Comorbidity among mood, anxiety, and alcohol disorders is common and burdensome, affecting individuals, families, and public health. A systematic and integrative review of the literature across disciplines and research methodologies was performed. Supradisciplinary approaches were applied to the review and the ensuing critical appraisal. Definitions, measurement, and estimation are controversial and inconstant. Recovery from comorbidity cannot be easily extricated from a sociocultural milieu. Methodological challenges in quantitative and qualitative research and across disciplines are many and are discussed. The evidence supporting current treatments is sparse and short-term, and modalities operating in isolation typically fail. People easily fall into the cracks between mental health and addiction services. Clinicians feel untrained and consumers bear the brunt of this: Judgmental and moralistic interactions persist and comorbidity is unrecognized in high-risk populations. Competing historical paradigms of mental illness and addiction present a barrier to progress and reductionism is an impediment to care and an obstacle to the integration and interpretation of research. What matters to consumers is challenging to quantify but worth considering: Finding employment, safe housing, and meaning are crucial to recovery. Complex social networks and peer support in recovery are important but poorly understood. The focus on modalities of limited evidence or generalizability persists in literature and practice. We need to consider different combinations of comorbidity, transitions as opposed to dichotomies of use or illness, and explore the long-term view and emic perspectives.
- mental health
- integrative review
- dual diagnosis
- critical appraisal
Comorbidity (aka dual diagnosis or co-occurring disorders) in mental health refers here to disorders of mental illness and addiction occurring together in the same individual over a lifetime. Understanding comorbidity as a challenge to public health and clinical care evolved late in the 20th century (Drake, 2000).
This supradisciplinary (Balsiger, 2004; Kötter & Balsiger, 1999) integrative review and critical appraisal examines the breadth and diversity of perspectives on a complex health issue not easily contained within disciplinary paradigms (Crawford, Crome, & Clancy, 2003; Whittemore & Knafl, 2005).
Definitions, Terminology, and Associated Issues
The term consumer is used in this review for clarity, but it is acknowledged that some prefer other terms such as client or patient. How comorbidity is defined, measured, and estimated remains controversial and inconstant, despite the adoption of consistent terminology having been identified as a useful practical step in overcoming barriers to complex and fragmented services in Australia and elsewhere (Canaway & Merkes, 2010).
Comorbidity is used as the umbrella term in this article, as it is the term most commonly encountered in the literature. What defines recovery from comorbidity cannot be easily extricated from lived experience and the meanings and priorities an individual attributes to their recovery, within their sociocultural milieu. It is more than the presence or absence of symptoms and signs. The conceptualization and composition of recovery are elusive and inconstant and definitions and descriptions of recovery in mental illness, addiction, and comorbidity are many and varied (Bradizza, Stasiewicz, & Paas, 2006; Onken, 2007). A return to an existence with purpose or meaning is a common theme (Lloyd, 2010; Onken, 2007; Ramon, 2009).
Explicit criteria and definitions of recovery are often used etically, but those with lived experience of comorbidity have rarely been asked how they define recovery (American Psychiatric Association, 2000; Staiger et al., 2011; World Health Organisation [WHO], 2006). Definitions used by clinicians can differ from researchers (Phillips, 2007).
Why This Review Is Needed
This review focuses on Australian data to some degree in providing examples and an epidemiological underpinning but extends to the international perspective wherever possible, particularly with data from the United Kingdom and the United States of America.
Comorbidity, surprisingly to some, is “expected, rather than considered an exception” (Minkoff, 2001, p. 597), especially when addiction is the initial diagnosis but also in most where it is not (Alegria et al., 2010; Canaway & Merkes, 2010; Cosci & Fava, 2011; Drake, 2007; Driessen et al., 1998; Frigola, Fonseca, Mateu, Castillo, & Torrens, 2008; Horsfall, Cleary, Hunt, & Walter, 2009; Jerrell, Hu, & Ridgely, 1994; Kay-Lambkin, Baker, & Lewin, 2004; Minkoff, 2001; Mortlock, Deane, & Crowe, 2011; Ngo, Tait, & Hulse, 2011; Xiong Lai & Qi Rong, 2009). Twelve-month estimates are the focus of much epidemiological investigation. Comorbidity estimates range from 30% to 80% across diverse study types and measures (Canaway & Merkes, 2010; Kessler, 1997; Weaver et al., 2003). These include population-based, inpatient and outpatient treatment studies, epidemiological literature reviews, investigations of comorbidity rates in treatments settings in Australia and the United Kingdom, epidemiological analysis of treatment episodes or national surveys (Australia, United States), review by the authors of Australian national data sets, and quantitative estimates based on screening or clinical assessment in treatment settings (Australian Institute of Health and Welfare [AIHW], 2011; Bradizza et al., 2006; Cosci & Fava, 2011; Howard, Stubbs, & Arcuri, 2007; Kay-Lambkin et al., 2004; Kessler, 2004a; Mortlock et al., 2011; Staiger et al., 2011; Teesson, Slade, & Mills, 2009; Xiong Lai & Qi Rong, 2009).We focus on mood and anxiety disorders in this review (due to their greater disease burden) and on alcohol, being most commonly encountered in comorbidity (and in addiction in general) and with the greatest direct and indirect impacts on health and society in most developed countries (Australian Bureau of Statistics, 2007; Australian Institute for Health and Welfare, 2009; Degenhardt, 2008; WHO, 2011; Xiong Lai & Qi Rong, 2009).
