Losing consciousness can stop you getting posttraumatic stress disorder

Accident victims who suffer a severe head injury are more likely to develop posttraumatic stress disorder if they remain conscious during their ordeal, according to research published in BMC Psychiatry this week. Unconsciousness probably protects people from posttraumatic stress disorder by preventing them from forming memories of their experience.

Current thinking holds that traumatic brain injury alone may be sufficient to protect patients from developing posttraumatic stress disorder, yet this study shows that the protection only arises if patients also lose consciousness.

Judith Glaesser and her colleagues from University of Konstanz, Germany, examined 46 inpatients from Kliniken Schmieder Konstanz that had suffered a traumatic brain injury or a traumatic injury to the spine. They split the patients into two groups depending on how long they had lost consciousness for after their accident: 31 patients had lost consciousness for at least 12 hours; the other 15 had only lost consciousness for an hour at most.

Remaining conscious after the accident made it nine times more likely that the patients would suffer from posttraumatic stress disorder. 27% of the patients who had mostly remained conscious were suffering from the condition, compared to 3% of those who had lost consciousness for more than 12 hours.

To suffer from posttraumatic stress disorder, you need to create a pathological memory based on the traumatic events you experience. The researchers suggest that losing consciousness could be protective, as whilst you are unconscious you cannot form any memories.

The difference in the incidence of posttraumatic stress disorder could not be accounted for by differences in patients’ age at the time of the accident, their current memory function or the severity of the injury they incurred.

This result is perhaps surprising as you could imagine that the more severe the accident, the more likely the victim will suffer posttraumatic stress disorder. But, as the researchers say, “those patients who had experienced loss of consciousness sustained more severe injuries. Since this group was less likely to develop posttraumatic stress disorder, the severity of the injury did not prove to be a contributing factor.”

As the size of this study was relatively small, the researchers stress that a study using a larger number of volunteers will be needed to determine if losing consciousness consistently protects against posttraumatic stress disorder.