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Post-Traumatic Stress Disorder
Last edited |
10/21/2008
Post-Traumatic Stress Disorder (PTSD) is a disorder caused by
the experience of a traumatic event
It is characterized by:
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a persistent re-experiencing of the traumatic event,
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a persistent avoidance of stimuli associated with the
trauma,
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a numbing of general responsiveness and
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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 at
10% to 67%.
Posttraumatic Stress Disorder has since been diagnosed in many individuals exposed to a
variety of traumas:
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civilian victims
of war;
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victims of natural disasters such as earthquakes and
tornadoes;
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sexual assault; aggression;
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accidents;
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persons exposed to suicide,
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severe injury to loved ones,
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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:
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personality prior to the trauma,
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social support after exposure to trauma and age at
trauma,
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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:
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specific in Posttraumatic Stress Disorder;
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exacerbated or triggered by Posttraumatic Stress Disorder;
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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.
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.
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Sleep-EVAL
Research
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