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Research Article
DEPRESSION AND ANXIETY 27 : 1077–1086 (2010)
SUBSTANCE USE, CHILDHOOD TRAUMATIC
EXPERIENCE, AND POSTTRAUMATIC STRESS DISORDER
IN AN URBAN CIVILIAN POPULATION
Lamya Khoury, B.S.,
1
Yilang L. Tang, M.D. Ph.D.,
2
Bekh Bradley, Ph.D.,
1,3
Joe F. Cubells, M.D. Ph.D.,
2
and
Kerry J. Ressler, M.D. Ph.D.
1,4,5
Objective: Exposure to traumatic experiences, especially those occurring in
childhood, has been linked to substance use disorders (SUDs), including abuse and
dependence. SUDs are also highly comorbid with Posttraumatic Stress Disorder
(PTSD) and other mood-related psychopathology. Most studies examining the
relationship between PTSD and SUDs have examined veteran populations or
patients in substance treatment programs. The present study further examines
this relationship between childhood trauma, substance use, and PTSD in a sample
of urban primary care patients. Method: There were 587 participants included in
this study, all recruited from medical and OB/GYN clinic waiting rooms at Grady
Memorial Hospital in Atlanta, GA. Data were collected through both screening
interviews as well as follow-up interviews. Results: In this highly traumatized
population, high rates of lifetime dependence on various substances were found
(39% alcohol, 34.1% cocaine, 6.2% heroin/opiates, and 44.8% marijuana). The
level of substance use, particularly cocaine, strongly correlated with levels of
childhood physical, sexual, and emotional abuse as well as current PTSD
symptoms. In particular, there was a significant additive effect of number of types
of childhood trauma experienced with history of cocaine dependence in predicting
current PTSD symptoms, and this effect was independent of exposure to adult
trauma. Conclusions: These data show strong links between childhood
traumatization and SUDs, and their joint associations with PTSD outcome.
They suggest that enhanced awareness of PTSD and substance abuse comorbidity
in high-risk, impoverished populations is critical to understanding the mechan-
isms of substance addiction as well as in improving prevention and treatment.
Depression and Anxiety 27:1077–1086, 2010.
rr
2010 Wiley-Liss, Inc.
Key words: African-American; minority; trauma; childhood maltreatment;
psychiatry; alcohol; cocaine; opiate; Marijuana
INTRODUCTION
Traumatic life experience, such as physical and sexual
abuse as well as neglect, occurs at alarmingly high rates
and is considered a major public health problem in the
Published online 3 November 2010 in Wiley Online Library
(wileyonlinelibrary.com).
DOI 10.1002/da.20751
The authors report they have no financial relationships within the
past 3 years to disclose.
Received for publication 9 June 2010; Revised 10 August 2010;
Accepted 14 August 2010
Correspondence to: Kerry J. Ressler, Howard Hughes Medical
Institute, Department of Psychiatry and Behavioral Sciences,
Yerkes Research Center, Emory University, 954 Gatewood Dr,
Atlanta, GA 30329. E-mail: kressle@emory.edu
1
Department of Psychiatry and Behavioral Sciences, Emory
University School of Medicine, Atlanta, Georgia
2
Department of Human Genetics, Emory University School of
Medicine, Atlanta, Georgia
3
Atlanta VA Medical Center, Decatur, Georgia
4
Howard Hughes Medical Institute, Chevy Chase, Maryland
5
Yerkes National Primate Research Center, Atlanta, Georgia
rr
2010 Wiley-Liss, Inc.
United States.
[1,2]
Early trauma exposure is well known
to significantly increase the risk for a number of
psychiatric disorders in adulthood, although many who
had childhood trauma exposure are quite resilient. The
current study is focused on history of childhood
traumatic experiences. Ample evidence has shown that
childhood trauma compromises neural structure and
function, rendering an individual susceptible to later
cognitive deficits and psychiatric illnesses, including
schizophrenia, major depression, bipolar disorder,
Posttraumatic Stress Disorder (PTSD), and substance
abuse.
[3–8]
Particularly, the link between trauma
exposure and substance abuse has been well-estab-
lished. For example, in the National Survey of
Adolescents, teens who had experienced physical or
sexual abuse/assault were three times more likely to
report past or current substance abuse than those
without a history of trauma.
