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. Author manuscript; available in PMC: 2019 Nov 1.
Published in final edited form as: Psychol Trauma. 2017 Aug 3;10(6):662–665. doi: 10.1037/tra0000309

Treatment of Co-occurring Posttraumatic Stress Disorder and Substance Use: Does Order of Onset Influence Outcomes?

Kaitlin E Bountress 1, Christal Badour 2, Julianne Flanagan 1, Amanda K Gilmore 1, Sudie E Back 1,3
PMCID: PMC5797521  NIHMSID: NIHMS892455  PMID: 28771018

Abstract

Objective

Posttraumatic stress disorder (PTSD) and substance use disorders (SUDs) represent major public health concerns, particularly among veterans. They are associated with significant distress and impairment, and are highly comorbid. Little is known, however, about what role the temporal order of diagnostic onset may play in severity of presenting symptomatology and treatment outcomes. The aim of this study, therefore, was to examine treatment outcomes by order of onset.

Method

Participants were 46 U.S. military Veterans (91.3% male) enrolled in a larger randomized controlled trial examining the efficacy of an integrated, exposure-based treatment (Concurrent Treatment of PTSD and Substance Use Disorders Using Prolonged Exposure; COPE). Participants were grouped into two categories: 1) primary PTSD (i.e., PTSD developed before the onset of SUD) or 2) primary SUD (i.e., SUD developed before the onset of PTSD).

Results

No significant associations between order of onset and baseline symptomatology were observed. The findings revealed that participants with primary PTSD were significantly more likely than participants with primary SUD to report higher levels of PTSD symptoms at the end of treatment. However, there was no effect of order of onset on SUD outcomes.

Conclusions

The findings suggest that individuals with earlier PTSD onset are a particularly high-risk group in terms of their trauma-related symptoms. Implications for treatment of comorbid PTSD/SUD are discussed.

Keywords: PTSD/SUD comorbidity, Prolonged Exposure, Relapse Prevention, veterans, order of onset

Introduction

Posttraumatic stress disorder (PTSD) and substance use disorders (SUD) frequently co-occur (Driessen et al., 2008; Reynolds et al., 2011). Veterans incur a particularly high risk for developing PTSD and SUD in comparison to the general population (Fear et al., 2010; Pietrzak et al., 2011). Compared to individuals with either PTSD or SUD alone, individuals with comorbid PTSD/SUD display more severe symptom profiles, social and occupational impairment, and poorer treatment outcomes (Blanco et al., 2013; Stein et al., 2017).

The temporal order of diagnostic onset may impact both symptom presentation and treatment outcomes. With regards to symptom presentation, several studies have reported differences in demographics, comorbid diagnoses, and trauma history based on order of onset (Brady et al., 1998; McLean, Su, & Foa, 2014). However, the findings with regards to treatment outcomes are mixed. One study of individuals with PTSD and comorbid alcohol use disorders found no differences in outcomes based on order of onset (McLean et al., 2014), while an earlier study of individuals with PTSD and comorbid alcohol use disorders found that individuals with primary PTSD (i.e., the PTSD developed before the SUD) benefited more from integrated treatment (Back, Jackson, Sonne, & Brady, 2005). To date, no studies have examined order of onset in relation to treatment outcomes among veterans. More work is needed due to the high rates of PTSD/SUD among veterans and the limited and mixed findings in previous research.

The current study examined differences in clinical presentation and treatment outcomes based on PTSD/SUD order of onset among veterans participating in an integrated, evidence-based treatment for PTSD/SUD: Concurrent Treatment of PTSD and Substance Use Disorders using Prolonged Exposure (COPE; Back et al., 2014). To our knowledge, no studies to date have examined differential outcomes based on order of PTSD/SUD using COPE or with veterans. It was hypothesized that veterans with primary PTSD would benefit more from treatment due to previous literature with civilians (Back et al., 2005).

