Gender Differences in Posttraumatic Stress Disorder

7/27/2019 Gender Differences in Posttraumatic Stress Disorder

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Article

1486 Am J Psychiatry 158:9, September 2001

Gender Differences in Posttraumatic Stress DisorderAfter Motor Vehicle Accidents

Carol S. Fullerton, Ph.D.

Robert J. Ursano, M.D.

Richard S. Epstein, M.D.

Brian Crowley, M.D.

Kelley Vance, M.P.H.

Tzu-Cheg Kao, Ph.D.

Angela Dougall, Ph.D.

Andrew Baum, Ph.D.

Objective: Women have higher rates of

posttraumatic stress disorder (PTSD) thanmen. The authors examined prior trauma,

PTSD, major depression, anxiety disorder

not including PTSD, and peritraumatic dis-

sociation; current peritraumatic dissocia-

tion; and passenger injury as possible ex-

planations for the different rates of acute

PTSD in women and men after a serious

motor vehicle accident.

Method: Subjects age 1865 years who

had been in a serious motor vehicle acci-

dent (N=122) were assessed with the

Structured Clinical Interview for DSM-III-R

and the Peritraumatic Dissociative Experi-

ences QuestionnaireRater Version 1month after the accident.

Results: Women did not differ from men

in meeting the overall reexperiencing cri-

terion for a diagnosis of PTSD (criterion B),

but women were at greater risk for the

specific reexperiencing symptoms of in-

tense feelings of distress in situations simi-

lar to the motor vehicle accident and phys-

ical reactivity to memories of the motor

vehicle accident. Women were 4.7 times

more likely than men to meet the overall

avoidance/numbing criterion (criterion C)and 3.8 times more likely to meet the

overall arousal criterion (criterion D).

Women were more likely than men to re-

port the criterion C symptoms of avoiding

thoughts and situations associated with

the accident, loss of interest in significant

activities, and a sense of foreshortened fu-

ture and the criterion D symptoms of trou-

ble sleeping, difficulty concentrating, and

exaggerated startle response. Multiple lo-

gistic regression analysis indicated that the

gender differences in acute PTSD were not

associated with prior trauma, PTSD, peri-

traumatic dissociation, major depression,

or anxiety disorder not including PTSD or

with passenger injury. However, peritrau-

matic dissociative symptoms at the time of

the accident were associated with a signifi-

cantly higher risk for acute PTSD in women

than in men.

Conclusions: Gender differences in peri-

traumatic dissociation may help explain

differences in risk for PTSD and for some

PTSD symptoms in women and men.

(Am J Psychiatry 2001; 158:14861491)

Motor vehicle accidents are common yet unex-pected traumatic events. In 1997 there were more than 13

million motor vehicle accidents in the United States, re-

sulting in 1.5 million serious injuries and more than 38,000

deaths (1). Recent studieshave shown substantial psychi-

atric morbidity after serious motor vehicle accidents, with

rates of acute posttraumatic stress disorder (PTSD) rang-

ing from 34% to 39% (2, 3). The risk for acute PTSD after a

motor vehicle accident is 4.64 times greater for women

than men (3). Epidemiological studies in the general pop-

ulation also indicate higher rates of PTSD in women than

in men (47). In general, women are 2.382.49 times morelikely to develop lifetime PTSD than men after exposure to

similar traumas (7, 8).

Several studies have suggested risk factors for the devel-

opment of PTSD that might explain the different rates of

PTSD in men and women. People with a history of major

depression are at greater risk for PTSD after all types of

trauma (5) and after a serious motor vehicle accident (2).

Prior trauma, prior PTSD, and prior major anxiety disorder

other than PTSD are also significant risk factors for the de-

velopment of PTSD after a motor vehicle accident (2, 3). In

addition, passenger injury has been suggested as a predic-

tor of PTSD after a motor vehicle accident (3). Those who

experience peritraumatic dissociation at the time of a mo-

tor vehicle accident are 4.12 times more likely to develop

acute PTSD and 4.86 times more likely to go on to chronic

PTSD (3). Each of these risk factors may lead to gender dif-

ferences in the rate of PTSD either because the risk factors

occur at different rates in men and women or because of

fundamentally different neurobiological or psychological

factors related to these risk factors in women and men. Re-

cent findings indicating improvement in PTSD symptomsin women taking sertraline but not in men taking the med-

ication also suggest fundamental gender differences in

PTSD (9, 10).

