'Dual diagnosis' refers to patients with co-existing mental health and substance misuse disorders

The term 'dual diagnosis' refers to patients with co-existing mental health and substance misuse disorders. The importance of the treatment of both mental health problems and substance misuse problems in prisons is addressed by the Mental Health Policy Implementation Guide: Dual Diagnosis Good Practice Guide (DoH, 2002a). Statistics quoted here state that at least half of prisoners on remand have substance misuse problems, with 10% being classed as moderate and 40% classed as severe.

Further, of those with substance misuse problems, theco-morbidity with mental disorders is 79%. With these figures in mind,the importance of the service, delivery and treatment of prisoners presenting with co-morbid mental disorders can be clearly seen. This essay will first examine the theory of dual diagnosis and what theevidence can tell us about its nature and how the different factors interact. Then the policy guidelines for the service and delivery oftreatments will be examined. Finally the treatment options currentlybeing used will be surveyed and assessed critically.


Theories of Dual Diagnosis

It is hard to understand the policy implications, treatment methods orservice delivery standards without first having a basic knowledge of the difficulties that researchers have had in understanding what a dual diagnosis is and how it arises. This discussion is just as relevant forthose inside and outside of the criminal justice system.

At its most basic, the idea of dual diagnosis, that of the co-occurrence of mental health problems with substance misuse problems, covers a broad range of factors, the interaction of which has been analysed by Krausz (1996) as falling into four categories. Firstly, theprimary diagnosis of mental health problems is followed by secondary problems of substance misuse then leading back in a circular fashion,into further mental health problems. Secondly substance misuse is seenas the primary diagnosis and this is followed by mental health problems, which are seen as secondary. Thirdly, the mental health problems are seen concurrently with substance misuse. Finally, there is a traumatic event which results in both mental health problems, such as a personality disorder, as well as substance misuse. These four different categories represent different lines of causation that are postulated between mental health and substance misuse.

This analysis of Krausz represents one theory of how substance abusemight interact with mental health problems - but these theories have proliferated. Mueser, Drake & Bellack (1998) provide an in depth analysis of the different types of theories surrounding dual diagnoses.Mueser et al. (1998) organise their review of the theories of comorbidity into four categories. These are, firstly, common factor models, which suppose that there are common factors that cause both substance misuse and mental health problems. Secondly, there are secondary substance use disorder models - so that mental illness causes substance misuse. Thirdly, there are secondary psychiatric disorder models which essentially propose the opposite of the last category. Finally, there are bidirectional models that do not cede primacy toeither of the disorders.

Before reviewing the evidence, it is necessary to be aware of some of the limitations in this type of research. Mueser et al. (1998) are careful to explain that they do not assume that the models are mutually exclusive, in fact they hypothesise that each will explain different individuals under a variety of circumstances. There are, also, a numbe rof other difficulties with this type of research that are identified byMueser et al. (1998). They cite the work of Hambrecht and H & aumlfner (1996) who have investigated whether alcohol abuse precedes schizophrenia orthe other way around. In their study they found that, in general, it was the alcohol abuse that came first, although actually this came after the first symptoms of schizophrenia were noticeable. Needless t osay, this is a very confusing finding. A further difficulty that ismentioned by Mueser et al. (1998) is the general presumption in psychiatry that the biological basis of disorders is paramount. Psychosocial effects tend to be minimised and treated as secondary - a view that has been challenged by a significant body of research.