[9]
In surveys of adolescents
receiving treatment for substance abuse, more than
70% of patients had a history of trauma exposure.
[10,11]
Furthermore, some studies showed that there is a
‘‘dose’’ or ‘‘building block’’ effect of stress load or
trauma on the severity of psychopathology, which is
not restricted to PTSD.
[12–14]
This collection of studies
suggest that a simple dose–response model may not be
sufficient on its own to explain PTSD risk, but that
PTSD diagnosis is likely once an individual passes a
certain stress load threshold regardless of other factors.
Weber et al.
[12]
found that stress load in childhood in
particular was related to both the number and severity
of depressive and PTSD symptoms in patients with
these disorders. Thus, trauma load during the stress-
sensitive period of childhood may be especially
important when considering psychiatric outcomes.
The effects of different types of trauma on psycho-
pathology have also been examined,
[15,16]
suggesting
the effect of trauma may sometimes be type-specific.
For example, Powers et al.
[15]
found that childhood
emotional abuse and neglect were more predictive of
adult depression than physical or sexual abuse. Gender
may also play an important role in behavioral and
psychiatric outcomes of different types of childhood
trauma. However, the potential differential role of type
of childhood maltreatment on substance abuse in a
high-risk population remains unclear.
COMORBIDITY OF PTSD AND SUBSTANCE
USE DISORDER
Studies have also shown that there is high comorbidity
between PTSD with substance abuse disorders
[3,11,17–20]
and other mental disorders. Breslau et al., in particular,
found that exposure to traumatic experience did not
increase the risk of substance problems independently of
PTSD symptomology. Additionally, evidence has shown
that the correlation between trauma and substance abuse
is particularly strong for adolescents with PTSD. Up to
59% of young people with PTSD subsequently develop
substance abuse problems.
[11,21–23]
This seems to be an
especially strong relationship in girls.
[24]
Others found
that alcohol and drug consumption was associated with
greater PTSD symptoms 1 year after a disaster,
[25]
Additionally, women who used drugs were found to have
significantly higher mean scores for total PTSD symptom
severity and were more likely to meet the criteria for a
diagnosis of PTSD compared to nonusers.
[26]
Early traumatic experience may increase risk of
substance use disorders (SUDs) because of attempts
to self-medicate or to dampen mood symptoms
associated with a dysregulated biological stress
response. On the other hand, early adolescent onset
of substance use or abuse may further disrupt the
biological stress response by increasing plasma cortisol
levels, thus additionally contributing to risk for PTSD
and comorbid depressive symptoms.
[27]
Timing and
relative ages of onset are also important when further
characterizing this comoribidity between substance
abuse and PTSD. Researchers have reported that in
cocaine-dependent patients whose PTSD precedes
substance abuse, the trauma is most commonly child-
hood abuse, whereas in those whose substance abuse
precedes PTSD onset, the trauma is most commonly
associated with the procurement and use of sub-
stances.
[28]
Some suggest that the comorbidity of
PTSD with substance abuse may represent a shared
genetically mediated vulnerability to psychopathology
after trauma exposure.
[24,29]
Gender differences in trauma-related risk factors for
alcohol and drug abuse have also been reported. One
study,
[30]
based on data from adolescent samples,
suggests that traumatic event exposure increases risk
for SUDs for young women, but not young men.
Another study
[31]
also suggests the existence of a
gender difference in comorbidity: in men, drug use
preceded the exposure to an event, while in women, the
onset age for both drug use and exposure to an event
were nearly identical.
The current body of literature regarding substance
abuse and PTSD has mostly focused on either military
or veteran populations or on treatment-seeking sub-
stance-dependent individuals. The current study seeks to
extend these findings to a civilian medical population,
which will include more females, and to patients who are
not associated with a treatment-seeking population for
substance use. Additionally, trauma exposure assessments
in most of the published studies are relatively simple;
questionnaires used in the current study—such as the
Early Trauma Inventory (ETI) and the Traumatic Events
Inventory (TEI)—can provide more extensive informa-
tion on trauma history. Finally, most studies report
substance use, abuse, or dependence as categorical
variables, and few have dealt with the severity of SUDs
or with the degree of substance exposure. The current
study deals with continuous variables of substance
exposure that take into account frequency, duration,
and amount used during the period of heaviest use.