Few empirical studies have specifically examined these

risk factors as possible explanations for the different rates

of PTSD in men and women. In a large study of a health

maintenance organization population, preexisting major

depression or any anxiety disorder not including PTSD

(examined as a single variable) increased vulnerability for


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Am J Psychiatry 158:9, September 2001 1487

FULLERTON, URSANO, EPSTEIN, ET AL.

lifetime PTSD in women but not in men after control for

the type of trauma. However, this difference was related to

the higher frequency of major depression or anxiety disor-

der among the women in this study (8). In contrast, in the

National Comorbidity Study, after control for the type of

trauma, a history of affective disorder predicted lifetime

PTSD in women but not in men, whereas a history of anx-

iety disorder (not including PTSD) predicted lifetime

PTSD in men but not in women (11). To our knowledge, no

one has examined prior PTSD, peritraumatic dissociation,

or passenger injury as possible explanations of the gender

difference in PTSD.

To better understand gender differences in PTSD, we as-

sessed a group of 122 subjects who had been in motor ve-

hicle accidents. We report here on the following variables

as possible explanations for the different rates of PTSD in

men and women: prior trauma, PTSD, major depression,

anxiety disorder, and peritraumatic dissociation; current

peritraumatic dissociation; and passenger injury.

MethodSubjects

The subjects were drivers or passengers in serious motor vehi-cle accidents involving another passenger car, motorcycle, or

truck within the past 2 weeks. Potential participants were at least

18 and not older than 65 years old and resided within a 40-mile ra-dius of the regional trauma center of a major suburban hospital in

a large metropolitan area. Two physicians systematically re-

viewed hospital records and excluded individuals with evidence

of head trauma, coma, or organic brain syndrome identified by aneurological examination, mental status examination, or com-

puterized tomography scan.

A full description of the study methodology has been previ-ously published (3). The majority of the subjects were recruited

from the regional trauma center. Twenty-eight percent were re-cruited through local police reports of severe motor vehicle acci-dents. Recruits from these sources did not differ from the trauma

center recruits in demographic or dependent variables. Approxi-

mately half of the hospital recruits and 25% of recruits from the

police records agreed to participate. The recruits and the refusersdid not differ demographically except that the refusers were less

educated. Of the total of 122 participants, 64 (52.5%) were men

and 58 (47.5%) were women. The majority were white (N=93,76.2%), were not married (N=76, 62.3%), had attended college (N=

89, 73.0%), and reported an income greater than $20,000 per year

(N=69, 56.6%). The mean age at the time of the accident was 35.6

years (SD=13.1). The men and women did not differ in age, edu-cation, marital status, or race. After completely describing the

study and procedures to the subjects, we obtained written in-

formed consent.

Evaluations

At 1 month postaccident we used the Structured Clinical Inter-

view for DSM-III-R (SCID) (12), including the PTSD supplement(13), to assess lifetime and current PTSD, and the Peritraumatic

Dissociative Experiences QuestionnaireRater Version (14) tomeasure both present (immediately after the motor vehicle acci-

dent) and past peritraumatic dissociation. The Peritraumatic Dis-

sociative Experiences Questionnaire is an eight-item scale that

assesses eight peritraumatic symptoms. Clinicians rated subjectsresponses to symptom probes on a scale from 0 to 3 (0=inade-

quate information, 1=absent, 2=subthreshold, and 3=threshold).

The presence of accident-related passenger injuries was deter-

mined (0=no, 1=yes) (3).