Mood and Anxiety Disorders: Scope of the Problem
The National Surveys of Mental Health and Wellbeing (NSMHWB) are telephone surveys conducted every decade in Australia, across several thousand participants, using the WHO Composite International Diagnostic Interview (CIDI) framework, and give a broad representative example of the typical distribution of mental illness and substance use in a developed country (Australian Bureau of Statistics, 2007; Kessler, 2004b). According to the 2007 Survey, 45% of adults have had (or will have) one or more mental health disorders (including substance use disorders) in their lifetime (Australian Bureau of Statistics, 2007)
In 2007, 20% of the adult population experienced a mental disorder (Australian Bureau of Statistics, 2007). Anxiety disorders were more than twice as common as affective disorders (Australian Bureau of Statistics, 2007). The population fraction with a lifetime diagnosis of mental illness has risen progressively over recent decades, especially for anxiety and mood disorders; combined, they were the second leading cause of disease burden in 2010 in Australia (Australian Institute of Health and Welfare, 2009, 2010). However, diagnostic criteria have also changed and continue to evolve, and broadening umbrellas of how we define mental illness are a contributing and contentious factor to this increase (Wakefield, Schmitz, & Baer, 2011) (Figures 1 and 2).
Recent research in New Zealand suggests that prospective measures of lifetime risk may be closer to double the risk estimated by such retrospective measures due to recall failure and underreporting (Moffitt et al., 2010).
Alcohol and Substance Use: Scope of the Problem
In Australia, alcohol use disorders occur at triple the rate of all other drug use disorders combined with 12-month and lifetime prevalence rates (Australian Bureau of Statistics, 2007; Mortlock et al., 2011). In addiction treatment settings and hospital encounters, alcohol is the number one drug of concern in more than half of encounters; this proportion is also increasing (Australian Bureau of Statistics, 2007; Mortlock et al., 2011; Xiong Lai & Qi Rong, 2009).
Comorbidity: Scope of the Problem
Comorbidity is more chronic, persistent, and disabling than mental illness or addiction alone with comparatively poor outcomes including greatly reduced life expectancy (Chang et al., 2011; Colton & Manderscheid, 2006; Cosci & Fava, 2011; Kessler, 2004a; Withers & Hirsch, 2003). Those with comorbid conditions are at higher risk of suicide (Gimelfarb, 2007; Schmidt, 2011; Withers, 2003), physical illness (communicable and noncommunicable; Batki et al., 2009; Drake & Mueser, 2000; Mueser, Drake, & Wallach, 1998; Phillips & Labrow, 2000), homelessness, becoming a perpetrator or a victim of crime (Drake & Mueser, 1996, 2000; Marshall, 1998; Mueser et al., 1998; Wright, Gournay, Glorney, & Thornicroft, 2002), and reduced workforce participation (Schmidt, 2011).
In addition, rates of relapse and rehospitalization are higher (Mueser et al., 1998; L. M. Schmidt, Hesse, & Lykke, 2011), and people with comorbidity are heavy users of emergency services and inpatient beds (Cosci & Fava, 2011; Dickey & Azeni, 1996; Drake & Mueser, 2000; Teesson et al., 2009).
The risk of addiction is 20 times greater in inpatients who have been diagnosed with a mental illness (Xiong Lai & Qi Rong, 2009). Rates are especially high in forensic psychiatric patients and inmates in general (Ogloff, Lemphers, & Dwyer, 2004). This quantitative data is, however, clouded by variable definitions of comorbidity and by variations in classification and sampling across a multitude of diagnoses (Kessler, 2004a).
The literature also indicates systematic underreporting of vulnerable populations: in the examples from the NSMHWB used earlier, there is exclusion of people not living in private dwellings, and thereby of those in hospitals, residential facilities, psychiatric hospitals or clinics, addiction treatment services, prison, the homeless, and residents of hostels. These are all sections of the population that are at increased risk of comorbidity (Australian Institute of Health and Welfare, 2010; Drake & Mueser, 1996).
Most people with posttraumatic stress disorder (PTSD), arguably more common than depression, will have an addiction during their lifetime (Australian Bureau of Statistics, 2007; Kofoed, 1993). In addition, those with PTSD-addiction comorbidity relapse quicker, tend to have more severe PTSD symptoms, and have poor outcomes (Bradizza et al., 2006; Ouimette, Wolfe, & Chrestman, 1996; Saladin, Brady, Dansky, & Kilpatrick, 1995). A history of trauma is usually evident among women with comorbidity and youths with alcohol use disorders (Fallot, 2005; Hawke, Ford, Kaminer, & Burke, 2009).