In the current study, we examined and extended
findings showing the links between childhood trauma
1078 Khoury et al.
Depression and Anxiety
exposure, substance use, and PTSD. We assessed
indications of a dosage effect of trauma, where
higher levels of childhood traumatization might lead
to both increased substance use and PTSD sympto-
mology. We hypothesize that, like the findings of
Breslau et al.
[19]
childhood trauma will not predict
substance use independently of PTSD symptoms.
However, we do hypothesize that childhood trauma
will contribute to increased substance use and
PTSD symptoms independently of adult trauma
exposure. Finally, we examined evidence of an additive
relationship between childhood trauma and substance
use problems in predicting the level of PTSD
symptomology.
METHODS
SUBJECTS/RESEARCH SETTING
All enrolled participants gave written informed consent, and the
study was approved by Emory University Institutional Review Board.
All potential participants were approached by the research staff at the
waiting rooms of the Grady Memorial Hospital General Medical and
OB/GYN Clinics, in Atlanta, GA. Subjects in this study were from an
ongoing molecular genetics project.
[28,32–34]
The inclusion criteria
were: (1) At least 18 years old, male or female; (2) Able to give
informed consent and willing to participate in day of interviews.
Exclusion criteria included: (1) Mental retardation (diagnosis in clinic
chart); (2) Chart diagnosis of a psychotic disorder. Subjects were
reimbursed for their time and effort in the study.
ASSESSMENTS
All patients who met eligibility criteria and provided consent
completed a battery of clinician-administered self-report assessments,
which included a demographic form and other basic data, such as
subject age, self-identified race, marital status, education, income,
and employment. Basic data included, but were not limited to,
information related to comorbid psychiatric diagnostic status, family
history for psychiatric disorders, past and current substance abuse,
stress, and legal issues, etc. To address variation in literacy of
participants, all questions were read aloud and answers were recorded
by the interviewer. Subjects additionally completed the following
interviews:
1. The modified PTSD Symptom Scale (mPSS) is a 17-item interview
used to aid in the detection and diagnosis of PTSD symptoms in
the 2-week period prior to interview.
[28,35,36]
The structure and
content of the mPSS mirror the DSM-IV criteria for PTSD. The
psychometric properties of the mPSS indicate that the mPSS has
satisfactory internal consistency, high test–retest reliability, and
good concurrent validity. The current study examined mPSS total
score as well as totals for each symptom cluster.
2. The TEI
[37]
is a 14-item screening instrument for lifetime history
of traumatic events. For each traumatic event, the TEI assesses
experiencing and witnessing separately. It also assesses the
confrontation of traumatic events where appropriate. In addition,
the TEI also asks the number of times that each event has
occurred; age at self-perceived ‘‘worst’’ instance for a given
traumatic event; and feelings of helplessness or horror for each
traumatic event. The TEI was used in this investigation to assess
and control for level of adult trauma exposure.
3. The ETI
[38]
evaluates history of childhood physical, sexual, and
emotional abuse, and it was administered during follow-up
diagnostic interviewing. For each item, age of first occurrence,
frequency of occurrence, as well as most common perpetrator is
asked. For each type of abuse (physical, sexual, or emotional),
scores for total number of types (items endorsed) and total
frequency were generated, and these were multiplied to give a
comprehensive continuous score for each. The number of types
for each of the three abuse types was summed to give a total
childhood abuse type score; four quartile groups for childhood
trauma were identified based on this total type score.
4. The Kreek–McHugh–Schluger–Kellogg scale (KMSK scale)
[39]
quantifies self-exposure to opiates, cocaine, alcohol, tobacco, and/or
marijuana use. Each section of the KMSK scale assesses the frequency,
amount, and duration of use of a particular substance during the
individual’s period of greatest consumption (lifetime) and in the 30
days prior to testing (current), andthesethreevaluesweresummedto
give lifetime and current total scores. Using a similar sample from the
same larger study, total lifetime KMSK scores were tested against
dependence diagnoses determined by the Structured Clinical Inter-
view for DSM-IV (SCID) to establish cutoff scores for each
substance.
