Abstract
Background and Objectives
To examine the associations between posttraumatic stress disorder (PTSD) symptoms, stimulant use, and treatment outcomes among dually-diagnosed women.
Methods
Participants were 141 women who participated in a multisite clinical trial of group treatments for PTSD and addictions.
Results
Generalized linear models indicated Seeking Safety (SS; a cognitive-behavioral intervention) was significantly more effective than Women’s Health Education (WHE; a control group intervention) in reducing stimulant use at follow-up among women who were heavy stimulant users at pre-treatment and who showed improvements in PTSD symptoms. There were no significant differences between the interventions among women who were light stimulant users at treatment entry.
Conclusions and Scientific Significance
These findings suggest that integrated treatment of co-occurring PTSD and addictions may be more effective than general health education approaches for heavy stimulant users. Assessment of frequency of stimulant use among individuals with PTSD symptoms may inform treatment selection for this population.
Background and Objectives
The relationship between Posttraumatic Stress Disorder (PTSD) and Substance Use Disorders (SUDs) has been well-documented.1–6 The self-medication hypothesis7–8 posits that individuals use substances as a way to cope with distressing PTSD symptoms. Studies have shown that improvements in PTSD symptoms are often related to subsequent reductions in SUD symptoms whereas the reverse relationship has not been demonstrated.9–12 One limitation of these studies is the focus on PTSD and SUD as global diagnostic categories, which obscures the differential relationships between PTSD symptoms and different types of substances. The present analyses examined the relationships between PTSD symptoms, stimulant use, and treatment outcomes in a sample of dually-diagnosed women who received community based outpatient treatment. Stimulant use may be a risk factor for exacerbation of pre-existing psychiatric disorders; thus understanding more about the interplay between PTSD symptoms and stimulant use may have important implications for treatment interventions.13,14 We predicted that frequency of stimulant use at baseline would be a moderator of PTSD and stimulant use outcomes and that improvements in PTSD symptoms, after receiving treatment, would be associated with decreases in stimulant use at follow-up. We also examined the differential impact of improvements in the three separate PTSD symptom clusters on stimulant use outcomes.
Methods
Participants
Data for these analyses were derived from the “Women and Trauma” study conducted within the Clinical Trials Network (for complete details on procedures see Hien et al.).15 Of the 353 randomized participants, 141 reported stimulant use (cocaine/amphetamines) in the 30 days prior to baseline assessment and were included in these analyses.
Procedures
Eligible participants were randomized into one of two 12-session group interventions (Seeking Safety or Women’s Health Education). Participants completed weekly assessments during treatment and were reassessed at 1-week, 3-, 6-, and 12-months posttreatment. These analyses focused solely on the baseline and posttreatment assessments.
Interventions, training, and fidelity
Seeking Safety (SS)16 is a manualized integrated cognitive-behavioral treatment designed to reduce co-occurring PTSD and SUDs. Women’s Health Education (WHE)17 is a psychoeducational comparison intervention focused on general health topics pertinent to women (e.g., female anatomy and nutrition). Training and Fidelity have been extensively described elsewhere (see Hien et al.15 for a description of the adherence measures and procedures). Internal consistency and inter-rater reliability for both interventions were good to excellent.
All study participants were enrolled in a participating community-based substance abuse treatment program and received treatment-as-usual at the program during the 6-week treatment phase of the study. Participants who dropped from their community based treatment program prior to completing the research treatment but completed at least one follow-up assessment were included in these analyses.
Measures
Basic demographic data (age, race/ethnicity, education, and marital status) were collected at the screening and baseline visits.
The Life Events Checklist,18 a self-report measure, was utilized to assess exposure to a variety of potentially traumatic events.
The Clinician Administered PTSD Scale (CAPS)19,20 is a structured interview, which measures the frequency and intensity PTSD symptoms in the past 30 days and is used as a measure of DSM-IV PTSD diagnosis. The CAPS has three PTSD symptom cluster subscales: 1) re-experiencing, 2) avoidance/emotional numbing, and 3) hyperarousal. PTSD symptom cluster severity scores were calculated by summing the frequency and intensity scores obtained from each subscale items; a total PTSD severity score is obtained by summing the subscale scores. Clinical assessors received formal training in administering the CAPS. Diagnostic reliability checks were conducted on 18% of the audiotaped assessments. Based on 62 baseline assessments, percent agreement between two raters for current PTSD diagnosis was 94%.
