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What is PTSD?

What is Post Traumatic Stress Disorder?

    The Diagnostic and Statistical Manual of Mental Disorders Fifth Edition or (DSM-5) states that PTSD is caused by ‘Exposure to actual or threatened death, serious injury, or sexual violence …’.  The DSM-5 then describes in great detail how a person can be exposed to these traumatic circumstances along with symptoms and behaviours that commonly occur with such an exposure.  These exposures described in the DSM-5 include:

  • Directly experiencing the traumatic event.

  • Witnessing, in person, the event(s) as it occurred to others.

  • Learning that the traumatic event(s) occurred to a close family member or close friend. In cases of actual or threatened death of a family member or friend, the event(s) must have been violent or accidental.

  • Experiencing repeated or extreme exposure to aversive details of the traumatic event(s) (ie: first responders collecting human remains, police officers repeatedly exposed to details of child abuse).

    Post-traumatic stress disorder (PTSD) is a mental illness. A mental illness that we at OSI-CAN prefer to think of as an Operational Stress Injury or Occupational Stress Injury that one can recover from rather than to refer to it as a Disorder.  PTSD or an OSI involves exposure to trauma involving death or the threat of death, serious injury, or sexual violence.

    Some jobs or occupations put people in dangerous and traumatic situations. Military personnel, first responders (police, firefighters, and paramedics), doctors, and nurses experience higher rates of PTSD than other professions.

    Something is traumatic when it is very frightening, overwhelming and causes a lot of distress. Trauma is often unexpected, and many people say that they felt powerless to stop or change the event. Traumatic events may include crimes, natural disasters, accidents, war or conflict, or other threats to life. It could be an event or situation that you experience yourself or something that happens to others, including loved ones.

    PTSD or an OSI causes intrusive symptoms such as re-experiencing the traumatic event. Many people have vivid nightmares, flashbacks, or thoughts of the event that seem to come from nowhere. They often avoid places, people, conversations, or even things that remind them of the event—for example, someone who was hurt in a car crash might avoid driving.


    PTSD or an OSI can make people feel very nervous or ‘on edge’. Many feel startled very easily, have a hard time concentrating, feel irritable, or have problems sleeping well. They may often feel like something terrible is about to happen, even when they are safe. Some people feel very numb and detached. They may feel like things around them aren’t real, feel disconnected from their body or thoughts, or have a hard time feeling emotions.  People also experience a change in their thoughts and mood related to the traumatic event. For some people, alcohol or drugs can be a way to cope with PTSD or an OSI.

Why does PTSD not affect everyone equally?

    While most people experience trauma at some point in their life, not all traumatic experiences lead to PTSD. We aren’t sure why trauma causes PTSD or an OSI in some people but not others, but it’s likely linked to many different factors. This includes the length of time the trauma lasted, the number of other traumatic experiences in a person’s life, their reaction to the event, and the kind of support they received after the event.

    Trauma is not always a single event in the past. Some trauma, particularly repeated acts like abuse or trauma during wartime, can impact a person’s life far beyond the symptoms of PTSD. Some use other terms like ‘complex PTSD’ to describe these experiences.

Videos on PTSD 

For Further Detail:

Read up on PTSD or OSI in the OSI-CAN Manual


OSI-CAN Target Demographic

The target demographic of OSI-CAN are but are not limited to: former and serving members of the Canadian Armed Forces, Allied Armed Forces, the Royal Canadian Mounted Police and Frontline Protectors --- Municipal Police Services, CN Police Services, Emergency Medical Services, Fire Protection Services, Wildland Firefighters, Hospital Trauma personnel, Nurses, Healthcare Workers, Crown Prosecutors, Social Workers, Animal Control Officers, Coroners, Indigenous Emergency Management, Victim Services Personnel, Emergency Communications Specialist, Crisis Management Workers (such as Mobile Crisis, etc), Corrections Officers, “Volunteer” First Responders, Conservation Officers, Tow Truck drivers, and private sector First Responders.  Persons who in the performance of their jobs are exposed to criminal acts of Trauma. We also provide supports to the spouses and significant others of those exposed to such trauma.  This demographic was chosen due to the commonality of experiences they share through the service they provide to the country and community. We have a special interest and support volunteer first responders as they may not have proper access to support.

Treatment Sessions in Private or in a Group

Our mission is to inspire hope and contribute to the continuous well-being and recovery process of Veterans and Front Line Protectors across Canada.


We seek to empower and encourage them to strive for recovery through peer and professional support while creating greater public awareness.

We at OSI-CAN do not see PTSD or Post-Traumatic Stress Disorder as a Disorder, we see it as an Injury you can recover from.  If you are suffering from the symptoms of an Occupational or Operational Stress Injury, then a PTSD or PTSI diagnosis is not required to get our help

OSI-CAN is a program of:

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In Partnership with:

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With the Support of:

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