[40]
A receiver operating characteristics (ROC) analysis
was performed to find the best cutoff score for alcohol, cocaine,
opiates, and marijuana dependence. The levels of sensitivity and
specificity for each possible cutoff score were determined from the
ROC graph, and the cutoff scores with the highest sum total of
sensitivity and specificity were found to be the best. Additionally, a w
2
analysis was used to find the best cutoff scores; presence or absence of
dependence was assigned according to each possible KMSK score for
each substance, and these assignments were compared to those
determined by SCID interview in a two-by-two contingency table.
For alcohol, cocaine, and marijuana, the cutoff scores determined to
be best by both ROC analysis and w
2
analysis were the same (11, 9,
and 8, respectively). The best cutoff score for opiate dependence
differed depending on the method (four using sensitivity/specificity
analysis and seven using w
2
analysis). The more conservative opiate
dependence cutoff score of 7 was shown to have a substantially higher
positive predictive potential than 4, with only a slight decrease in
negative predictive potential (NPP). Thus, the cutoff scores
determined by these methods for alcohol (11), cocaine (9), marijuana
(8), and heroin/opiates (7) determined the dependence groups used in
the current study.
5. Beck Depressive Inventory (BDI) is a 21-item interview used to
detect the presence of depressive symptoms in the 2-week period
prior to testing.
[41]
Each item is rated on the severity of that
specific symptom. The current study uses the BDI total score
variable in certain analyses to control for the presence of current
depressive symptoms.
ANALYSIS
All analyses were performed using SPSS 17.0 software. Descriptive
statistics on demographics were calculated and expressed in terms of
the total number of subjects and percentages of the sample as a
function of gender and a particular characteristic. Gender differences
for demographic variables and measure characteristics were deter-
mined using student t-tests and w
2
analyses where appropriate. We
used two-tailed Pearson’s correlations to show the associations
between severity of childhood trauma exposure and levels of
substance exposure and PTSD symptoms. Univariate analyses were
used to examine differences in PTSD symptom level between
substance dependence groups, as well as between the childhood
trauma quartile groups. Further univariate analyses examined trends
in substance exposure across the four childhood trauma groups, with
post-hoc analyses controlling for adult trauma exposure and PTSD
symptomology.
1079Research Article: Link Between Childhood Traumatization and SUD
Depression and Anxiety
RESULTS
SAMPLE CHARACTERISTICS
A total of 587 participants were included in this study,
with a greater number of females (N5359, 61.2%) than
males (N5228, 38.8%). Table 1 shows demographic
information for the entire sample as well as the
significant differences between males and females.
The mean and standard deviations of the main outcome
variables in this sample are also indicated (Table 2).
TABLE 1. Demographics
Total sample N5587 Males N5228 Females N5359
Age
—mean (SD) 42.35 (12.72) 45.42 (10.96) 40.39 (13.38)
Race/ethnicity N5578 N5224 N5354
Black 527 (91.2) 203 (90.6) 324 (91.5)
Non-black 51 (8.8) 21 (9.4) 30 (8.5)
Education
N5577 N5224 N5353
o12th Grade 136 (23.8) 37 (16.5) 99 (28.0)
High school/GED 240 (41.5) 100 (44.6) 140 (39.7)
Some college/tech 130 (22.5) 54 (24.1) 76 (21.5)
Tech school grad 23 (4.0) 9 (4.0) 14 (4.0)
College grad or higher 48 (8.4) 24 (10.7) 24 (6.8)
Relationship status
N5575 N5223 N5352
Single, never married 331 (57.6) 118 (52.9) 213 (60.5)
Married/domestic partner 67 (11.6) 33 (14.8) 34 (9.7)
Divorced 100 (17.4) 54 (24.2) 46 (13.1)
Separated 45 (7.8) 17 (7.6) 28 (8.0)
Widowed 32 (5.6) 1 (0.4) 31 (8.8)
Monthly income N5564 N5221 N5343
o1,000 405 (71.8) 162 (73.3) 244 (71.1)
1,000–1,999 111 (19.7) 39 (17.6) 72 (21.0)
42,000 48 (8.5) 21 (9.5) 27 (7.9)
Currently unemployed
449/578 (77.7) 185/224 (82.6) 264/354 (74.6)
Current Disability Support
149/576 (25.9) 70/222 (31.5) 79/354 (22.3)
Ever been Arrested
370/577 (64.1) 187/224 (83.5) 183/353 (51.8)
Ever been in jail
347/577 (60.1) 175/224 (78.1) 172/353 (48.7)
Ever been in prison
96/574 (16.7) 70/223 (31.4) 26/351 (7.4)
Ever had psychiatric hospitalization 108/573 (18.8) 40/222 (18.0) 68/351 (19.4)
N/Total Nfor each item (%) for each demographic variable.