The Addiction Severity Index Lite (ASI-Lite)21,22 is a semi-structured clinical interview, which assesses current (past 30-days) alcohol and other substance use. At baseline, the maximum number of days of stimulant use (cocaine and amphetamines) in the 30 days prior to study entrance was calculated and categorized into two levels: light use (used 1–12 days), and heavy use (used 13 or more days). At posttreatment follow-up, stimulant use was categorized into three levels: abstinent (no use), light use (used 1–12 days), and heavy use (used 13 or more days). This is in line with ASI convention of coding more than three days of use per week as heavy use.21
Analyses
Demographic information and psychiatric symptoms by baseline frequency of stimulant use were compared using the t test for continuous variables and chi-square test for categorical variables.
Outcome variables were PTSD symptom severity (total PTSD severity scores and each of the three PTSD symptom cluster scores) as assessed by the CAPS and frequency of stimulant use as assessed by the ASI-Lite. The stimulant use model had two sub-sets; one included the change scores of the total PTSD symptom severity from baseline to each successive follow-up time-point, the possible interactions with treatment, and the baseline values of the outcome measure; and the other controlled for changes in the PTSD symptom clusters scores from baseline to each successive follow-up time-point. Generalized estimating equations (GEEs)23 were used to examine the effect of treatment group (Seeking Safety vs. Women’s Health Education) on the main outcome variables over each successive follow-up time-point for the intention-to-treat (ITT) sample of stimulant users. Pairwise comparisons were applied to detect average group differences during follow-up. Each outcome was modeled as a function of treatment, time of assessment, and baseline value of that outcome. Consistent with the primary outcomes analyses,15 all models included the following a priori baseline covariates: race/ethnicity, age, marital status, and education level. The possible interactions among treatment, the baseline level of the outcome measure, and time were tested and included in the final model only if statistically significant (p < .05).1 Site was tested as an additional fixed effect in each model. Because two sites each had a case with only one follow-up, these two cases were excluded when the site covariate was controlled in the models on categorical outcomes for substance use.
Results
Participant Characteristics
Participants were women with a mean age of 41 years (SD = 9.02). The majority of participants had experienced physical assault (83.6%) and sexual assault (67.9%) during adulthood (See Table 1). There were no significant differences between the light and heavy stimulant users on any of the demographic variables or rates of exposure to traumatic events (p > .05).
Table 1.
Baseline sociodemographics and clinical characteristics stratified by frequency of stimulant use.
| Total (N = 141) | Light Users (n = 79) | Heavy Users (n = 62) | |
|---|---|---|---|
| Age | 41.01 (9.02) | 40.76 (9.58) | 41.33 (8.32) |
| Race/Ethnicity | |||
| African American | 46.10 | 44.30 | 48.39 |
| Caucasian | 28.37 | 30.38 | 25.81 |
| Latina | 9.22 | 7.59 | 11.29 |
| Multi-Racial or Other | 16.31 | 17.72 | 14.52 |
| Marital Status | |||
| Married | 17.02 | 16.46 | 17.74 |
| Single | 36.88 | 43.04 | 50.00 |
| Divorced/Separated | 46.10 | 40.51 | 32.26 |
| Education (Years) | 12.34 (2.12) | 12.33 (2.18) | 12.35 (2.06) |
| Treatment – Seeking Safety (vs. Women’s Health Education) | 53.90 | 56.96 | 50.00 |
| Lifetime Traumatic Events | |||
| Adulthood Physical Assault | 83.57 | 82.05 | 85.48 |
| Adulthood Sexual Assault | 67.86 | 66.67 | 69.35 |
| Childhood Sexual Abuse | 67.63 | 69.23 | 65.57 |
| Childhood Physical Abuse | 53.57 | 50.00 | 58.06 |
| Transportation Accidents | 71.43 | 72.15 | 70.49 |
| Life threatening Illness | 43.57 | 46.84 | 39.34 |
| Stimulant Use (Days in past 30) | 11.68 (10.01) | 3.85 (2.98)* | 21.66 (6.15)* |
| CAPS Severity (Total) | 65.17 (18.62) | 61.92 (18.19)* | 69.31 (18.47)* |
| Re-experiencing Symptoms | 16.82 (6.58) | 16.23 (5.97) | 17.58 (7.26) |
| Avoidance/Numbing Symptoms | 27.04 (9.63) | 25.39 (10.04)* | 29.15 (8.71)* |
| Hyperarousal Symptoms | 21.30 (7.35) | 20.30 (7.06) | 22.58 (7.58) |
Notes. CAPS = Clinician-Administered PTSD Scale, range = 0–136. Items that are marked with an asterisk (*) are significantly different from each other at the p < .05 level.