The SCID, PTSD supplement, and Peritraumatic Dissociative

Experiences Questionnaire were administered (and tape-re-corded) at the subjects home by one of two senior licensed clini-

cal social workers experienced in the use of the SCID. Half of the

tapes were reviewed by a senior clinician (R.J.U.) on an ongoing

basis to ensure consistent interview procedures and reliability.The average agreement between the two interviewers and the se-

nior clinician on PTSD diagnoses and each of the PTSD symp-toms was excellent (kappa>0.95, p


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PTSD AND GENDER

4.71 times more likely than men to meet the overall avoid-

ance/numbing criterion (criterion C). Examination of

individual criterion C symptoms indicated that women

were 3.75 times more likely than men to report avoiding

thoughts, feelings, activities, or places associated with the

motor vehicle accident; 3.65 times more likely to report

loss of interest in significant activities; and 2.90 times

more likely to experience a sense of a foreshortened fu-

ture. Women were 3.83 times more likely than men to

meet the overall arousal criterion (criterion D) and also

more often reported trouble sleeping (odds ratio=2.52),

difficulty concentrating (odds ratio=2.90), and being easily

startled (odds ratio=4.63).

Gender Differences in Predictors of PTSD

To further examine the relationship of gender and PTSD

1 month after a motor vehicle accident, we used separate

multiple logistic regression analyses to examine peritrau-

matic dissociation related to the motor vehicle accident,prior trauma, prior peritraumatic dissociation, prior PTSD,

prior major depression, prior anxiety disorder not includ-

ing PTSD (i.e., generalized anxiety disorder, panic disorder,

social phobia, agoraphobia, and obsessive-compulsive

disorder), and passenger injury. Because peritraumatic dis-

sociation was related to race (3), we examined all models

by adjusting for race. Women and men did not differ in the

frequency of any of the risk factors except for passenger in-

jury. Passenger injury was more frequent in women than in

men (23 of 58 women [39.7%] and 13 of 64 men [20.3%])

(2=4.98, df=1, p


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than men to develop PTSD at 1 month (Wald 2=13.95, df=

1, p=0.0002, 95% CI=2.6623.2). However the interaction

of gender and prior peritraumatic dissociative symptoms

was not significant ( Wald 2=0.03, df=1, p=0.87, odds ra-

tio=0.84, 95% CI=0.116.74), suggesting that the gender

difference in 1-month PTSD was not due to prior peritrau-

matic dissociation.

Prior trauma and prior PTSD. Fifty-two individuals

(42.6%) reported having experienced a traumatic eventsometime during their lifetime, before the motor vehicle

accident. After adjusting for the effects of prior trauma,

gender remained a significant predictor of 1-month PTSD

(Wald 2=11.41, df=1, p=0.0007, odds ratio=10.61, 95% CI=

2.741.77). However the interaction of gender and prior

trauma was not significant (Wald 2=0.37, df=1, p=0.54,

odds ratio=0.57, 95% CI=0.093.51), indicating that the

gender difference in 1-month PTSD was not due to prior

trauma.

Thirteen subjects (10.7%) had a history of PTSD before

their motor vehicle accident. Even after adjusting for prior

PTSD, women had a 9.24-fold greater risk than men of 1-

month PTSD (Wald 2=15.80, df=1, p=0.0001, 95% CI=

3.0927.68). The interaction of gender and prior PTSD was

not significant (Wald 2=1.56, df=1, p=0.21, odds ratio=

0.14, 95% CI=0.0073.02), suggesting that the gender dif-

ference in 1-month PTSD was not due to prior PTSD.

Prior major depression. Since women have been shown

to be at high risk for major depression, which is a risk fac-

tor for PTSD, we also examined gender differences in 1-

month PTSD after adjusting for prior major depression.

Even after adjustment for prior major depression, women

were at an 11.72 times greater risk of 1-month PTSD than

men (Wald 2=16.77, df=1, p=0.0001, 95% CI=3.6138.08).

The interaction of gender and prior major depression wasnot significant (Wald 2=3.23, df=1, p


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PTSD AND GENDER

Kessler et al. (7) suggested that prior trauma or age at ex-

posure to trauma might explain the gender differences in

PTSD. Since the women and men in our study did not dif-

fer in age at the time of their motor vehicle accident, and

age did not predict PTSD (3), age is not a likely explanation

of the gender differences in PTSD in our study group. Our

findings also indicate that the gender difference in acute

PTSD related to a motor vehicle accident was not due to

passenger injury or prior trauma. Bromet et al. (11), after

controlling for the type of trauma, found that prior trauma

did not explain the gender differences in PTSD. To our

knowledge, no one has previously examined whether prior

PTSD or prior peritraumatic dissociation could explain

the gender difference. Our data indicate that neither of

these trauma-related factors contribute to the gender dif-

ference in PTSD. However, these results must be inter-

preted cautiously because of the low rate of prior PTSD

and prior peritraumatic dissociation in our study group.