Po.05;
Po.001 for gender differences.
TABLE 2. Measure characteristics: mean (SD) for each variable
Total sample Males Females
KMSK total scores
Alcohol (lifetime)
Alcohol (current)
7.99 (4.47)
2.70 (3.68)
9.72 (3.61)
3.35 (4.45)
6.84 (4.62)
2.33 (3.27)
Cocaine (lifetime)
Cocaine (current)
5.22 (6.50)
0.15 (1.03)
6.87 (6.62)
0.29 (1.54)
4.18 (6.22)
0.06 (0.54)
Heroin/opiate (lifetime)
Heroin/opiate (current)
0.81 (2.48)
0.13 (1.25)
1.24 (3.08)
0.34 (2.05)
0.54 (1.96)
0(0)
Marijuana (lifetime)
Marijuana (current)
6.01 (5.13)
1.23 (2.92)
7.70 (5.03)
1.28 (3.13)
5.14 (4.96)
1.19 (2.80)
Tobacco (lifetime)
Tobacco (current)
6.93 (4.90)
3.10 (3.80)
7.72 (4.63)
3.67 (3.83)
6.42 (5.0)
2.77 (3.76)
ETI type
frequency scores
Physical Abuse 35.41 (49.49) 39.45 (54.49) 32.85 (45.93)
Sexual abuse
33.15 (84.99) 21.47 (64.79) 40.58 (94.97)
Emotional abuse
55.21 (74.50) 47.40 (69.46) 60.17 (77.22)
MPSS scores
Total 13.25 (12.32) 12.48 (12.13) 13.76 (12.44)
Intrusive 3.19 (3.83) 2.81 (3.66) 3.43 (3.92)
Avoidance/numbing 5.40 (5.52) 5.34 (5.51) 5.43 (5.54)
Hyperarousal 4.70 (4.46) 4.36 (4.25) 4.92 (4.59)
Po.05;
Po.01;
Po.001 for gender differences.
1080 Khoury et al.
Depression and Anxiety
Rates of lifetime substance dependence, as deter-
mined by KMSK cutoff scores, were high in this
sample. Marijuana was the most common substance of
abuse with 44.8% of a subset of 373 participants who
completed that section of the questionnaire falling in
the dependency group. Alcohol was the next most
common (39%), followed by cocaine (34.1%), and then
heroin/opiates (6.2%).
CHILDHOOD TRAUMA AND SUBSTANCE
USE
Table 3 demonstrates a strong association between
adverse childhood experience (type frequency score)
and levels of exposure to various substances both
currently and during the period of heaviest use. Gender
differences in substance use correlates of the different
types of childhood abuse are also observed. In women,
sexual abuse was significantly linked to lifetime cocaine
(Po.001) as well as marijuana exposure (Po.01).
Physical abuse in men significantly correlates with
current cocaine and lifetime/current heroin use
(Po.01), while in women it is linked to lifetime cocaine
and marijuana use (Po.01). Emotional abuse in men
significantly correlates to current heroin exposure
(Po.01), whereas in women it is linked to heavier
lifetime cocaine use (Po.01).
