Assessment and diagnosis
Substance use and substance abuse disorders are complicating factors in the assessment, diagnosis and management of EDs. Research has shown that ED patients who abuse substances demonstrate worse ED symptomatology and poorer outcomes than those with EDs alone, and that the presence of an ED in SUD patients leads to greater severity of substance abuse and poorer functional outcomes [
4,
50]. Sequelae of co-morbidity include severe medical complications [
5], longer recovery time from the ED (and/or the SUD) [
6,
20,
71], poorer functional outcomes [
4,
6], more frequent and/or severe psychiatric co-morbidity [
4,
6,
71], higher rates of suicide/suicide attempts [
1,
6] and higher mortality rates [
72,
73]. Further, recent findings suggest that clinicians should be vigilant about the possibility of suicidality in individuals with BN and SUDs because their suicidality risk may be higher than that explained by the SUD alone. Assessing for the presence of suicidality and the level of risk and the temporal order of suicidality, ED and SUD is, therefore, critical [
1].
The strongest message conveyed in the current literature is the importance of screening and assessment for co-morbid SUDs and EDs in patients presenting with either disorder [
12,
74,
75]. Once a co-morbid disorder has been identified, a full medical and psychiatric evaluation is recommended, and in the case of AN, patients may need to be medically stabilized before therapeutic treatment can commence for both disorders [
8]. One of the challenges to diagnosis is that both ED and SUD patients are often treatment resistant and may experience shame and/or guilt, leading to reluctance to report ED or SUD symptoms [
8,
12,
75]. Drug and alcohol use can also have an influence on features that are more specific to the assessment of EDs, such as weight, appetite and dietary restriction, thus complicating the diagnostic process [
75]. Collateral information is therefore key when assessing patients with EDs, while the importance of a direct but non-judgmental approach during assessment is also emphasized [
12,
74].
The use of standardized screening or assessment questionnaires is advisable [
75,
76]. Such screening tools could be used for assessing risk for both disorders in primary care [
74]. Black and Wilson (1996) found the Eating Disorder Examination – Questionnaire (EDE-Q) to be a valid screening tool to identify ED symptoms amongst a clinical sample of substance abuse patients, particularly for diagnosing BN and identifying low level ED behaviours where further assessment is indicated [
77]. For a review of screening tools for the risk/presence of EDs see Grilo et al. (2002) [
76]. According to Conason et al. (2006) brief screeners for the presence of alcohol abuse/dependence designed for use in primary care settings include the CAGE questionnaire (cut down, annoyed, guilty, eye opener) and the TWEAK test (tolerance, worried, eye-opener, amnesia, cut-down) [
74,
78,
79]. Longer instruments include the Michigan Alcoholism Screening Test (MAST) and the Alcohol Dependence Scale (ADS) [
80,
81]. Conason et al. (2006) also recommend the following screening tools for the presence of other substance disorders: the Drug Abuse Screening Test (DAST); the Two Item Alcohol and Drug Screening Questions; and the Drug Screening Questionnaire (DSQ) [
74,
82‐
84].
Conason et al. (2006) have argued that interviewing is the most effective assessment technique for diagnosing co-morbid EDs and SUDs [
74]. They recommend taking a detailed substance abuse history, including current and lifetime substance use and periods of greatest severity. Such a history should also incorporate detailed information on the function and patterns of substance use. Questions should specifically explore the misuse of substances as weight loss mechanisms, for example, caffeine, tobacco, insulin, thyroid medications, stimulants or over the counter medications (laxatives, diuretics) used for metabolism restriction, caloric restriction, appetite suppression or purging [
11,
36,
37]. Similarly, the role of alcohol or psychoactive substances in emotional regulation should be explored, for example, the use of alcohol, opiates or cannabis for the relief of anxiety, depression, guilt or shame, or for emotional reward [
27]. Wolfe and Maisto (2000) highlight the importance of a behavioural assessment (including questionnaires, self-monitoring, role play and collection of collateral information) in order to explore the functional relationship between substance use patterns and ED behaviours. Precipitants, concomitant affective states and consequences of each set of behaviours should be considered as this will aid teasing out specific risk factors as well as an understanding of the mutual influence of behaviours and emotional states [
23].
While the current psychiatric nosology for EDs utilises a symptom based approach, recent research has also focused on an alternative classification system for EDs based on co-morbid psychopathology and associated features [
3]. The proposed classification systems include (i) dietary versus dietary-negative affect EDs (where the ED is characterized by either dietary restraint, negative affect or a combination of both), (ii) under-controlled versus over-controlled EDs (which considers patterns of mood disturbances, anxiety and impulsivity) and (iii) low psychopathology EDs [
3]. Such a diagnostic approach may provide a structured way of assessing risk factors, patterns and maintaining factors of substance use in ED patients.