Relationship between PTSD symptoms and Frequency of Stimulant Use at Baseline
At baseline, the average total PTSD severity score among all participants was 65.17 (SD = 18.62), consistent with severe levels of PTSD.19 Heavy stimulant users had significantly higher total PTSD severity scores than light users (M = 69.31; SD = 18.47 versus M = 61.92; SD = 18.19 respectively, t = 2.38, p = .02). Heavy stimulant users also had significantly higher avoidance/numbing scores compared with light stimulant users (M = 29.15; SD = 8.71 versus M = 25.39; SD = 10.04, respectively, t = 2.33, p = .02).
PTSD Symptoms and Symptom Clusters Outcomes at Follow-up
The final mixed effect analysis revealed no significant treatment effect on total PTSD severity scores during follow-up (χ2 (1) = 0.99, p = 0.32; See Table 2) nor any significant effect of baseline levels of stimulant use (heavy versus light use) on total PTSD severity scores during follow-up (χ2 (1) = 0.07, p = 0.79). Significant effects included time (χ2 (3) = 10.26, p = 0.017), and baseline total PTSD severity scores (χ2 (1) =14.82, p <0.001). For the total sample, the mean total PTSD severity score decreased about 49% from baseline to 1-week after treatment (t = 9.94, p < 0.001), and continuously dropped an additional 9% through 12-month follow-up. Total PTSD severity scores at 12-month follow-up were significantly lower than 1-week posttreatment. (t = 2.98, p < .01).
Table 2.
Unadjusted Comparisons Between the Seeking Safety and Women’s Health Education Groups on Continuous and Categorical Measures of Outcome
| Outcomes | Baseline | Posttreatment | 3-month | 6-month | 12-month |
|---|---|---|---|---|---|
| Means (SD) | |||||
| CAPS Severity Score | |||||
| SS | 62.75 (18.46) | 34.88 (26.80) | 32.40 (23.54) | 29.02 (23.21)* | 25.82 (25.42) |
| WHE | 68.00 (18.54) | 35.16 (24.68) | 37.53 (24.89) | 41.07 (32.43)* | 33.27 (29.25) |
| t-test | 1.68 | 0.05 | 0.95 | 1.99 | 1.27 |
| p-value | 0.10 | 0.96 | 0.35 | 0.05 | 0.21 |
| Stimulant Use (Days in Prior 30 Days) | |||||
| SS | 11.45 (9.92) | 2.41 (4.88) * | 3.00 (5.16) | 4.00 (7.69) | 3.88 (7.49) |
| WHE | 11.95 (10.18) | 5.46 (8.72) * | 6.19 (8.91) | 6.47 (9.97) | 6.03 (9.72) |
| Z-testa | 0.12 | 2.00 | 1.18 | 1.06 | 0.98 |
| p-value | 0.90 | 0.05 | 0.24 | 0.29 | 0.33 |
| Stimulant Use Categories (% and No.) | |||||
| SS | |||||
| Abstinence | 60.98% (N=25) | 51.06% (N=24) | 58.33% (N=28) | 58.00% (N=29) | |
| 1–12 days | 59.21% (N=45) | 31.71% (N=13) | 42.55% (N=20) | 33.33% (N=16) | 30.00% (N=15) |
| 13–30 days | 40.79% (N=31) | 7.32% (N=3) | 6.38% (N=3) | 8.33% (N=4) | 12.00% (N=6) |
| WHE | |||||
| Abstinence | 41.46% (N=17) | 44.44% (N=16) | 48.84% (N=21) | 48.65% (N=18) | |
| 1–12 days | 52.31% (N=34) | 43.90% (N=18) | 33.33% (N=12) | 30.23% (N=13) | 29.73% (N=11) |
| 13–30 days | 47.69% (N=31) | 14.63% (N=6) | 22.22% (N=8) | 20.93% (N=9) | 21.62% (N=8) |
| X2 | 0.68 | 3.33 | 4.49 | 2.97 | 1.57 |
| p-value | 0.41 | 0.19 | 0.11 | 0.23 | 0.46 |
Notes. Abbreviations: SS, Seeking Safety; WHE, Women’s Health Education; CAPS, Clinician-Administered PTSD Scale. N=141 for total sample; At baseline, n = 76 for SS and N = 65 for WHE; at posttreatment n = 41 for SS and n = 41 for WHE; at 3-month follow-up, n = 47 for SS and n = 36 for WHE; at 6-month follow-up, n = 48 for SS and 43 for WHE; At 12 month follow-up, n = 50 for SS and n = 37 for WHE. Items with an asterisk (*) indicate a significant difference between SS and WHE at the p ≤ 0.05 level.