Analysis of childhood trauma quartiles, which
combined all three types of abuse, demonstrated
increased levels of lifetime alcohol (F55.97,
Po.001), cocaine (F53.90, Po.01),and marijuana
(F59.18, Po.001) exposure with increased trauma
load (Fig. 1). Significant group differences between
specific quartiles are indicated. These analyses con-
trolled for age and sex; when adult trauma exposure
was introduced as a covariate, only the increases in
alcohol (F52.92, Po.05) and marijuana use
(F55.162, Po.01) remained statistically significant.
The increase in these two substances additionally
remained significant after independently controlling
for current PTSD symptom level (Alcohol: F53.61,
Po.05; Marijuana: F56.57, Po.001). While heroin
exposure did appear to increase overall across the four
quartiles as well, this trend did not reach statistical
significance. However, a significant group difference in
heroin exposure was observed between the second and
fourth quartiles.
PTSD AND SUBSTANCE DEPENDENCE
Differential levels of current PTSD symptomology
between those with and without lifetime substance
dependence are demonstrated in Figure 2. After
controlling for age and sex, lifetime cocaine depen-
dence was significantly associated with a higher PSS
total score (F526.90, Po.001) as well as symptom
level across all three clusters (Intrusive: F518.46,
Po.001; Avoidance/Numbing: F520.91, Po.001; and
Hyperarousal: F523.07, Po.001). Lifetime marijuana
dependence was also associated with PSS total
(F510.12, Po.01) and symptoms across all clusters
(Intrusive: F54.16, Po.05; Avoidance/Numbing:
F511.25, Po.01; and Hyperarousal: F57.72,
Po.01). Lifetime alcohol dependence was associated
with PSS total (F56.48, Po.05), avoidance/numbing
(F56.92, Po.01), and hyperarousal symptoms
(F54.46, Po.05). Lifetime heroin dependence was
not significant in predicting current PTSD levels. After
controlling for current level of depressive symptoms,
only the marijuana dependence group differences
between PSS total, intrusive, and hyperarousal scores
remained significant. No other substance dependence
group differences were significant after depressive
symptoms were taken into account.
CHILDHOOD TRAUMA, SUBSTANCE
DEPENDENCE, AND PTSD
Using a two-tailed Pearson correlation, the total
number of types of childhood trauma correlated
significantly with current total PTSD symptoms in
TABLE 3. Correlations between childhood abuse
type
frequency score and substance use
All Males Females
Physical abuse
Alcohol (life) ]
Alcohol (current
r5.110
r5.010
r5.065 r5.112
Cocaine (life) ]
Cocaine (current)
r5.156
r5.190
r5.136 r5.155
Heroin/Opiate (life) ]
Heroin/Opiate (current) ]
r5.123
r5.251
r5.207
r5.352
r5.003
Marijuana (life) ]
Marijuana (current) ]
r5.199
r5.043
r5.186
r5.154
r5.196
r5.048
Tobacco (life) ]
Tobacco (current)
r5.148
r5.031
r5.053 r5.205
Sexual abuse
Alcohol (life) ]
Alcohol (current)
r5.081
r5.129
r5.103 r5.128
Cocaine (life) ]
Cocaine (current)
r5.127
r5.004
r5.016 r5.235
Heroin/Opiate (life) ]
Heroin/Opiate (current) ]
r5.038
r5.011
r5.019
r5.014
r5.085
Marijuana (life) ]
Marijuana (current) ]
r5.146
r5.039
r5.071
r5.098
r5.216
r5.008
Tobacco (life) ]
Tobacco (current)
r5.129
r5.018
r5.054 r5.184
Emotional abuse
Alcohol (life) ]
Alcohol (current)
r5.093
r5.069
r5.098 r5.140
Cocaine (life) ]
Cocaine (current)
r5.108
r5.071
r5.109 r5.140
Heroin/Opiate (life) ]
Heroin/Opiate (current) ]
r5.045
r5.144
r5.153
r5.285
r5.029
Marijuana (life) ]
Marijuana (current)
r5.115
r5.005
r5.142 r5.142
Tobacco (life) ]
Tobacco (current)
r5.137
r5.021
r5.053 r5.201
Po.01;
Po.001;
]
Po.05 for child abuse gender interaction
term. Only those with significant interaction were stratified by gender.