The following section considers the management of co-morbid EDs and SUDs including an outline of different treatment modalities.
Management
Some of the pertinent questions in the treatment of co-morbid EDs and SUDs include how to ascertain the presence of a co-morbid disorder, whether to treat the disorders concurrently, and if not, which disorder to address first [
12,
76]. One difficulty is that treatment studies for EDs and SUDs often exclude patients with dual diagnoses making research evidence on effective management strategies for this population extremely scarce [
12,
85]. Nevertheless, there are a number of important considerations. Firstly, sequential treatment may lead to an increase/relapse of symptoms of one of the disorders as symptoms of the other disorder improve [
4,
8,
86]. Secondly, symptoms of the disorder not being treated may interfere with recovery from the disorder for which treatment is underway [
87,
88]. Thirdly, inadequate management of both disorders can also increase relapse rates in symptoms of one or both [
8,
86]. An additional consideration is the presence of other co-morbid psychiatric diagnoses such as anxiety and depression which may need to be simultaneously managed in these patients [
4].
Despite the paucity of treatment outcome studies, some researchers suggest that treatments which target aetiological factors common to both disorders are effective, for example addressing difficulties with emotional regulation in concurrent binge eating and substance use disorders [
89]. Woodside and Staab (2006) recommend that when there is a current SUD, patients should undergo detoxification prior to ED treatment, and where possible this should be combined with ED treatment, for example in a residential treatment facility [
90]. Overall, the literature indicates that the ED and SUD should be addressed simultaneously [
4,
76,
86]. CASA (2003) recommend programmes which include treatments focused on substance abuse and EDs specifically, as well as individually tailored combinations of personal, group and family therapy provided by a multi-disciplinary team [
8]. General treatment principles for eating disorders such as establishing a trusting, collaborative therapeutic relationship and avoiding power struggles should be followed [
91]. Several treatment modalities are considered below.
Medical stabilisation
Patients with AN with particular medical indications such as critically low BMI, blood chemistry imbalances, dehydration, irregular cardiac function and heart rate and blood pressure abnormalities, may require hospitalisation and/or nutritional rehabilitation [
92,
93]. The rate and severity of change in physiological functioning are important to consider, for example less severe but rapid changes may necessitate hospitalization [
93]. For patients with AN, weight restoration may be important prior to the commencement of psychological treatment because the effects of starvation on affect and cognition can interfere with therapy [
93].
ED patients who abuse laxatives require immediate laxative withdrawal because of the physical danger of laxative abuse, and the increased risks of mortality [
94]. Management recommendations include immediate cessation of laxative use and medication to promote bowel function if necessary, encouragement of high fibre intake and exercise, and psycho-education. Psycho-education should cover aspects relating to the physiological effects of laxative abuse, the effects of laxative withdrawal, the physiology of normal bowel functioning and cognitive distortions surrounding laxative use, including that it does not result in weight loss [
12,
94]. Alternatively, (and especially for patients with a flaccid bowel), stimulant laxatives may be replaced by osmotic laxatives such as lactulose to promote bowel function [
12,
94]. Once all laxatives have been discontinued, a programme of desensitisation to laxative use may be implemented [
94]. Colton et al. (1999) have reported a success rate of 57% short to medium term laxative abstinence in their sample following an inpatient laxative withdrawal programme [
94].
Pharmacotherapy
Research indicates that pharmacotherapy alone should not be the primary treatment for AN [
76,
95], however anti-depressants (particularly SSRIs) have been effectively used to treat both BN patients as well as patients with an alcohol use disorder with co-morbid major depression [
38,
76,
95]. Some evidence has also been found to support the use of opioid antagonists in the treatment of both EDs and AUDs [
38]. Pharmacotherapy may be indicated in combination with therapeutic interventions [
8].
Psychological treatments
Various psychological interventions have been used in the treatment of co-morbid EDs and SUDs, ranging from individual to group and family therapy. Common features across interventions include psycho-education regarding the aetiological commonalities, risks and sequelae of concurrent ED behaviours and substance abuse, dietary education and planning, cognitive challenging of eating disordered attitudes and beliefs, building of skills and coping mechanisms, addressing obstacles to improvement and the prevention of relapse [
76,
89,
96].
