. C., Ipser, J., Koch, S., Korgaonkar, M., Lebois, L., Peverill, M., Baker, J. T., Boedhoe, P., Frijling, J. L., Gruber, S. A., Harpaz-Rotem, I., Jahanshad, N., Koopowitz, S., … Morey, R. A. (2018). Smaller Hippocampal Volume in Posttraumatic Stress Disorder: A Multisite ENIGMA-PGC Study: Subcortical Volumetry Results From Posttraumatic Stress Disorder Consortia. Biological psychiatry, 83(3), 244–253. https://doi.org/10.1016/j.biopsych.2017.09.006 []
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