Description of the condition

Post‐traumatic stress disorder (PTSD) is a relatively common and well‐recognised psychiatric disorder that occurs following a major traumatic event (NCCMH 2005). Characteristic symptoms include re‐experiencing phenomena such as nightmares and recurrent distressing thoughts of the event, avoidance and numbing of general responsiveness such as trying not to talk about or be reminded of the traumatic event, experiencing detachment and estrangement from other people, and hyperarousal symptoms including sleep disturbance, increased irritability, and hypervigilance (APA 2013).

Substance use disorder (SUD) is defined as a complex behavioural disorder characterised by preoccupation with obtaining alcohol or other drugs and a narrowing of behavioural repertoire towards excessive consumption and loss of control over consumption. It is usually also accompanied by the development of tolerance to the substances being consumed and withdrawal and impairment in social and occupational functioning (APA 2013). In diagnostic terms, SUD is characterised by maladaptive misuse of substances (such as alcohol, amphetamines, cannabis, cocaine, hallucinogens, opioids, inhalants, phencyclidine, sedatives, hypnotics, and anxiolytics), which leads to clinically significant impairment or distress (APA 2013). Impairment might include increased tolerance, excessive prolonged usage, recurrent failure to meet important responsibilities, recurrent use in situations when this is likely to be physically dangerous, inability to reduce or limit usage, and considerable time spent obtaining substances or recovering from their effects.

Comorbidity between PTSD and SUD is common (Chilcoat 2003; Ford 2007; Reynolds 2005; Schäfer 2007). Epidemiological studies show significantly increased rates of PTSD amongst individuals with SUD (for example Chilcoat 1998a; Chilcoat 1998b; Cottler 1992; Dragan 2007; Driessen 2008; Helzer 1987; Mills 2006; Najavits 1998; Reynolds 2005; Reynolds 2011; Schäfer 2010), with the prevalence of lifetime PTSD ranging from 26% to 52% and prevalence of current PTSD from 15% to 42% (Driessen 2008; Reynolds 2011; Schäfer 2007; Schäfer 2010). In the Australian National Survey of Health and Wellbeing, Mills 2006 found opiates, sedatives, and amphetamines to be the drug groups to have most frequent comorbid PTSD. SUDs have also been found to be prevalent amongst individuals with PTSD (Chilcoat 2003; Jacobsen 2001; Mills 2006). In PTSD‐diagnosed samples, prevalence rates of comorbid substance abuse range from 19% to 35% and comorbid alcohol abuse from 36% to 52% (Breslau 1992; Kessler 1995; Pietrzak 2011), with estimates being even higher in some clinical populations, such as military veterans (Jacobsen 2001; Keane 1990; Kulka 1990; McDevitt‐Murphy 2010; Ruzek 2003). In a large epidemiological study of over 34,000 individuals in a community sample in the USA, Pietrzak 2011 found that 6.4% of the sample met lifetime diagnosis for full PTSD. Comorbidity was common across the PTSD sample (some 2463 individuals), with 46.4% meeting diagnosis for any alcohol or drug use disorder, 41.8% meeting diagnosis for alcohol abuse or dependence, and 22.3% meeting diagnosis for drug use or dependence. In another large epidemiological study, Kulka 1990 found that 73% of Vietnam veterans who met the diagnosis for PTSD qualified for a lifetime diagnosis of alcohol abuse or dependence. The Australian National Survey of Health and Wellbeing found that 34.4% of those with PTSD also had an SUD, most commonly an alcohol use disorder (24.1%) (Mills 2006). A number of other subgroups have been found to have particularly high rates of comorbidity of PTSD and SUD. Such groups include women, adolescents, the homeless, prisoners, gays and lesbians, rescue workers, sex workers, and victims of domestic violence (Najavits 2006).