Method

Participants

Participants were 46, treatment-seeking U.S. military veterans. They were recruited via flyers in local VA and community treatment clinics, newspaper and internet advertisements (e.g., Craigslist), and clinician referral. Eligibility included veterans (1) aged 18-65 years, (2) met DSM-IV (American Psychiatric Association, 2002) criteria for current PTSD and had a total score > 50 on the Clinician-Administered PTSD Scale (CAPS; Blake et al., 1995), (3) met DSM-IV criteria for a current SUD (APA, 2002), and (4) used alcohol or drugs in the past 90 days. Exclusion criteria included: 1) enrollment in another treatment for PTSD or SUD, 2) psychiatric conditions requiring a higher level of care, and 3) severe cognitive impairment as indicated by a score of <21 on the Mini Mental Status Exam (Folstein, Folstein, & McHugh, 1975). In the larger study, participants were randomized to either COPE or Relapse Prevention. Veterans randomized to the COPE intervention were included in the current analyses.

In terms of trauma exposure, 82.6% of included participants reported that their index trauma occurred while they were serving in the military (with the remaining 17.4% reporting a civilian trauma). Almost one-third (30.4%) reported an index traumas of combat or exposure to a war zone, 10.9% reported experiencing a fire/explosion, 10.9% reported a physical assault, and an additional 10.9% reported some other stressful event as being their index trauma.

Procedure

After providing IRB-approved informed consent, participants completed a psychiatric interview and self-report assessments. COPE treatment consisted of 12 weekly, individual, 90- minute sessions (Back et al., 2014) that integrated prolonged exposure therapy for PTSD (Foa & Rothbaum, 1998) with cognitive-behavioral relapse prevention skills for SUDs (Carroll, 1998).

Measurements

PTSD symptoms

The Clinician Administered PTSD Scale for the DSM-IV (CAPS; Blake et al., 1995) assessed PTSD diagnosis and severity of symptoms.

Substance Use

The Mini International Neuropsychiatric Interview (MINI; Sheehan et al., 1998) was used to assess SUD diagnosis at baseline. The Timeline Follow-Back (TLFB; Sobell & Sobell, 1992) assesses the percent days using alcohol or drugs (e.g., cocaine, marijuana, opioids, prescription drugs, and sedatives) for the 60 days prior to baseline and then weekly throughout treatment.

Order of Onset

Within the CAPS and MINI interviews, participants indicated the age at which their diagnosis of PTSD or SUD initiated. A dummy code was created to indicate whether each individual experienced primary onset PTSD (0) or primary onset SUD (1).

Data Analytic Plan

Ordinary Least Squares (OLS) regression models were estimated using Mplus Version 7 (Muthén & Muthén,1998–2011). All continuous covariates/predictors were centered prior to analyses. Missing data on endogenous variables was estimated as a function of the observed exogenous variables under the missingness at random assumption (Shafer & Graham, 2002).

Given work finding associations between response to treatment and/or PTSD and substance misuse and age, gender, race, and baseline psychiatric symptoms, the impact of order of onset on response to treatment was examined over and above these covariates (Maguen et al., 2011; Petry & Bickel, 1999; Roberts et al., 2010). Order of onset was used as a predictor. All interactions between covariates and the predictor were initially examined with one exception: given the small number of females in the study, we did not examine interactions between gender and order of onset. Non-significant (p < .05) interactions were removed from the model.

Results

Demographics

Participants were predominantly male (91.3%) with a mean age of 40.3 years (SD=10.5). The majority were Caucasian (67.4%), followed by 30.4% African-American, and 2.2% Other. To limit parameters estimated, race was dichotomized in study models (i.e., Caucasian versus others). On average, participants reported 1.5 deployments since 9/11, and 66.7% reported serving in the recent Iraq and/or Afghanistan conflicts.

PTSD Symptoms, Substance Misuse, and Order of Onset

The mean CAPS score in this sample was 75.7 (SD=16.5) at baseline, and 26.1 (SD = 19.8) at session 12. The mean percent of days using in this sample was 0.46 (SD = 0.3) at baseline, and 0.22 (SD = 0.3) at session 12. Of included participants, 17 (37%) reported that their PTSD diagnosis onset first, and 29 (63%) reported that their SUD diagnosis onset first. Those in the primary PTSD group experienced PTSD onset at about age 24 and SUD onset at 32; those in the primary SUD group experienced SUD onset at age 24 and PTSD onset at age 31.

Correlations among Order of Onset and PTSD and SUD Symptoms

Among the zero-order correlations, there was no association between order of onset and baseline PTSD or SUD symptoms. Individuals with primary PTSD reported significantly higher PTSD symptoms than individuals with primary SUD at session 12 (r = −.42, p < .05). There was no association between order of onset and SUD severity at session 12.