Z-score from Mann-Whitney U nonparametric test.
The final mixed effect analysis revealed no significant treatment effects on any of the PTSD symptom cluster scores during follow-up (p > .05), nor any significant effects of baseline levels of stimulant use on PTSD symptom cluster scores during follow-up (p > .05).
Stimulant Use Outcome at Follow-Up
The generalized multinomial logistic mixed effects model revealed there was no significant main effect of treatment condition on stimulant use frequency during follow-up (χ2 (1) = 1.13, p = 0.29). Both treatment conditions demonstrated significant reductions in frequency of stimulant use at posttreatment follow-ups (see Table 2).
Changes in PTSD symptoms and its relationship to Stimulant Use at Follow-Up
There was a significant three-way interaction among baseline stimulant use, treatment group, and total PTSD symptoms improvement from baseline to each follow-up timepoint (χ2 (1) = 7.00, p < 0.01). The effect of total PTSD symptoms improvement on stimulant use outcomes during follow-up differed significantly by treatment group but only among baseline heavy stimulant users. Among participants with heavy stimulant use at baseline who were randomized to Seeking Safety, one unit of improvement on their total PTSD severity scores decreased the odds of being a heavy stimulant user at follow-up by 6.8% (t = 2.93, p < 0.01). Among participants with heavy stimulant use at baseline who were randomized to Women’s Health Education, one unit of improvement on their total PTSD severity scores increased the odds of being a heavy stimulant user at follow-up by 2.0% (t = 2.02, p < .05) (See Table 3). At baseline, 40.8% of the participants who received Seeking Safety and 47.7% of participants who received Women’s Health Education were classified as heavy stimulant users. By the 12-month follow-up, there was a 66.7% decrease in the number of Seeking Safety participants classified as heavy stimulant users compared to only a 21.4% decrease in the number of Women’s Health Education participants classified as heavy stimulant users.
Table 3.
Generalized multinomial logistic analysis examining the effect of Clinician Administered PTSD Scale (CAPS) severity score change from baseline to each follow-up timepoint on the number of days of stimulant use during follow-up by treatment group (N=141).
| (A) included Total CAPS scores | (B) included CAPS cluster scores | |||
|---|---|---|---|---|
|
| ||||
| AOR | 95% CI | AOR | 95% CI | |
| Seeking Safety | ||||
| Total PTSD Severity Change x Light Users | 0.98 | 0.94–1.01 | ||
| Total PTSD Severity Change x Heavy Users | 0.93** | 0.89–0.98 | ||
| Hyperarousal Cluster Change x Light Users | 1.01 | 0.94–1.09 | ||
| Hyperarousal Cluster Change x Heavy Users | 0.87*** | 0.80–0.94 | ||
|
| ||||
| Women’s Health Education | ||||
| Total PTSD Severity Change x Light Users | 0.95** | 0.92–0.99 | ||
| Total PTSD Severity Change x Heavy Users | 1.02* | 1.00–1.04 | ||
| Hyperarousal Cluster Change x Light Users | 0.93 | 0.84–1.02 | ||
| Hyperarousal Cluster Change x Heavy Users | 1.07* | 1.01–1.14 | ||
| Total Sample | ||||
| Re-experiencing Cluster Change | 1.00 | 0.96–1.05 | ||
| Avoidance/Numbing Cluster Change | 0.96* | 0.92–1.00 | ||
Note. AOR = Adjusted Odds Ratio. CI = Confidence Interval. Both models adjusted by site, age, race/ethnicity, education, marital status, and all four follow-up timepoints.