Individuals with both disorders have also been found to have a more severe clinical profile than those with either disorder alone, lower general functioning, poorer well‐being, and worse outcomes across a variety of measures (Schäfer 2007). Such individuals are also more likely to meet additional criteria for other psychiatric disorders, such as affective disorders, anxiety disorders, and personality disorders (Mills 2006; Schäfer 2007). For these reasons, randomised controlled trials evaluating PTSD treatment therapies routinely exclude individuals with substance misuse‐related problems (Ouimette 2003b). A number of authors have called for greater understanding of the impact of this comorbidity on treatment outcomes and research to determine which therapies are most effective in treating these comorbid conditions (for example Mills 2006; Ouimette 2003a; Ouimette 2003b; Ouimette 2003c).

Description of the intervention

There are a number of established and evidence‐based forms of psychological therapies for both PTSD and SUD (van Dam 2012). Several forms of trauma‐focused cognitive behavioural therapy (TF‐CBT) have been demonstrated to be effective in treating PTSD (Bisson 2013; Bradley 2005). Evidence‐based therapies include prolonged exposure, cognitive processing therapy, brief eclectic psychotherapy, and cognitive therapy. A common component of these trauma‐focused therapies is that they include some form of guided exposure to the traumatic memory. For example, prolonged exposure involves asking the patient to relive the trauma imaginally. This is often conducted by creating a detailed present‐tense account of exactly what happened during the traumatic event, making an audio recording of it, and asking the individual to listen to this over and over again. Other common components of TF‐CBT include in vivo exposure to feared situations and cognitive therapy focused on distorted thinking and beliefs. Variants of these TF‐CBT models have been developed for specific subgroups. For example, narrative exposure therapy was developed for use with refugees and those who have been exposed to war and violent conflict, and skills training in affective and interpersonal regulation and narrative story telling (STAIR/NST) was developed for individuals with a history of childhood trauma. Eye movement desensitisation and reprocessing (EMDR) has also been well established as an intervention for PTSD (Bisson 2013). EMDR involves the PTSD sufferer focusing on a traumatic image, thought, emotion, and a bodily sensation whilst receiving bilateral stimulation most commonly in the form of eye movements. There is also evidence for the efficacy of stress management training in the treatment of PTSD, although treatment effects have not been demonstrated to be as great as for TF‐CBT‐based interventions or EMDR (Bisson 2013). Concerns remain about the applicability of these types of treatments to complex cases (Ruscio 2006). Studies evaluating interventions for PTSD have typically excluded those individuals with certain complexities such as SUD, suicidality, serious self harm, homelessness, and serious mental illness, and a recent meta‐analysis suggests that the benefits of specific interventions are smaller for individuals with more complex clinical problems (Gerger 2014). This study also highlighted the possible benefits gained from non‐specific interventions. A key principle of treatment that is endorsed by many expert clinicians in the trauma field is that treatment for individuals with complex PTSD presentations should be phased (Herman 1992), with an emphasis on interventions aimed at promoting a sense of safety and stabilisation of symptoms through improving self management and emotional regulation prior to the onset of trauma‐focused intervention (Cloitre 2011).

Cognitive behavioural therapies are also considered to be effective for SUD (Knapp 2007; van Dam 2012). A number of interventions based on the principles of CBT or behaviour therapy have been found to be effective for those with drug and alcohol problems. These include coping‐skills training, relapse prevention, contingency management, and behavioural couples therapy. Coping‐skills training and relapse prevention approaches are aimed at strengthening adaptive coping skills and reducing the risk of relapse in high‐risk or challenging situations. Contingency management is based on principles of operant conditioning. It aims to encourage adaptive abstinence‐focused behaviours through means of positive incentives. Contingency management has been found to be effective in the treatment of cocaine and stimulant misuse (Knapp 2007), and there is some evidence of effectiveness with opioid users (Mayet 2004). Behavioural couples therapy (BCT) recognises that interpersonal and relationship factors are often associated with relapse. In common with other cognitive behavioural therapies, BCT seeks to improve behavioural self control and develop new coping skills to facilitate and maintain abstinence. It also seeks to improve general relationship functioning and partners' coping with drinking or drug use‐related situations. BCT has been found to be effective at reducing frequency of usage, reducing negative consequences of use, and increasing relationship satisfaction in a number of studies with alcohol, opiate, and poly‐substance users (Powers 2008). Other popular psychosocial models for treating addiction include motivational interviewing (MI) and 12‐step approaches. MI is a widely used intervention in many addiction services. MI is a semi‐directive method for enhancing intrinsic motivation to change by exploring and resolving ambivalence through Socratic questioning and cognitive behavioural strategies. There is some evidence for the effectiveness of MI in reducing substance use in a number of studies (Smedslund 2011). One of the most widely used intervention programmes for alcohol misuse and dependence is the 12‐step approach, originally developed by Alcoholics Anonymous. The 12‐step approach consists of a brief, structured, manual‐driven approach to facilitating recovery from alcohol abuse, intended to be implemented over 12 to 15 sessions. Some 12‐step approaches include a spiritual approach, some are led by a professional, and others are led by former alcohol dependents. In a Cochrane review of the 12‐step approach, Ferri 2006 concluded that there was no strong evidence for effectiveness in reducing alcohol dependence, although the programme remains popular.