A multidisciplinary non-date-restricted University of Western Australia Supersearch (MetaLib) initially undertaken in September 2011 included the databases APA-FT, Blackwell Synergy, JSTOR, Ebsco Megafile Premier, Proquest 5000, Science Direct and Wiley Interscience, for “comorbidity” OR “co-morbidity” in title and produced 11,044 results of which the first 498, ranked by the MetaRank algorithm, were examined by abstract for relevance and reviewed in detail as appropriate.
A multidisciplinary UWA MetaLib Supersearch for “dual diagnosis” in title, for 1970-September 2011 produced 1198 articles, 214 found relevant by abstract were reviewed.
Medline search using the keywords and Boolean operators (“client” OR “consumer” OR “lived experience”) AND (“alcohol” OR “addiction” OR “co-morbidity” OR “comorbidity” OR “dual diagnosis” OR “alcoholism” OR “dependence”) AND (“mental illness” or “psychiatric illness” OR “mood disorder” OR “depressive” OR “depression” OR “anxiety” OR “anxiety disorder” OR “PTSD” OR “post-traumatic stress disorder” OR “bipolar”) returned 174 results. Relevant articles (by abstract) were examined in detail.
Relevant references identified from citations and encountered during drafting, review, and editing of the article were also included.
Etiology: Hypotheses and Models
Traditional theories of etiology in comorbidity include the direct causal (one causes the other); the indirect causal (one disorder affects a separate variable that is a causative factor in the second disorder); bidirectionality, and the theory of shared common factors (Canaway & Merkes, 2010; Kessler, 2004a; Mueser et al., 1998). Hypotheses of underlying genetic etiology have yet to demonstrate conclusive scientific evidence and are unable to be proven on grounds of statistical inference by definition (Kessler, 2004a).
Models for mental illness treat it as the primary disorder, and treatments for addiction assume that it is the primary disorder (S. Brady et al., 1996; Shulman, 1995). Historically, the medical community has tended to see addiction as a secondary problem when both are present (Shulman, 1995). Research has recently begun exploring consumer perspectives that suggest that the motivations underlying alcohol use are similar to the general population (Robert & Kim, 2000).
This desire to identify alcoholism or mental illness as a primary and secondary duality is prominent and persistent (Anthony, Myers, Corty, & James, 1994; Crawford et al., 2003). Alcohol use is biologically plausible as a potential causal factor of depression; attempts to ascertain a temporal relationship with anxiety tend to point in the opposite direction (Jane-Llopis & Matytsina, 2006). Although the hypothesis of addiction as a process of self-medication has predominated internationally for some time (Kenny, Kidd, Tuena, Jarvis, & Robertson, 2006; Kofoed, 1993), sophisticated statistical methods are yet to elucidate this “temporal priority” that is often assumed in the literature (Kessler, 2004a, p. 731).
There is growing criticism of this directional focus in research, and the area is replete with epidemiologically contradictory findings (Back, Brady, Sonne, & Verduin, 2006; Coombes & Wratten, 2007; Kofoed, 1993; Kuo, Gardner, Kendler, & Prescott, 2006; Maremmani et al., 2011; Marquenie et al., 2006; Thomas, Randall, Book, & Randall, 2008). The focus is on the quantitative analysis of specific etically hypothesized criteria and associations, with little underlying or associated qualitative or exploratory research (Boschloo et al., 2011; Horsfall et al., 2009). That neither psychology nor biology operates exclusively from the other is a well-established quantifiable phenomenon (Eisenberg, 1986).
Themes of “self-medication” do manifest, in different fashions, but reasons given by consumers in discussing their alcohol and drug use are often consistent with those given by people with addiction issues but without mental illness (Healey, Peters, Kinderman, McCracken, & Morriss, 2009).
McKeown raises the notion that, from the perspective of a consumer (within the self-medication hypothesis), it may be experienced that alcohol use is better at symptom control than prescribed psychotropic medications, in terms of direct effects on symptoms and adverse effects (McKeown, Stowell Smith, Derricott, & Mercer, 1998).
Key Issues in the Field
What Actually Matters to Consumers?
This is a question rarely asked but one with the potential to move research and recovery forward. Results can differ greatly from the priorities of clinicians: for example, residents in a social model comorbidity treatment program valued “individualised standards of therapeutic success,” and such ambiguity presents challenges in how we integrate this with quantitative research and a desire for objective benchmarks (Weinberg & Koegel, 1996, p. 284). Finding employment or returning to education are identified as crucial to recovery by clinicians and consumers both, but are weighted heavier as a priority by consumers (Karen Leigh & Ian, 2009; Laudet, Magura, Vogel, & Knight, 2000; Palmieri & Accordino, 2004; Sainfort, Becker, & Diamond, 1996).