p < 0.05,
p < 0.01,
p < 0.001
In the model that included the three PTSD symptom clusters, there was a significant association between improvement on the avoidance/emotional numbing cluster scores and stimulant use. For the total sample, one unit of improvement on the avoidance/emotional numbing cluster scores decreased the odds of being a heavy stimulant user by 4.0% (χ2 (1) = 4.88, p = 0.03) from baseline through follow-up. There was also a significant three-way interaction among baseline level of stimulant use, treatment group, and hyperarousal cluster scores (χ2 (1) = 10.8, p < 0.001). Among participants with heavy stimulant use at baseline and who were randomized to Seeking Safety, one unit of improvement on their hyperarousal cluster scores decreased the odds of being a heavy stimulant user at follow-up by 13.4 % (t = 3.35, p < 0.001). Among participants with heavy stimulant use at baseline and who were in the WHE group, one unit of improvement on their hyperarousal cluster scores increased the odds of being a heavy stimulant user at follow-up by 7.3 % (t = 2.13, p < .05).
Conclusions and Scientific Significance
Results indicated that heavy stimulants users had significantly greater PTSD symptoms at baseline compared to light stimulant users. All stimulant users, however, benefited from both interventions and showed significant reductions in their PTSD symptoms and stimulant use posttreatment. In support of our hypothesis, improvement in total PTSD severity, after receiving treatment, was related to a reduction in the odds of heavy stimulant use at follow-up but only among heavy baseline stimulant users who received the Seeking Safety treatment. These findings are consistent with the growing body of research indicating that when individuals achieve relief from PTSD symptoms, they then are able to reduce substance use.9–12 And, findings are in line with examinations of psychiatric severity and treatment outcomes showing that for those with more severe psychiatric conditions, specific and tailored integrated treatments are more effective than general approaches.24 Seeking Safety, an integrated treatment, provides psychoeducation around the links between PTSD and substance abuse and teaches specific coping strategies to deal with difficulties related to both issues. Individuals who were heavy stimulant users at baseline received greater benefit from exploring the interrelationship between PTSD and substance use compared to those who were heavy baseline stimulant users and only received general health information.
There was a small but significant increase in the odds of heavy stimulant use at follow-up among heavy baseline stimulant users who received the Women’s Health Education intervention and showed improvement in their total PTSD severity. The intervention’s lack of focus on substance use coping strategies may have been a disadvantage for this subgroup. Among heavy substance users with co-occurring PTSD, interventions that do not incorporate skills training for substance use reduction may be contra-indicated. Nevertheless, the improvement in PTSD symptoms observed among individuals who received WHE should not be overlooked. The impact of trauma on the body is now well known.25 The material presented in the health intervention was relevant to trauma-survivors’ understanding of their body and how to think about proper self care, which may have contributed to improvements in their PTSD.
Regarding specific PTSD symptom clusters: in the total sample, improvement in the avoidance/numbing symptom cluster reduced the risk of heavy stimulant use at follow-up. This finding is consistent with research by Smith et al.14 who found a positive association between methamphetamine use and avoidance symptoms and with Najavits et al.26 who found elevated avoidance/numbing symptoms among cocaine dependent individuals with PTSD. Individuals with PTSD, particularly those who feel emotionally numb and detached from people around them, may be particularly drawn to the use of stimulants. Thus, interventions that alleviate the avoidance and emotional numbing symptoms among traumatized individuals may obviate the need to use stimulants as a therapeutic agent. There was also a significant association between improvement in the hyperarousal symptom cluster and stimulant use outcomes, but only among heavy baseline stimulant users in the Seeking Safety group. Heavy stimulant use is often associated with a worsening of hyperarousal symptoms secondary to stimulant intoxication or withdrawal.2, 26 While stimulants may be initially used to reduce certain PTSD symptoms (e.g., avoidance/emotional numbing), excessive use over time may lead to an exacerbation of other symptoms such as sleep disturbance, hypervigilance, and autonomic arousal, which in turn may lead to a cycle whereby stimulant use and PTSD symptoms mutually maintain each other.27–29 These findings suggest that for stimulant users in general, addressing the avoidance/numbing symptoms is beneficial; while among heavy stimulant users, incorporating treatment strategies that help the client cope with hyperarousal symptoms may be useful.