Looking first, then, at common factor models, Mueser et al. (1998)divide the research into genetic factors and antisocial personalitydisorder. While there is evidence of a genetic link (for exampleTsuang, Simpson & Kronfol, 1982), there is also evidence that hasnot found a link. Kendler (1985), for example, did not find adifference in the incidence of schizophrenia and alcoholism betweenmonozygotic and dizygotic twins - the importance of this being thatmonozygotic twins generally share the same environment and all the samegenes while dizygotic twins only share half their genes. Their findingsin this research tend to downplay the importance of a genetic link.There is a considerable weight of research that has looked at the linkbetween antisocial personality disorder and substance misuse, Kessler,Crum, Warner, Nelson, Schulenberg & Anthony (1997), for example,found a strong link. Mueser, Drake, Ackerson, Alterman, Miles &Noordsy (1997) also found an association between the personalitydisorder and more severe forms of substance misuse. In analysing thisconnection Mueser et al. (1998) call on a criticism that is widespreadin the personality disorders and in psychiatric diagnoses generally,that the measures used to ascertain this diagnosis are not valid andreliable. Validity in psychology refers to whether a construct actuallymeasures what it purports to measure. Part of showing a construct'svalidity involves showing that it is just measuring one thing ratherthan overlapping, in the case of antisocial personality disorder, withsimple criminality. The labelling of a person with a personalitydisorder may hide the fact that, for example, they are the victim ofcircumstance, or perhaps social and economic conditions. This becomesconflated with the idea that a person is intrinsically mentally ill.

The secondary substance use disorder models can, according to Mueser etal. (1998) be divided into psychosocial risk factor models andbiological sensitivity models. The psychosocial model is againsubdivided by Mueser et al. (1998), but the authors report the modelwith the most empirical support is the multi-factorial model. Thefactors involved include, for example, bad interpersonal skills, socialisolation, lack of structured daily activities. The second category oftheory is that of biological sensitivity. The biological sensitivity ofschizophrenic patients has certainly been shown to be greater inamphetamine use - this contributes to a 'revolving door' effect forthese patients (Haywood, Kravitz, Grossman, Cavanaugh, Davis, &Lewis, 1995). Both of these sub-groups within this group of dualdiagnosis theories has some evidence to back it up.

Secondary psychiatric disorder models which give primacy to substancemisuse have proved controversial. Perhaps this is chiefly becausealcohol is the substance most often abused and there is little evidenceof its relationship with the specific diagnoses of bipolar disorder orschizophrenia. Indeed, there is even evidence that it contributestowards covering up the onset of the condition (Bernadt & Murray,1986). Despite this, there is evidence from some studies that certaindrugs are associated with psychosis. LSD has been associated withpsychotic outbreaks (Bowers, 1972). Andréasson, Allebeck, Engstrom,andRydberg (1987) found a link between cannabis use and schizophrenia,with heavier users showing a quicker onset of symptoms. Overall,though, Mueser et al. (1998) state that it is difficult to show astrong connection across a variety of different drugs as the evidencesimply does not exist.

Finally, in Mueser et al.'s (1998) review, the authors state that thebidirectional model has not been empirically tested. Overall, while theplethora of theoretical models have some evidence bases, none of themprovide particularly strong explanations of reality. This serves tounderline the complexity of dual diagnosis.

Service and Delivery: Mental Health Policy Implementation

What emerges, then, from the theoretical perspectives is that there isa lot of confusion and a proliferation of different approaches. So, howdo public services attempting to deal with dual diagnosis? TheDepartment of Health's (2002a) Mental Health Policy ImplementationGuide: Dual Diagnosis Good Practice Guide provides policy informationabout how services should be targeted at dual diagnosis patients.Reviewing the history of how dual diagnosis patients have been treatedin the past the guide points out that there has generally been littleintegration. In the past, drug and alcohol services have remained quiteseparate from mental health agencies. This guide puts into place a newpolicy that aims to reverse this trend. Mental health services areencouraged to provide similar sorts of treatment to that alreadyprovided by drug and alcohol services. The drug and alcohol servicesare encouraged to see themselves as consultancies to other agencies,particularly mental health services, in order to provide'mainstreaming'.

Mainstreaming refers to avoiding moving patients from one service toanother as this may lead to them leaving treatment completely. In orderthat mainstreaming should be effective, this document makes a number ofpolicy recommendations. These include specialist dual diagnosisworkers, a clear definition of what dual diagnosis means, an adequatenumber of staff available in areas like community mental health teamsand early stage intervention.