As another example, the democratic nature of treatment in social milieu models in addiction services is valued by consumers, with scope for goals and outcomes to be personally evolved and formulated within a broader framework (Weinberg & Koegel, 1996). This is an area warranting further research, and an area difficult to quantify.
Reductionism is a key issue and potentially a barrier to care and to the integration and interpretation of research (Thylstrup & Johansen, 2009). Broader beginnings of conceptualizing comorbidity in the early 1990s have narrowed to a medical approach—despite the limited demonstrable benefit of this paradigm operating in isolation after two decades of research focusing on reductionism and positivism, in contrast to advances seen with areas of medicine more easily reduced to physiological systems (Gorski, 1994; McKeown et al., 1998). The shift in professional and lay conceptualizations of alcohol use disorders from a moral problem to a disease model in the mid-20th century (Jellinek, 1960; Watts, 1982) is an ongoing area of controversy and uncertainty.
Diagnostic inflation is a concern, through the “progressive colonisation . . . of perceived deviance,” without demonstrable gains in outcomes for people with comorbidity (McKeown et al., 1998, p. 65). The focus on pharmacological modalities and entrenched paradigms of limited evidence persists (K. T. Brady, 2005; Miller & Roache, 2009). The extent of publication and dissemination bias is only beginning to be examined (McLaren, 2009; Song et al., 2010).
Theories of a neurobiological basis are inferential (and perhaps abductive) but not experimental at their core, and the absence of biological markers remains (Drake, Osher, & Wallach, 1991; Frances & Suzette, 2001; McRae Clark et al., 2009; Redish, 2008). Limitations of such an approach include an unsupported focus on biological reductionism in the absence of evidence supporting benefit from this approach (Crawford et al., 2003); little consideration of the social and contextual construction of addiction; little evidence of individual or population prevention applicability of the approach; reliance on laboratory studies in rodents as a model for complex human behaviors and social forces; not accounting for nondependent drug-users; and the appearance of similar behavior patterns and processes occurring in everyday life in the absence of exogenous chemicals: an example of how we attempt to, with the best of intentions, solve a complex problem by inappropriately and falsely “taming” it with alluring but illusory reductionism (Belin & Everitt, 2008; Buckley, 2007; Chambers, 2008a; Conklin, 2005, p. 12; Griffiths, 2008; Hardcastle, 2008; Hart & Krauss, 2008; Neal & Wood, 2008).
The social relationships of people with comorbidity (unlike mental illness in general) have been little researched, tending also toward short-term study, but it is likely that they can be helpful or harmful in recovery (Elspeth et al., 2004; Tracy & Johnson, 2007). Half of the typical social network is using/drinking or unsupportive of recovery, but it is impossible to reduce most relationships to being only positive or negative in their impact (Tracy & Johnson, 2007). People with comorbidity have less supportive social networks than those with an addiction alone, and there is a need to better understand how social networks change over the course of recovery (Tracy & Johnson, 2007).
Comparing Methods of Treatment and Care
The evidence supporting current treatment approaches in comorbidity is limited in quantity, short-term, methodologically limited, and needing replication (Farren & McElroy, 2010; Horsfall et al., 2009; Tiet & Mausbach, 2007). Modalities operating in isolation tend to fail: multidisciplinary and integrated approaches are associated with effectiveness at 12- to 24-month follow-up in some research (Farren, 2011; Howard et al., 2007; Moggi, Brodbeck, Költzsch, Hirsbrunner, & Bachmann, 2002; Moggi, Ouimette, Finney, & Moos, 1999). Questions needing further research in integrated and other multidisciplinary approaches include comparisons of parallel versus sequential integration. An array of diverse approaches are used in practice in Australia and internationally ranging from medication to individual or group psychotherapies to therapeutic communities and peer-support programs—there is no clear evidence singling out any particular treatment approach as advantageous although all serve a role (Drake, 2007; Horsfall et al., 2009; Iovieno, Tedeschini, Bentley, Evins, & Papakostas, 2011; Kay-Lambkin et al., 2004; Tiet & Mausbach, 2007). There is little research looking at treatment approaches in particular combinations of comorbidity or beyond actively concurrent comorbidity (Tiet & Mausbach, 2007).
Little is still known about the course of comorbidity after the first years of treatment (Iovieno et al., 2011; Schmidt, 2011), no assessment of treatment satisfaction has reported data beyond 36 months, and single data-point satisfaction ratings predominate (Bradizza et al., 2006; Granholm, Anthenelli, Monteiro, Sevcik, & Stoler, 2003; Schulte, Meier, & Stirling, 2011). This approach is challenging to generalize to the nebulous and fluid variables, interactions, timeframes, sociocultural subtleties, and individualization inherent in comorbidity (Kelly, Daley, & Douaihy, 2012; Kessler, 2004a; Thylstrup & Johansen, 2009; Tracy & Johnson, 2007).