Several limitations should be noted. This study is primarily comprised of participants with poly-substance use and was not designed to examine women with stimulant use disorders specifically. The stimulant use variable is based on self-reported substance use and not abuse or dependence diagnosis or reported primary substance of abuse. Moreover, the stimulant use measures did not capture recent routes of use or quantity of use. Future research with women with co-occurring PTSD and stimulant use should replicate the above findings with more comprehensive measures of substance use, including time-line methodologies that can capture potential causal relationships between these two disorders.30
Nonetheless, these findings add to the growing body of literature on the functional relationship between traumatic stress responses and substance use. Findings suggest that, among heavy stimulant users, integrated treatments that lead to PTSD symptom reductions can in turn improve stimulant use outcomes. This supports treatment models that address PTSD concurrently with substance use disorder treatment.
Acknowledgments
Financial Acknowledgement:
The research reported in this article was supported by grants from the National Institute on Drug Abuse (NIDA): U10 DA13035 (Edward Nunes, PI). The Clinical Trial Identification Number is NCT00078156 (NIDA).
Footnotes
Further analyses examined an additional effect of the frequency of other substance use on treatment outcomes, but it was not significant and thus was not included in the final models.
Conflict of Interest Disclosure:
The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this paper.
References
- 1.Kessler RC, Chiu WT, Demler O, Merikangas KR, Walters EE. Prevalence, severity, and comorbidity of 12-month DSM-IV disorders in the National Comorbidity Survey Replication. Arch Gen Psychiatry. 2005;62:617–627. doi: 10.1001/archpsyc.62.6.617. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Jacobsen LK, Southwick SM, Kosten TR. Substance use disorders in patients with posttraumatic stress disorder: A review of the literature. Am J of Psychiatry. 2001;158:1184–1190. doi: 10.1176/appi.ajp.158.8.1184. [DOI] [PubMed] [Google Scholar]
- 3.Brady KT, Back SE, Coffey SF. Substance abuse and posttraumatic stress disorder. Curr Dir Psychol Sci. 2004;13:206–209. [Google Scholar]
- 4.Mills KL, Teesson M, Ross J, Peters L. Trauma, posttraumatic stress disorder, and substance use disorders: Findings from the Australian National Survey of Mental Health and Wellbeing. Am J of Psychiatry. 2006;168:651–658. doi: 10.1176/ajp.2006.163.4.652. [DOI] [PubMed] [Google Scholar]
- 5.Najavits LM, Weiss RD, Shaw SR. A clinical profile of women with PTSD and substance dependence. Psychol Addict Behav. 1999;13:98–104. [Google Scholar]
- 6.Ouimette P, Brown PJ, editors. Trauma and substance abuse: Causes, consequences, and treatment of comorbid disorders. Washington, DC: American Psychological Association; 2003. [Google Scholar]
- 7.Khantzian EJ. The self-medication hypothesis of addictive disorders: Focus on heroin and cocaine dependence. Am J of Psychiatry. 1985;142:1259–1264. doi: 10.1176/ajp.142.11.1259. [DOI] [PubMed] [Google Scholar]
- 8.Khantzian EJ. The self-medication hypothesis of substance use disorders: A reconsideration and recent applications. Harv Rev of Psychiatry. 1997;4:231–244. doi: 10.3109/10673229709030550. [DOI] [PubMed] [Google Scholar]
- 9.Chilcoat HD, Breslau N. Investigations of causal pathways between PTSD and drug use disorders. Addict Behav. 1998;23:827–840. doi: 10.1016/s0306-4603(98)00069-0. [DOI] [PubMed] [Google Scholar]
- 10.Chilcoat HD, Breslau N. Posttraumatic stress disorder and drug disorders: Testing causal pathways. Arch of Gen Psychiatry. 1998;55:913–917. doi: 10.1001/archpsyc.55.10.913. [DOI] [PubMed] [Google Scholar]
- 11.Back SE, Brady KT, Sonne SC, Verduin ML. Symptom improvement in co-occurring PTSD and alcohol dependence. J Nerv Ment Dis. 2006;194:690–696. doi: 10.1097/01.nmd.0000235794.12794.8a. [DOI] [PubMed] [Google Scholar]