1081Research Article: Link Between Childhood Traumatization and SUD
Depression and Anxiety
this sample (r5.399, Po.001). Childhood trauma
quartile analyses demonstrate increased levels of PTSD
symptomology, both in PSS total score (F527.92,
Po.001) as well as across the symptom clusters
(Intrusive: F518.43, Po.001; Avoidance/Numbing:
F525.18, Po.001; Hyperarousal: F519.56, Po.001)
with higher level of childhood trauma exposure. These
relationships remained significant after controlling for
age, sex, and level of adulthood trauma exposure.
Further analyses on the effect of childhood trauma
load on current PTSD symptoms took into account
substance dependence history. Across all four quartiles,
history of cocaine dependence was associated with
higher PSS scores (Fig. 3; F513.50, Po.001). This
relationship remained significant after controlling for
age, sex, and adulthood trauma exposure. However,
this relationship was no longer significant after current
depressive symptomology was included in the model.
Closer examination of each quartile showed significant
substance dependence group differences in mean PSS
score at the second (F56.66, Po.05), third (F54.13,
Po.05), and fourth (F57.43, Po.01) quartiles only.
DISCUSSION
The current study confirms previous findings of a
strong relationship between adverse childhood experi-
ence and subsequent substance use and poor mental
health outcomes, particularly PTSD.
[42]
In all subjects,
physical abuse correlated with the use of all substances
examined, while sexual abuse in childhood associated
with cocaine and marijuana use only, suggesting
differential effects of abuse type on substance use.
The findings with regard to sexual abuse appear to be
driven by significant associations in women but not
men; this is consistent with the higher prominence of
childhood sexual abuse in women in this sample.
Figure 1. Substance use across childhood trauma quartiles. Of these four substances, alcohol (F55.97, Po.001), cocaine (F53.90,
Po.01) and marijuana use (F59.18, Po.001) increased significantly across the four childhood trauma quartiles. Significant group
differences in KMSK scores between specific quartiles are indicated on each graph. These data suggest a dosage effect of childhood
trauma load on substance exposure, particularly alcohol, cocaine, and marijuana, later on. KMSK, Kreek–McHugh–Schluger–Kellogg.
1082 Khoury et al.
Depression and Anxiety
Additionally, emotional abuse was associated with
cocaine use in the current study.
Examination of the childhood trauma quartiles
shows alcohol, cocaine, and marijuana use significantly
increasing across the four quartiles. This essentially
indicates a progressive effect of trauma load on the
severity of use of these particular substances. While
heroin use did not increase significantly across the
childhood trauma quartiles overall, group differences
were observed between the second and fourth quartiles,
indicating a trend in that direction. It is important to
consider that these childhood trauma quartiles repre-
sent the number of types of childhood abuse experi-
enced; other important factors may include severity and
frequency of abuse, age of first occurrence, as well as
perpetrator identity.
Although we predicted that this effect of multiple
traumatization would not be independent of PTSD
symptoms, alcohol and marijuana (but not cocaine) use
still increased significantly across childhood trauma
quartiles even after controlling for PTSD. Other
researchers
[43]
have found PTSD to be a significant
mediator of the effect of childhood abuse on substance
use problems later on, and we similarly found that
PTSD symptoms may account for cocaine use in
individuals who have experienced childhood trauma.
The absence of this finding for other substances could
be accounted for by the different time periods assessed;
since we looked at lifetime substance exposure but
current PTSD symptoms, it is possible that the use of
alcohol or marijuana may have been better accounted
for by PTSD symptoms occurring at the same time, or
several years before the onset of substance use
problems as findings by Douglas et al.
[44]
suggest.
Additionally, as hypothesized, childhood trauma con-
tributed to increased alcohol and marijuana use
Figure 2. PTSD symptoms between substance dependence groups. These graphs show differences between PTSD symptom level
between alcohol, cocaine, and marijuana-dependent and non-dependent groups. While the differences for cocaine and marijuana
dependence applied across all symptom clusters, those for alcohol dependence applied to all but intrusive symptoms. PTSD,
Posttraumatic Stress Disorder.
1083Research Article: Link Between Childhood Traumatization and SUD
Depression and Anxiety
independently of adult trauma exposure. However, the
effect of childhood trauma load on cocaine use was not
independent of adult trauma, which may be indicative
of adult trauma in this population that is associated
with obtaining and using this particular substance.