Rates of major depression were similar for the men and

women in our study group. Most often women in the gen-

eral population have been found to be at greater risk fordepression than men (7, 17). Since we found no difference,

it may be that depressed women are less likely to drive or

to be in a serious motor vehicle accident or, alternatively,

that depressed men are more likely to be driving or in a se-

rious accident. Regardless of these possibilities, our analy-

ses indicate that neither prior major depression nor prior

anxiety disorder not including PTSD explained the gender

difference in rates of PTSD. This is similar to the finding of

Breslau et al. (8) that the interaction between gender and

preexisting major depressive disorder or anxiety disorder

not including PTSD had no effect on gender differences in

PTSD. In contrast, Bromet et al. (11), using data from the

National Comorbidity Study, found that women with de-pression were at increased risk of PTSD but men were not,

while a history of anxiety disorder predicted lifetime PTSD

in men but not in women. Both of these studies were

large-scale epidemiologic studies, rather than a more fo-

cused investigation of motor vehicle accidents, and differ

greatly in design from the present study. The present study

used prospective, current assessments with standardized

clinician ratings, in contrast to the large-scale studies,

which relied on subjects recall of past traumatic events

and used trained nonclinician raters. These factors may

contribute to these differences in results. In summary, two

studies found prior depression to be unrelated to the gen-

der differences in PTSD, and one study supported prior

depression as part of the explanation for this difference.

All three studies indicate that prior anxiety disorder can-

not explain the higher rate of PTSD in women.

No previous studies have examined peritraumatic disso-

ciation as a factor in gender differences in PTSD. Women

and men in our study reported the same frequency of peri-

traumatic dissociative symptoms. It is important to note,

however, that peritraumatic dissociative symptoms ap-

peared to carry a different risk for PTSD in women and

men, increasing the risk for PTSD significantly more in

women. This finding may indicate that there are funda-

mental neurobiological differences in peritraumatic disso-

ciation in women and men.

Gender differences in the specific symptoms of PTSD

can indicate avenues for further study and can suggest

specific targets for therapeutic interventions that may

vary between women and men. For example, we found

that although women did not differ from men in meeting

the overall reexperiencing criterion for PTSD (criterion B),

women were at greater risk of intense feelings of distress

when in a situation similar to the motor vehicle accident

and were more likely to report a physical reaction to mem-

ories of the motor vehicle accident. In one model, these

might be the primary symptom differences in PTSD in

men and women. The gender difference in meeting the

overall avoidance criterion (criterion C) and the overall

arousal criterion (criterion D) might be a result of a greater

sensitivity of women to contextual and memory-linked

arousal, which could sustain arousal states after an motor

vehicle accident and lead to chronic avoidance. Replica-tion of findings of gender differences in rates of specific

PTSD symptoms would aid in developing individualized

treatments. The relationship of peritraumatic dissociation

to these specific symptom differences requires further

study. Further studies of gender and PTSD may help de-

fine the gender differences in event-related neurobiology

(e.g., how the outside world changes neurobiological

function) and genetic contributions to brain function.

Such studies are important to our understanding of fun-

damental neurobiology and to clinical care.

Received June 20, 2000; revision received Dec. 12, 2000; accepted

Feb. 21, 2001. From the Department of Psychiatry and the Depart-

ment of Preventive Medicine and Biometrics, Uniformed Services

University of the Health Sciences; and the Department of Behavioral

Medicine and Oncology, University of Pittsburgh Cancer Institute. Ad-

dress reprint requests to Dr. Fullerton, Department of Psychiatry, Uni-

formed Services University of the Health Sciences, 4301 Jones Bridge

Rd., Bethesda, MD 20814-4799; [email protected] (e-mail).

Supported by NIMH grant MH-40106.

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Gender Differences in Posttraumatic Stress Disorder