For various reasons, individuals with PTSD and SUD comorbidity are perceived as being more difficult to treat than individuals with either condition alone (Najavits 2002a; Schäfer 2007). This comorbidity is associated with poorer recruitment and retention in treatment programmes (Foa 2010; Najavits 2002a; Schäfer 2007), poorer treatment outcomes (Berenz 2012; Najavits 2002a; Ouimette 2003a; Ouimette 2003b; Reynolds 2005; Schäfer 2007), poorer treatment adherence, and shorter periods of abstinence post‐treatment (Brown 2003). Despite high prevalence levels, adults in treatment for SUD are frequently not assessed for PTSD (Mills 2006), or offered PTSD‐based interventions (Ford 2007; Ouimette 2003b; Reynolds 2005). There is a paucity of evidence for recommendations about treatment interventions for affective or anxiety disorders that are comorbid with SUD (Watkins 2005; Wilson 2008). In practice, a wide range of pharmacological and psychological therapies are used to treat the comorbidity. A concern for many treating clinicians related to intervention with some pharmacological agents such as benzodiazepines, is that patients might abuse these agents. In recognition of the clinical challenges involved in treating individuals with comorbid PSTD and SUD, a number of specialised psychological therapy approaches have been developed over the past 15 years or so. Three different types of treatment approach are identified in the literature (Gulliver 2010; Weiss 1995a): sequential, concurrent, and integrated. In sequential approaches, one comorbidity ‐ usually substance misuse ‐ is treated first, and the other ‐ usually PTSD ‐ afterwards. One sequential model to have received some attention is 'Transcend', a partially inpatient hospital‐based model (Donovan 2001). With concurrent approaches, each condition is treated separately but simultaneously using established evidence‐based interventions for each condition (Brady 2001; Triffleman 1999). One example of a concurrent approach is concurrent treatment of PTSD and substance use disorders using prolonged exposure (COPE) (Back 2001; Mills 2007). COPE uses cognitive behavioural therapy for substance use throughout the duration of the 13 treatment sessions and prolonged exposure for PTSD from around session five (Foa 1998). Integrative approaches treat both conditions together using interventions to address both disorders at the same time. Amongst integrative models, 'Seeking Safety' has probably received the most attention, with a number of randomised and non‐randomised evaluative studies (Najavits 2002b; Najavits 2007). Seeking Safety is a skills‐based therapy that aims to develop adaptive cognitive, behavioural, and interpersonal coping. Seeking Safety can be delivered on an individual basis or via groups.

Treatment interventions for PTSD and comorbid SUD have recently become a topic for review, in Berenz 2012 and Najavits 2013, and systematic review (Torchalla 2012; van Dam 2012). These reviews suggest some positive preliminary findings in relation to integrated and trauma‐focused psychological therapies for comorbidity. Najavits 2013, Torchalla 2012, and van Dam 2012 based their conclusions on evidence from both controlled and non‐controlled trials. All of these reviews identified significant methodological limitations in the studies reviewed. Several recently published controlled trials were not included in any of these reviews.