A progressive effect of childhood trauma load on
PTSD symptomology was also observed, where child-
hood trauma contributes to higher total PTSD
symptoms as well as higher levels of symptoms in each
cluster. The effect of childhood trauma on PTSD
severity was also found to be independent of adult
trauma. When substance dependence was taken into
account, only cocaine dependence showed a significant
additive relationship with childhood trauma in pre-
dicting PTSD severity. It was also the cocaine-
dependent group that scored significantly higher in
PTSD scores across all clusters. However, these
findings were no longer significant after controlling
for current depressive symptoms, perhaps reflecting the
high comorbidity between PTSD and depression as
well as a strong relationship between depression and
substance use problems. The strong association
between cocaine dependence and PTSD symptoms
may in part be due to the nature of the drug itself; as a
stimulant, cocaine use may contribute to and enhance
hyperarousal symptoms in particular. These findings
can also be understood in the context of a high
prevalence of crack cocaine use in this population.
While marijuana use is also extraordinarily prevalent,
and marijuana dependence did predict higher PTSD
scores across all clusters, caution must be used in
interpreting these results; the KMSK cutoff score
determined for marijuana dependence was the first to
be established for this substance, thus it needs to be
validated further before we can know how useful it is.
Several limitations exist with respect to this study. As
with all similar studies of adult retrospective reporting
of child maltreatment histories, we cannot rule out
possibilities of recall bias in these subjective reports.
Furthermore, we do not currently have sufficient data
with regards to the timing of the trauma, PTSD
symptoms, and substance abuse histories, so that these
data are correlative, but cannot imply direction of
causation. We believe that these effects are general-
izable to urban, traumatized civilian populations at
high risk for substance abuse, but perhaps not to other
populations. Especially given the extremely high
percentage of African Americans in this sample
(91.2%), these findings may not be generalizable to
populations with different racial profiles.
In summary, we find that there are high rates of
lifetime dependence on various substances in this high-
risk population. Additionally, the level of substance use,
particularly cocaine, strongly associated with levels of
childhood physical, sexual, and emotional abuse as well
as current PTSD symptoms. There was a significant
additive effect of number of types of childhood trauma
experienced with lifetime cocaine dependence in
predicting current PTSD symptoms, and this effect
was independent of levels of adult trauma. These data
suggest that enhanced awareness of the comorbidity
between PTSD and substance abuse is critical both in
understanding mechanisms of substance addiction as
well as in improving prevention and treatment.
Acknowledgments. This work was primarily sup-
ported by National Institutes of Mental Health
(MH071537). Support was also received from National
Institute of Mental Health (MH082256 to CFG),
National Institute of Drug Abuse (DA015766 to JFC),
Emory and Grady Memorial Hospital General Clinical
Research Center, NIH National Centers for Research
Resources (M01RR00039), the American Foundation for
Suicide Prevention (RGB) and the Burroughs Wellcome
Fund (KJR). We thank Allen Graham, Justine Phifer,
Daniel Crain, Lauren Sands, Asante Kamkwalala, James
Poole, Sachiko Donley, India Karapanou, and Angelo
Brown for excellent technical support.
Financial Disclosure Statement: There were no com-
mercial sponsors or commercial relationships related to
the current work. All additional past and present
financial ties of the investigators are disclosed herein.
Dr. Ressler has received awards and/or funding support
related to other studies from Burroughs Wellcome
Foundation, NARSAD, NIMH, and NIDA. Dr. Bradley
has received funding from AFSP.
Figure 3. Current PTSD level between cocaine dependence
groups across childhood trauma quartiles. This graph indicates
an additive effect of childhood trauma load and past cocaine
dependence in predicting current PTSD symptom level. Across
all four quartiles, the cocaine-dependent group had significantly
higher PSS scores than the non-dependent group (F513.50,
Po.001). Significant group differences at the second, third and
fourths quartiles are also indicated. PTSD, Posttraumatic Stress
Disorder; PSS, PTSD Symptom Scale.
1084 Khoury et al.
Depression and Anxiety
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