Final Study Model

Final model results are presented in Table 1. Only baseline substance use predicted session 12 substance use (i.e., higher frequency of substance use at baseline was associated with higher session 12 frequency). Order of onset predicted session 12 PTSD symptoms. Specifically, those with primary PTSD reported greater PTSD symptom severity at session 12, compared to those whose SUD developed first. No covariates were associated with session 12 PTSD1.

Table 1.

Standardized Model Results (N=46)

Session 12 PTSD Symptoms Session 12 Substance Use
Predictor B SD B SD
Age −.08 .22 .07 .20
Gender −.17 .16 −.18 .15
Race .10 .20 −.32 .17
Baseline PTSD Symptoms
.12 .18 −.12 .16
Baseline Substance Use
−.17 .21 .59*** .16
SUD onset first −.43* .20 .09 .20
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Notes:

***

p <.001,

**

p <.01,

*

p <.05; Gender: 0 = males and 1=females; Race: 0 = Caucasian, 1 = African American or Other; 0 = PTSD onset first, 1 = SUD onset first.

Discussion

This study compared veterans’ PTSD and SUD symptoms at the end of an integrated treatment for co-occurring PTSD/SUD based on temporal order of diagnostic onset. The hypothesis that veterans with primary PTSD would benefit more from treatment was not supported. However, veterans with primary PTSD evidenced less reduction in PTSD symptom severity compared to veterans with primary SUD. This is in contrast to previous research examining order of onset among civilians (Back et al., 2005). It is possible that the discrepancy in findings is related to the veteran sample or to the fact that different psychosocial interventions were employed, as the previous study utilized a cognitive behavioral therapy for SUD only and the current study was an integrated therapy for both PTSD and SUD.

Nearly two-thirds of the current sample reported that the SUD developed prior to onset of PTSD. Given that the majority of participants in the current study did have SUD prior to PTSD, it is promising that PTSD symptom reductions were greatest among this subset. However, this was a surprising finding. One possible explanation could be that veterans who developed PTSD first have had PTSD longer than individuals who developed SUD first. Participants had, therefore, been experiencing trauma-related problems for a wide range of time prior to study entry. Perhaps the greater persistence of PTSD symptoms among participants whose PTSD onset preceded SUD could be explained by this group having experienced trauma at a developmentally formative time in their lives, and/or this group having had to manage these symptoms for a longer duration of time. These factors might translate into a need for a longer duration of treatment in order to achieve similar treatment outcomes. Additionally, these factors may have resulted in a more salient association between trauma symptoms and substance use behaviors. Another plausible explanation may be that individuals who developed SUD after PTSD may have initiated or escalated substance use in order to self-medicate their PTSD symptoms. Thus, these individuals may require additional, more intensive coping skills to alleviate their coping-based substance use behaviors.

With regards to substance use outcomes, order of onset was not associated with substance use at the end of treatment. This finding is consistent with prior work (McLean et al., 2014). Additionally, this finding is promising, given difficulties in treating PTSD/SUD, and suggests that no matter the onset, substance use severity decreases at a similar rate.

Several limitations of the present study should be considered. While a rigorous design and sophisticated data analytic approach were utilized, the relatively small sample size likely limited the potential power of our analyses, and ability to detect significant effects. Further, order of onset was based on self-report data, which is vulnerable to recall bias and may be difficult for some individuals to determine retrospectively. Additionally, it is possible that substance use information may be easier to recall and report on, compared to PTSD symptoms, meaning that recall bias may have differentially impacted the two data points used to create the order of onset variable. Finally, the sample is primarily Caucasian males who received the same specific intervention. Despite these limitations, the preliminary findings inform future research examining the association between order of onset and integrated PTSD/SUD treatment outcomes.

Acknowledgments

This study was supported by National Institutes of Health (NIH) grants R01DA0314, T32MH18869, K23AA023845, and K12 DA14040. These views do not necessarily reflect those of NIH.

Footnotes

There are no conflicts of interest.

1

Models were also estimated predicting PTSD symptoms and substance use at the last session each participant attended. Because the CAPS was administered at baseline, session six, and session 12, only individuals who completed at least the first six sessions were included in these additional analyses (n=37). The results of these models replicated those in the larger sub-sample. Specifically, the effect of order of onset on session 12 PTSD symptoms and baseline substance use on session 12 substance use remained significant (p<.05).

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