Post-traumatic stress disorder (PTSD) can develop after a very stressful, frightening or distressing event.
The type of events that can lead to PTSD include:
- military combat
- serious road accidents
- terrorist attacks
- natural disasters, such as severe floods, earthquakes or tsunamis
- being held hostage
- witnessing a violent death
- violent personal assaults, such as sexual assault, mugging or robbery
PTSD is not usually related to situations that are simply upsetting, such as divorce, job loss or failing exams.
PTSD develops in about 30% of people who witness a traumatic event. It is not fully understood why some people develop the condition after witnessing a traumatic event while others don't. However, there are a number of risk factors that appear to make certain people more likely to develop PTSD.
Risk factors
If you've had depression or anxiety in the past, or you don't receive much support from family or friends, you are more susceptible to developing PTSD after a traumatic event.
There may also be a genetic factor involved in PTSD. For example, having a parent with a mental health problem is thought to increase your chances of developing the condition.
Being abused during childhood is also thought to be another risk factor for PTSD.
Abnormal hormone response
Studies have shown that people with PTSD have abnormal levels of stress hormones.
When in danger, the body produces several natural chemicals, such as adrenalin. In very stressful situations, adrenalin triggers a reaction in the body, which is often known as the "fight or flight" reaction. This helps to deaden the senses and dulls pain.
However, people with PTSD have been found to continue to produce high amounts of fight or flight hormones even when there is no danger. It is thought that this may be responsible for the numbed emotions and feelings of detachment that are experienced by some people with PTSD.
Changes in the brain
The part of the brain responsible for memory and emotions is known as the hippocampus. In people with PTSD, the hippocampus appears different in magnetic resonance imaging (MRI) scans. It is thought that the changes in this part of the brain may be related to memory problems and flashbacks.
If high amounts of stress hormones (such as adrenalin) are produced, the hippocampus can stop working properly, causing repeated flashbacks and nightmares to occur. The malfunctioning hippocampus may prevent flashbacks and nightmares from being properly processed.
If the stress is relieved and the levels of adrenalin return to normal, the brain will begin to repair itself. Over time, the flashbacks and nightmares will gradually disappear.