There is evidence for the efficacy of various forms of CBT, including self-help CBT programmes, in the treatment of EDs (particularly BN), however the efficacy of CBT in the presence of co-morbid SUD has not been examined [
8,
74,
76,
86,
95,
97‐
99]. Sinha and O’Mally (2000) and Grilo et al. (2002) nevertheless suggest that for the treatment of EDs and alcohol abuse, a CBT approach which targets both pathogenic eating behaviours as well as alcohol use is likely to be effective [
38,
76]. They identify particularly useful strategies such as self-monitoring, identification of high risk situations and coping skills to manage emotions or situations which may trigger loss of control. Often a “stepped-care” approach is recommended where patients begin with self-help CBT and if necessary proceed to guided self-help interventions or to group or individual therapy [
100].
Motivational interviewing (MI) can be used prior to CBT intervention and aims to increase the likelihood of a patient engaging with and continuing therapy by improving insight into the problem, building commitment and increasing intrinsic motivation for change [
100]. MI combined with therapist-client feedback regarding the progress of symptom improvement (compared to the norm) and difficulties with achieving target behaviours is called motivational enhancement therapy (MET), and can be used as an individual or adjunctive treatment [
100]. Dunn et al. (2006) report mixed evidence for MET in the treatment of EDs. They found that one session of MET used as an adjunct to a CBT self-help programme in a group of patients with BN or BED led to increased readiness to change bingeing behaviours, but did not lead to change in eating attitudes, frequency of bingeing and compensatory behaviours or treatment compliance [
100]. No studies have examined the efficacy of MET with co-occurring EDs and SUDs.
Dialectical behaviour therapy (DBT) has been investigated as a treatment for co-morbid EDs and SUDs [
76]. Grilo et al. (2002) suggest that DBT, even when not focusing on ED behaviour specifically, may reduce ED symptoms in patients with BN and BED, because it teaches emotional regulation strategies and coping behaviours, and these disorders have been associated with emotional and behavioural dysregulation [
76]. Courbasson et al. (2012), in a study comparing the efficacy of DBT with treatment as usual (TAU) (which consisted of a combination of motivational interviewing, CBT and relapse prevention strategies) for patients with co-morbid EDs and SUDs, reported improved retention rates for the DBT group compared with the TAU group (87% vs. 20% post-intervention and 60% vs. 20% at 3- and 6- month follow-ups) [
85]. Their results also provide preliminary positive evidence for cognitive and behavioural treatment outcomes in the DBT group, including improved ED behaviours and attitudes, reduced rate and severity of substance use, greater regulatory capacity for negative emotions and improvement in depressive symptoms. Nearly all improvements were present post-intervention and sustained at 3- and 6- month follow-up [
85]. Courbasson et al. (2011) reported similar results for the use of mindfulness-action based cognitive behavioural therapy (MACBT) (which includes teaching mindfulness and mindful eating, increasing emotional regulation skills, providing psycho-education, encouraging balanced physical activity and focusing on strengths) for a group of patients with BED and co-morbid SUDs. They describe fewer objective binge eating episodes, reductions in severity of drug addiction and improvements in disordered eating attitudes and depressive symptoms post treatment [
89].
Some researchers also report efficacy of 12 step programmes for the treatment of SUDs, especially alcohol abuse/dependence [
12,
87]. Such programmes could run concurrently and work effectively with ED treatment [
87]. Long term individual psychotherapy has also been recommended in the treatment of co-morbid EDs and SUDs, however, this is thought to be more appropriate once recovery from SUD has been maintained for a period of time. CBT type therapies are recommended during or after substance use recovery treatment [
87].
Additional treatments that are recommended for EDs include cognitive analytic therapy, interpersonal psychotherapy, focal psychodynamic therapy and family therapy (especially for adolescents) [
8,
92,
93,
95].
Inpatient vs. outpatient treatment
The 2004 NICE clinical guidelines indicate that where possible ED patients should be treated on an outpatient basis for at least 6 months, except where severe co-morbid substance abuse is likely to interfere with outpatient treatment efficacy [
95]. Indicators for hospitalisation, partial hospitalisation, residential or intensive outpatient treatment may depend on general medical and psychiatric complications (such as depression or suicidality), symptom severity and previous course of the illness [
92].
Franko et al. (2005) found that both inpatient and outpatient treatments were effective at addressing AUD in patients with an ED [
20]. Residential treatment programmes have been found to be effective in the treatment of AN and BN both post-treatment and at 3–4 year follow-up [
101,
102]. Treatment for EDs may also take place within substance abuse treatment programmes, however not all such programmes are equipped with adequate knowledge or resources [
93]. Killeen et al. (2011) found that of the addiction treatment centres in their sample that screened for the presence of EDs, 67% of centres reported that they admit low level ED patients, and 21% reported that they treat EDs [
75]. Where inpatient or residential treatment is preferred, follow-up treatment in the form of individual or group therapy, support groups or 12 step programmes is vital to preventing relapse of both disorders [
87,
93].