Calls for better integration of services have been occurring in the United States and internationally for 25 years (Bachmann, 1997; Cosci & Fava, 2011) with consensus among treatment providers but with a need for a stronger evidence base in support (Brooks & Penn, 2003; Mowbray et al., 1999; Tiet & Mausbach, 2007; Watkins, Hunter, Burnam, Pincus, & Nicholson, 2005). Further research is needed in this area.
Gender differences is an area of clear deficit in research and in treatment despite strong suggestions of different associations by gender and a benefit of gender-specific programs (Fallot, 2005; Farren, 2011; Kessler, 2004a).
The evidence supporting the use of psychotropic medications in isolation in comorbidity is limited; the inclusion within multidisciplinary approaches of pharmacotherapy, however, can be of benefit. Such research, however, is usually assessing short-term outcomes (Iovieno et al., 2011; Nunes & Levin, 2004; Salloum, 2005; Torrens, Fonseca, Mateu, & Farré, 2005), and symptomatology according to the disease model, occurs in narrow trial populations (Wisniewski, 2009) and is at risk of biases of interpretation, publication, or dissemination that could be better addressed (Arias & Kranzler, 2008; Book, Thomas, Randall, & Randall, 2008; Lykke, Oestrich, Austin, & Hesse, 2010; McRae Clark et al., 2009; Nunes & Levin, 2004; Song et al., 2010). Clinical trial registers, a protection against publication bias, have recently been required by journal editors, in principle, but this is not enforced (International Committee of Medical Journal Editors, 2010; McCray & Ide, 2000; Prayle, Hurley, & Smyth, 2012; Song et al., 2010; WHO, 2012).
There is uncertain evidence of the role of antidepressant therapies in alcohol and depression comorbidity, even with short-term outcomes, with many studies involving patients receiving multiple treatment modalities concomitantly (Iovieno et al., 2011; Kelly et al., 2012; Le Fauve et al., 2004; Nunes & Levin, 2004; Pettinati et al., 2010; Tiet & Mausbach, 2007; Torrens et al., 2005). Benefits to depression outcomes may be greater than alcohol-related outcomes, but these are of low impact and needing replication (Nunes & Levin, 2004; Tiet & Mausbach, 2007; Watkins et al., 2005).
People with comorbidity are often excluded from medication trials for mental illness, even when included they drop out earlier, presenting dangers of overestimating therapeutic benefit (Adams, Liu-Seifert, & Kinon, 2007; Bradizza et al., 2006; Tiet & Mausbach, 2007).
Cessation of medication is cited as a cause of relapse in medical models but other possibilities are not always considered, including withdrawal syndromes and confounders such as consumers stopping medication because of relapse or commensurate withdrawal from other treatments (Howard et al., 2007). This is an area that may benefit from qualitative research to better appreciate consumer perspectives.
The role of peer education and support is just beginning to be explored (Kenny et al., 2006). Persons with comorbidity are less likely to participate in 12-step-based peer-support programs (Powel & Kurtz, 1996).Complex social networks in recovery are poorly understood and peer support is highly valued by consumers, providing “insights that may not be available to professionals” (Lawrence-Jones, 2010, p. 124). There has been some exploration of (and support for) the helper-role and reciprocal-learning process as being key elements of successful recovery (Bogenschutz, Geppert, & George, 2006).
Relevant research in comorbidity is limited in quantity, external validity, and methodological clarity and conflicting in outcomes for and inclusiveness of people with comorbidity (Bogenschutz et al., 2006; Chappel & DuPont, 1999; Powel & Kurtz, 1996; Ward, 2011).
An avenue for exploration is comparing 12-step- and other peer-based approaches (Bogenschutz et al., 2006). One notable study found little difference in directly comparing the 12-step approach with the secular Self-Management-And-Recovery-Training (SMART) in comorbidity recovery (Brooks & Penn, 2003).
It is difficult to separate the religious and spiritual component from 12-step programs from religious models of support (religious philosophies and terminology are intrinsic to the 12-step model), when attempting to undertake comparison with alternative peer-support models (Alcoholics Anonymous World Services, Inc., 2001; Ward, 2011). The key conclusion from the current state of 12-step research appears to be the absence of any clear evidence of harm or benefit, many who succeed in 12-step programs might do as well (or better) in other peer-support scenarios, and most participants in 12-step programs also receive professional care, which is not standard in the 12-step ethos (Bill & Alcoholics Anonymous, 1939/2001; Bogenschutz & Akin, 2000; Chappel & DuPont, 1999; Galanter, 2006).
Peer support makes further sense in enabling access to treatment for those deprived of normal professional channels—the homeless, the incarcerated, culturally and linguistically diverse subsets of larger communities, and where cost, time, or distance barriers to accessing care exist (Drake et al., 1991). It is also a way of utilizing social networks and modalities of communication inaccessible to “outsiders.” (Kenny et al., 2006).