- 12.Hien DA, Jiang H, Campbell ANC, et al. Do treatment improvements in PTSD severity affect substance use outcomes? A secondary analysis from a randomized clinical trial in NIDA’s clinical trials network. Am J of Psychiatry. 2010;167:95–101. doi: 10.1176/appi.ajp.2009.09091261. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.Baker A, Dawe D. Amphetamine use and co-occurring psychological problems: Review of the literature and implications for treatment. Aust Psychol. 2005;40(2):88–95. [Google Scholar]
- 14.Smith RC, Blumenthal H, Badour C, Feldner MT. An investigation of relations between crystal methamphetamine use and posttraumatic stress disorder. Addict Behav. 2010;35:625–627. doi: 10.1016/j.addbeh.2010.01.010. [DOI] [PubMed] [Google Scholar]
- 15.Hien DA, Wells EA, Jiang H, et al. Multisite randomized trial of behavioral interventions for women with co-occurring PTSD and substance use disorders. J Consult Clin Psychol. 2009;77:607–619. doi: 10.1037/a0016227. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Najavits LM. Seeking Safety: A Treatment Manual for PTSD and Substance Abuse. New York, NY: Guilford Press; 2002. [Google Scholar]
- 17.Miller S, Pagan D, Tross S. Unpublished manual. 1998. Women’s Health Education. [Google Scholar]
- 18.Gray MJ, Litz BT, Hsu JL, Lombardo TW. The psychometric properties of the Life Events Checklist. Assessment. 2004;11:330–341. doi: 10.1177/1073191104269954. [DOI] [PubMed] [Google Scholar]
- 19.Blake DD, Weathers FW, Nagy LM, et al. The development of a Clinician-Administered PTSD Scale. J Trauma Stress. 1995;8:75–90. doi: 10.1007/BF02105408. [DOI] [PubMed] [Google Scholar]
- 20.Weathers FW, Keane TM, Davidson JR. Clinician-administered PTSD scale: a review of the first ten years of research. Depress Anxiety. 2001;13:132–56. doi: 10.1002/da.1029. [DOI] [PubMed] [Google Scholar]
- 21.McLellan AT, Cacciola JS, Zanis D. The Addiction Severity Index-“Lite” (ASI-“Lite”) University of Pennsylvania/Philadelphia VA Medical Center: Center for the Studies of Addiction; 1997. [Google Scholar]
- 22.Cacciola JS, Alterman AI, McLellan AT, Lin YT, Lynch KG. Initial evidence for the reliability and validity of a “Lite” version of the Addiction Severity Index. Drug Alcohol Depend. 2007;87:297–302. doi: 10.1016/j.drugalcdep.2006.09.002. [DOI] [PubMed] [Google Scholar]
- 23.Diggle PJ, Liang KY, Zeger SL. Analysis of longitudinal data. Oxford, England: Oxford University Press; 1994. [Google Scholar]
- 24.Greenfield SF, Potter JS, Lincoln MF, Popuch RE, Kuper L, Gallop RJ. High psychiatric symptom severity is a moderator of substance abuse treatment outcomes among women in single versus mixed gender group treatment. Am J Drug Alcohol Abuse. 2008;34:594–602. doi: 10.1080/00952990802304980. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 25.van der Kolk BA, McFarlane AC, Weisaeth L. Traumatic Stress: The Effects of Overwhelming Experience on Mind, Body and Society. New York: The Guildford Press; [Google Scholar]
- 26.Najavits LM, Gastfriend DR, Barber JP, et al. Cocaine dependence with and without PTSD among subjects in the National Institute on Drug Abuse Collaborative Cocaine Treatment Study. Am J of Psychiatry. 1998;155:214–219. doi: 10.1176/ajp.155.2.214. [DOI] [PubMed] [Google Scholar]
- 27.Back SE, Brady KT. Anxiety Disorders with Comorbid Substance Use Disorders: Diagnostic and Treatment Considerations. Psychiatric Annals. 2008;38:724–729. doi: 10.3928/00485713-20081101-01. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 28.Stewart SH, Conrod PJ. Anxiety disorder and substance use disorder comorbidity: Common themes and future directions. In: Stewart H, Conrod PJ, editors. Anxiety and substance use disorders: The vicious cycle of combordity. New York, NY: Springer; 2008. pp. 239–257. [Google Scholar]
- 29.Reynolds EK, Tull MT, Shalev I, Lejuez CW. Resolving treatment complications associated with comorbid anxiety and substance use disorders. In: Otto MW, Hoffman SG, editors. Avoiding treatment failures in the anxiety disorders. Vol. 2010. New York: Springer; 2010. pp. 271–290. [Google Scholar]
- 30.Ouimette P, Read JP, Wade M, Tirone V. Modeling associations between posttraumatic stress symptoms and substance use. Addict Behav. 2010;35:64–67. doi: 10.1016/j.addbeh.2009.08.009. [DOI] [PMC free article] [PubMed] [Google Scholar]