How the intervention might work

A number of different explanations for the relationship between SUD and PTSD have been proposed (Meyer 1986; Schäfer 2007). The most widely supported explanation is that PTSD influences the development of SUD, through means such as self medication (Schäfer 2007). Other explanations include the possibility that problematic substance use increases the risk of being exposed to trauma and increases psychological vulnerability to the effects of trauma (Meyer 1986; Schäfer 2007).

psychological therapies may therefore effect change in symptoms and functioning in such individuals through a number of different mechanisms. One potential mechanism by which psychological therapies might work is the development of enhanced coping skills which may increase the ability to regulate negative emotions (Busuttil 2009), leading to increased capacity to tolerate traumatic memories and craving urges. Another potential mechanism is the processing of trauma memories (Ehlers 2000; Foa 1998) leading to a decreased need to 'self medicate'. Psychological therapies such as those based on cognitive behavioural therapy (CBT) are also likely to promote changes in thinking and belief systems underlying trauma memories, and beliefs and ideas about substance use (Ehlers 2000; Najavits 2002b). For example, such interventions may facilitate attitudinal change to substance misuse and aid increased understanding of cognitive and situational risk factors associated with patterns of drug taking or problematic drinking, particularly those associated with past trauma. Other change mechanisms might include the development and reinforcement of adaptive coping skills which support constructive coping with both conditions (Brown 2003). It is likely that different interventions will operate though different means of change.

Why it is important to do this review

A number of systematic reviews of interventions for PTSD have been published in the Cochrane Library. As already noted, Bisson 2013 (along with other reviews, for example Bradley 2005) has described fairly robust evidence for trauma‐focused CBT and EMDR as treatments for chronic PTSD, with emerging evidence for some non‐trauma‐focused CBT‐based interventions and trauma‐focused CBT‐based group interventions. Other Cochrane reviews have considered single‐session psychological ’debriefing’ to prevent PTSD (Rose 2002), multiple‐session early psychological therapies for the prevention of PTSD (Roberts 2009), early psychological therapies to treat acute traumatic stress symptoms (Roberts 2010), pharmacological treatments (Stein 2006), combined pharmacotherapy and psychological therapies for PTSD (Hetrick 2010), and psychological therapies for the treatment of PTSD in children and adolescents (Gillies 2012). Over 70 systematic reviews of interventions for SUD have been published in the Cochrane Library. Reviews of psychological therapies have considered psychosocial interventions for cocaine and psychostimulant amphetamines‐related disorders (Knapp 2007), psychosocial interventions for opiate abuse and dependence (Mayet 2004), motivational interviewing for substance abuse (Smedslund 2011), 12‐step programmes for alcohol dependence (Ferri 2006), and psychosocial interventions to reduce alcohol consumption in concurrent problem alcohol and illicit drug users (Klimas 2014).

The issue of how best to manage or plan intervention for individuals with comorbid PTSD and SUD is a challenging one for clinicians (Najavits 2002a), and there is no real consensus about best practice. Most diagnosis‐specific guidelines for PTSD and other mental health disorders are silent as to whether the specific treatment recommendation applies to co‐occurring disorders (Watkins 2005). As we have discussed, comorbidity is a frequent problem, and those individuals with comorbidity are more challenging for general mental health services, trauma specialists, and addiction services to treat (Schäfer 2007). In clinical practice, many clinicians still argue the addiction should be treated first (for example Busuttil 2009; Foa 2000; Zayfert 2007), or that abstinence is necessary before diagnosis and a management plan can be made (see Watkins 2005). The reality for many people with comorbidity is that they can frequently get passed between services with little co‐ordination of care (Najavits 2006). Watkins 2005 argues that there has been a broad shift in the literature towards more co‐ordinated treatment plans over recent years, although it is far from clear that there is strong evidence to support this shift or that it has translated into change in routine clinical practice. There is also contention about perceived high risk of adverse effects of psychological evidence‐based treatment therapies, such as eye movement desensitisation and reprocessing and prolonged exposure, with comorbid groups (see Watkins 2005). We hope this review will be able to shed some light on what evidence there is to support these different models and treatment approaches, in order to aid clinician decision making.