Employment and Housing
An employment role (paid or voluntary), or other meaningful engagement such as returning to education, is highly valued as a component of recovery by consumers and aids in relapse prevention (Angela, Sheila, Kristin, & Timothy, 2005; Howard et al., 2007; Karen Leigh & Ian, 2009; Laudet et al., 2000; Palmieri & Accordino, 2004; Sainfort et al., 1996; Strickler, Whitley, Becker, & Drake, 2009).
Vocational rehabilitation for people with comorbidity is an area warranting further research (Waghorn, Chant, & Jonsdottir, 2011). One recent long-term qualitative study involving first-person accounts suggests that consumers identify symptoms of illness (or the fear of these) and medication side effects as major barriers to competitive employment (Strickler et al., 2009).
Housing (and homelessness) are important and under-rated elements of recovery in comorbidity and poorly understood by clinicians (Drake & Mueser, 2000; Padgett, Gulcur, & Tsemberis, 2006; Phillips, 2007; Tsemberis, Gulcur, & Nakae, 2004). Further research in this area is needed.
Families can be a barrier to or an aid in recovery and avenues for beneficial intervention (Mueser et al., 2009). The presence of comorbidity (compared with mental illness alone) produces stronger judgmental and negative perceptions within families (Niv, Lopez, Glynn, & Mueser, 2007). The consumer experience of the roundabout of comorbidity can also be demoralizing for family members (S. Brady et al., 1996). There have been pilot attempts of family intervention models in the United States and more research is warranted (Mueser et al., 2009).
Harm Reduction or Abstinence?
Evidence suggests that an abstinence based approach is not predictive of better outcomes (Xie, Robert, Gregory, Lynn, & Anita, 2010). The conflicts between harm-reduction and abstinence approaches are about ideology, tradition, and religion, as well as academic research, and this hampers progress (Levy, 1993; Phillips, 1998; Phillips & Labrow, 2000).
Other Barriers to Care
Those with comorbidity easily fall between the cracks in mental health and addiction services: addiction service providers commonly identify the mentally unwell as unsuitable for treatment and vice versa (S. Brady et al., 1996; Canaway & Merkes, 2010; Howard et al., 2007; Kay-Lambkin et al., 2004).
Competing Models and Paradigms
The relative value placed on lived experience in the addictions field and mental health paradigms produces a fundamental philosophical and epistemological conflict among models of care. Differences in conceptualization, epistemology, and treatment philosophies remain a barrier to comorbidity consumers (Canaway & Merkes, 2010; Coombes & Wratten, 2007; Karen Leigh & Ian, 2009; L. Schmidt, 1991).
Lack of communication, division of service provision, systems that can be antagonistic or contradictory, and disparate funding structures all limit cooperation and collaboration and generate “roundabouts” in Australia and internationally (Canaway & Merkes, 2010; Cosci & Fava, 2011; Kay-Lambkin et al., 2004; Kenny et al., 2006; Keyser, Watkins, Vilamovska, & Pincus, 2008). Comorbidity goes unrecognized in high-risk populations (Antony, 2011; Canaway & Merkes, 2010) and contributes to poor outcomes (Mortlock et al., 2011; Sabrina Janine, Petra Sylvia, John, & Mike, 2010).
Knowledge, Training, and Understanding
Health care providers can have a negative attitude toward people with comorbidity and feel untrained and unable to provide help (Barry, Tudway, & Blissett, 2002; Canaway & Merkes, 2010; Coombes & Wratten, 2007). Consumers with comorbidity encounter challenges including a lack of staff knowledge, judgmental and moralistic interactions, inflexibility, poor intersectoral referral, and exclusion from services (Lawrence-Jones, 2010; Staiger et al., 2011).
Comorbidity training programs for mental health workers improve knowledge but do not shift negative judgmental attitudes (Hughes et al., 2008). Medical models are, on current evidence, of limited effectiveness in comorbidity, which exacerbates the lack of confidence in and from medical providers (Phillips, 1998).
In consumers, experiences (or fear of) persisting stigmatization promote secrecy and withdrawal behaviors, impairing socialization, vocational rehabilitation, and fellowship/peer-support aspects of recovery (Bruce, Elmer, Michael, Jo, & Larry, 1997; Howard et al., 2007).
Integrating and Interpreting Research
Diagnostic criteria change regularly, and ambiguity and uncertainty surround terminology within and between disciplines and for the general public (Chambers, 2008b; Drake & Mueser, 2000; Lyman, 2010). Inconsistent definitions impair growth of the evidence base and cooperation across disciplines (Canaway & Merkes, 2010; Mortlock et al., 2011; Teesson et al., 2009). Neither the Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev.; DSM-IV-TR; American Psychiatric Association, 2000) nor the International Classification of diseases, 10th Edition define comorbidity as a discrete entity (WHO, 2006).
