Post-Traumatic Stress Disorder

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Written by Maurice M. Ohayon, MD, DSc, PhD

It is characterized by:

•  a persistent re-experiencing of the traumatic event,

•  a persistent avoidance of stimuli associated with the trauma,

•  a numbing of general responsiveness and

•  persistent symptoms of increased arousal.

History

It was first identified among veterans of the Second World War.

In this specific population, the prevalence of Posttraumatic Stress Disorder has been estimated between 10% to 67%.

Edvard Munch

(1893)The Scream

Posttraumatic Stress Disorder has since been diagnosed in many individuals exposed to a variety of traumas:

•  civilian victims of war;

•  victims of natural disasters such as earthquakes and tornadoes;

•  sexual assault; aggression;

•  accidents;

•  persons exposed to suicide,

•  severe injury to loved ones,

•  and serious life-threatening disease.

Before this study, epidemiological studies in the general population estimated the lifetime prevalence of Posttraumatic Stress Disorder to be from 1% to 14%, depending on the population sampled (3; 17-21).

The one-month prevalence was set at 1% to 2.3% (17-19, 22).

The persistent re-experience of the trauma can take the form of recurrent distressing dreams of the event.

This has lead researchers to study the sleep of subjects with Posttraumatic Stress Disorder.

In 1989, Ross et al. (23) proposed that dysfunctional REM sleep mechanisms could be responsible for the distressing bad dreams reported in Posttraumatic Stress Disorder patients and concluded that sleep disturbances were the hallmark of Posttraumatic Stress Disorder.

This conclusion fueled a growing interest in the study of sleep characteristics in subjects with Posttraumatic Stress Disorder.

Polysomnographic studies have shown a disturbance in phasic Rapid Eye Movement (REM) sleep activity that could be compared to the hyperarousal manifestations observed in subjects with Posttraumatic Stress Disorder during the daytime. This dysregulation of the REM activity manifests as recurrent awakenings that are often preceded by REM sleep (24,25) and bad dreams or anxiety dreams occurring in both REM and non-REM sleep (26, 27).

High motor activity during the sleep of subjects with Posttraumatic Stress Disorder has also been reported during non-REM sleep.

However, other polysomnographic studies failed to replicate these findings (28).

The overwhelming majority of these aforementioned studies have been performed with war veterans, and one investigated the victims of a hurricane.

Posttraumatic Stress Disorder is very often associated with other mental disorders (depressive and anxiety disorders), reaching 80% of cases in some studies.

Furthermore, exposure to trauma alone does not necessarily predict Posttraumatic Stress Disorder, nor does the severity of the traumatic exposure. Individual factors are linked to its development such as:

•  personality prior to the trauma,

•  social support after exposure to trauma and age at trauma,

•  as well as duration and intensity of exposure to trauma

Certain traumas, such as war and rape (32), have a very high likelihood of precipitating Posttraumatic Stress Disorder.
 

Research

The present report examined, in a representative sample of a general population, in what extent sleep disorders are:

• specific in Posttraumatic Stress Disorder;

• exacerbated or triggered by Posttraumatic Stress Disorder;

• related to the traumatic event, to Posttraumatic Stress Disorder or to an associated mental disorder.

Methods

The study was performed with a representative sample of 1,832 respondents aged 15 to 90 years living in the Metropolitan Toronto Area.

Subjects were surveyed by telephone.

The participation rate was 72.8%.
Interviewers used Sleep-EVAL, an expert system specifically designed to conduct epidemiological studies of sleep and mental disorders in the general population.

Results

Overall, 11.6% of the sample reported having experienced a traumatic event, with no difference in the proportion of men and women.
 

Approximately two percent (1.8%) of the entire sample was diagnosed by the system as suffering from a Posttraumatic Stress Disorder at time of interview. The rate was higher for women (2.6%) than for men (0.9%) which translated into an odd ratio of 2.8 (95% C.I.: 1.3 to 6.1).

Posttraumatic Stress Disorder was strongly associated with other mental disorders: 75.7% of respondents with Posttraumatic Stress Disorder received at least one other diagnosis.

Most concurrent disorders (80.7%) appeared after exposure to the traumatic event.

Sleep disturbances also affected about 70% of the Posttraumatic Stress Disorder subjects.

Violent or injurious behaviors during sleep, sleep paralysis, sleep talking, hypnagogic and hypnopompic hallucinations were more frequently reported in the respondents with Posttraumatic Stress Disorder.

Conclusions

Considering the relatively high prevalence of Posttraumatic Stress Disorder and its important comorbidity with other sleep and psychiatric disorders, an assessment of the history of traumatic events should be part of a clinicians routine inquiry in order to limit chronicity and maladjustment following a traumatic exposure.
 

Moreover, complaints of REM related sleep symptoms could be the indication of an underlying problem stemming from a Posttraumatic Stress Disorder.