Challenges in Research Approaches and Methodologies
There is a need to research alcohol disorders as separate from other drugs of addiction (Bradizza et al., 2006), but the frequency of polysubstance use complicates research attempting to focus on any single substance (Crawford et al., 2003; Marshall, 1998). A recent review of psychotherapy and psychopharmacology reinforces calls for a less reductionist approach, greater multidisciplinary synthesis, and demonstrates that treatment modalities in isolation tend to fail (Kelly et al., 2012). Collaborative and multidisciplinary solutions are beginning to be sought, and an evidence base for the best practice is urgently needed (Schulte et al., 2011; Xiong Lai & Qi Rong, 2009).
The Quantitative Approach
Methodological challenges to quantitative research into comorbidity abound: maintaining consistent study settings; sample populations and diagnostic criteria; differences in diagnostic validity between clinicians and researchers; sparse descriptions of interventions make replicability difficult; consistency and reliability of screening and questionnaire methods; the need to exclude the more severely affected or currently ill; attrition; the impact of social/cultural/legal/drug nature/definitional changes over time; gauging to what extent cultural differences have impact on international generalizability; and the conflation of abstinent ex-drinkers with abstinent never-drinkers (Crawford et al., 2003; Drake, 2007; Horsfall et al., 2009; Mueser et al., 1998; L. Schmidt, 1991; Tarrier & Sommerfield, 2003).
A research focus on externally defined and quantified variables is unable to include assessment of differences in consumer valuation of various parameters, such as the relative importance of stable income and housing to health or symptomatology (Palmieri & Accordino, 2004).
Dichotomizing mental illness into “the well or the unwell” is of questionable benefit in recovery from comorbidity; evidence suggests that in practice, screening tools tend to be used inappropriately and infrequently (Canaway & Merkes, 2010; Mortlock et al., 2011), with risk of classification and spectrum biases (Thombs et al., 2011); on these tools, studies of comorbidity typically rely (Salo et al., 2011).
Exclusions on the assumption that mental illness must be antecedent to an addiction (Pietrzak, 2011; Tarrier & Sommerfield, 2003) limit external validity and, given the worse outcomes in comorbidity, may generate a selection bias in such trials producing and overestimation of any positive outcomes (Adams et al., 2007). Retrospective studies are limited and bias is a challenge, including forward telescoping, which could produce an age of onset bias with implications on the notions of mental illness and addiction “causality pathways” (Johnson, 2005). A key limitation is the exclusion of consumers with past or present comorbidity from clinical trials exploring addiction or mental illness, despite representing the majority of those with either mental illness or addiction disorders (Adams et al., 2007; Book et al., 2008; Tarrier & Sommerfield, 2003).
The Qualitative Approach
There is a paucity of qualitative research in the field of comorbidity in general, where we might seek answers that are driven by a search for understanding, as opposed to measuring, by exploration rather than confirmation, and by accessing the vast store of knowledge and experience held by consumers as a means of informing research: the need for qualitative data collection from consumers (and their families and carers) is identified as a major deficiency in research in the field (Coombes & Wratten, 2007; Green & Thorogood, 2004; Staiger et al., 2011).
In the qualitative literature that is available, there is a focus on high severity and low prevalence conditions (Healey et al., 2009; Strickler et al., 2009; Ward, 2011; Weinberg & Koegel, 1996) and a range of methodological limitations apparent. Although the novel exploration of the views of comorbidity consumers in Australia by Staiger et al. in 2011 unveiled some key issues, this promising study unfortunately experienced the loss of two thirds of all audio data prior to transcription and is also limited to a 12-month timeframe: a short period of time in the context of comorbidity and recovery (Staiger et al., 2011).
An unclear degree of reflexivity by researchers is a common problem, with an absence of elucidation of researcher assumptions or a positioning of the researcher in the study, or to clarify the fundamental epistemological perspectives or professional roles of the interviewers (Healey et al., 2009; Staiger et al., 2011; Wadell & Skarsater, 2007). Notwithstanding debate in the literature regarding the value, methodology, and risks of member checking (Goldblatt, Karnieli-Miller, & Neumann, 2011; Julie, 2010), a lack of iterative feedback to participants is a potential flaw in research in this area and the rationale when excluding member checking is only occasionally considered (Coombes & Wratten, 2007; Staiger et al., 2011; Strickler et al., 2009; Wadell & Skarsater, 2007). As with reflexivity, this can be a conspicuous absence when not explicitly addressed by the researcher.
How Can We Move Forward?
There are a number of gaps in our understanding evident from this review. There has been little previous research investigating how comorbidity rates differ between different combinations of mental illness and addiction disorders, and addressing the distinctions and transitions between nonuse, use, light use, and disordered or dependent use would add to knowledge (Mills et al., 2009; Swendsen et al., 2010). It seems a reasonable possibility that in Australia, for instance, with its culture of near ubiquitous alcohol use, the transition from “use of alcohol” to “dependence or problematic use” may be more useful than “use” and “nonuse” as dichotomous categories.
There is some evidence of significant differences between different comorbidity combinations (notably in regard to different mental illnesses) in clinical outcomes and in regard to social, psychological, and cultural demographics (Brems, Johnson, Burns, & Kletti, 2006). We need to understand this better. There is a need to explore what underlies the high attrition rates in comorbidity treatment and a need for research looking at how organizational characteristics of service providers relate to outcomes (Sabrina Janine et al., 2010).
The minimum data set for residential and community addiction services in Australia does not require collection of any data illuminating mental health comorbidity (AIHW, 2011). Instituting collection of this data will provide opportunities for advances in research into comorbidity and improved consumer outcomes. A focus on lifetime comorbidity rather than limiting to an arbitrary 12-month period would add to knowledge and understanding; of the 45% in the general population who appear to have a lifetime episode of mental illness, most will not have had symptoms within the past 12 months (Australian Bureau of Statistics, 2007).
There is scope for significant benefit to grow from early intervention and prevention strategies targeted at those with mental illness, to protect against the development of substance disorder comorbidities, and vice versa (Teesson et al., 2009). Regardless of issues of causality or temporal course, the strong associations indicate that there is scope for targeting secondary preventive interventions after an initial diagnosis—knowing that most will develop comorbidity in their lifetime (Kessler, 2004a).
How much can we rely on our current body of evidence-based research—when our classifications and categorizations are based on consensus and debate—but not on empirical evidence and in the absence of meaning (Cosci & Fava, 2011)? To move forward productively, one suggestion is to use qualitative approaches to interpret statistical data in a new way, as a way forward in our understanding, as opposed to measurement without meaning (Thylstrup & Johansen, 2009).
A 2011 systematic review of treatment satisfaction in comorbidity consumers (limited to quantitative studies) found that integrated comorbidity treatment produced greater consumer satisfaction, notably more so than symptom severity or socioeconomic status factors—further research in the area of treatment satisfaction is explicitly needed (Fallot, McHugo, Harris, & Xie, 2011; Schulte et al., 2011). The notions surrounding Verstehen are critically important here: of understanding action and attributed meaning from the unique perspective of the individual and in regard to social meaning (Herva, 1988; Weber, Gerth, & Mills, 1946). It is clear that there is a need to understand the consumer perspective better and a need for greater awareness of how professional advice is modified (in regard to what is heard, and what is acted on) by the unique and specific individual experiences around mental illness and harmful alcohol or drug use (Healey et al., 2009). Rarely (if ever) is the question even asked: How do consumers define comorbidity? On the basis of a clinically diagnosed illness? On the basis of having sought help, professionally or from peers? On the basis of life impact, with priorities highly individual, culturally diverse, and not always agreeing with the DSM or ICD? It is a notable flaw that consumers and their families are not considered potential experts in their own conditions (Tiet & Mausbach, 2007).
In summary, this article provides, to the best of our knowledge, a unique examination and interpretation of the comorbidity of mood or anxiety disorders and alcohol problems. Recovery (whether rebuilding, reshaping, integrating or simply coping) is a complex tapestry. This serves as a call to move beyond reductionist hegemonies and the constraints of historically entrenched viewpoints. We have the opportunity to rebuild our paradigms of mental illness and addiction on an evolving foundation with, perhaps, the consumer perspective as our starting point. Put simply, we cannot find what we are not looking for, and we cannot find answers without knowing the questions to ask. It is unlikely that there are easy answers or a distilled biological solution just beyond our reach. It is possible that we are following misguided paths, leading us deeper into the jungle—we need to continue to examine this jungle from above, certainly, but we also need to learn from those who have tread the treacherous paths concealed beneath the canopy.
Declaration of Conflicting Interests The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding The author(s) received no financial support for the research and/or authorship of this article.
- © The Author(s) 2013
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Mathew Carter, MBBS, MPH (Dist.), is a PhD candidate in the School of Population Health at the University of Western Australia. He is undertaking a thesis exploring comorbidity. He has practiced medicine in Australian hospitals and primary care with varied interests including psychiatry, primary care, and vocational rehabilitation.
Colleen Fisher, BA (SocSci)Hons, PhD, is a teaching and research professor in the School of Population Health at the University of Western Australia. Apart from her main research interest of mental health and social impacts of experiencing family and domestic violence, her other research interests include psychosocial aspects of women’s reproductive health and impact of living with chronic or life limiting illness.
Mohan Isaac, MBBS, MD (Psychiatry), DPM, FRCPsych, FRANZCP, is a professor of psychiatry health in the Community, Culture and Mental Health Unit at the School of Psychiatry and Clinical Neurosciences, the University of Western Australia, and a practicing psychiatrist. His research interests include mental health services research and public health aspects of mental health, particularly in developing countries.