It can be seen that a high level of integrated communication andworking patterns is recommended by the document, particularly inrelation to those in prison. Those in prisons are recognised by thedocument to be at greater risk. The guidelines encourage thecommunication between different agencies including the primary careteam and prisons. They also encourage establishing partnership with thecriminal justice system, partly by creating 'in-reach' programmes todeliver these services to prisoners. The document states that as forthe treatment that is recommended for these patients, there has been noresearch in the UK into what is effective, the authors therefore turnto evidence from the US which, they claim, suggests the importance ofintegrated treatment, motivational interventions and individualcounselling.

Overall, while acknowledging that prisoners are at high risk of dualdiagnosis, there is little mention of them in this document. Weaver,Renton & Stimson (1999), in anticipation of some of therecommendation of this document, make some salient criticisms. Theyblame the way in which separate services have developed for those whohave a dual diagnosis on political ideology and point out that researchevidence has had little sway. The psychosocial model on which substancemisuse services are based, as the name suggests, tend to emphasise theimportance of psychological and social causes and remedies. Incontrast, mental health service tend to be based on the medical modelwhich is normally biologically based and encourages the diagnosis ofproblems as well as the attendant implications of compulsoryincarceration within institutions. These two groups of people approachthe world in different ways and it will, Weaver et al. (1999) suggest,be difficult for them to communicate effectively with each other.

Service and Delivery: Models of Care

The Mental Health Policy Implementation document provides an overviewof aims and objectives for dual diagnosis patients, however The Modelsof Care (DoH, 2002b) takes a closer look at the way in which treatmentcan be delivered. The Models of Care (DoH, 2002b) report does notitself cover the treatment in prisons in any detail but, as the authorsclaim, it does have a general relevance. In particular, though, it doesdescribe the care pathway for prisoners as being through a prison-basedreferral scheme.

The Models of Care (DoH, 2002b) report describes the prison-basedtreatment of those with substance misuse problems. CounsellingAssessment Referral Advice and Throughcare (CARAT) services providethat treatment and support. The staff who provide this service are notmembers of the prison service and their function is to cover a numberof areas. These include the initial assessment of the prisoner,liaising with a variety of other agencies, input into different reportsthat are required for sentencing or probation and either group orindividual counselling that aims to ameliorate the misuse problem. TheCARAT services also look to the prisoner's welfare after their sentenceis complete by providing training before they leave and assessing theirrequirements for post-prison treatment. One of the most surprisingomissions of the CARAT scheme is that it excludes alcohol misuse, whichis one of the most common substance misuse disorders (O'Grady, 2001).

The publication does report on changes introduced by a new drugstrategy. This new strategy aims to introduce new interventions thatare available from arrest through to sentencing. The primary aim willbe to get drug misusers into treatment at the earliest opportunity andemphasise the importance of integrated care pathways. The guidelineslaid out in the Models of Care (DoH, 2002b) maintains that the causesof patient's problems will often be multifactorial and change overtime. These implicitly acknowledge some of the findings from the reviewof the theoretical literature. For this reason, it is important thatcare plans are updated over time to take into account the latestcircumstances of the patient.

Treatment of Dual Diagnosis

In the delivery of interventions, the integrated care pathway hasbecome the mantra of healthcare managers. This is because it is oftenseen that different services have different philosophies (as suggestedby Weaver et al., 1999), and patients should not be expected to shuttlebetween them. Drake & Mueser (2000) describe the attributes of adual diagnosis system as including the patient receiving treatment fromthe same clinicians who are trained in both substance misuse disordersand mental health disorders. There is a much greater emphasis inintegrated treatment of not immediately confronting the patient andchallenging them to become abstinent quickly. Instead the integratedapproach focuses on a gradual and long-term strategy of harm reduction.The emphasis here is on, for example, motivational interviewing whichprovides encouragement rather than chastisement. Another innovation isthe use of 12-step programmes for alcohol abuse only in those patientswho believe they can benefit from it rather than its mandatory use.Having described some of the differences, it is nevertheless clear thatthe integrated approach does share some commonalities with moretraditional parallel approaches. For example some assessments andinterventions are still the same as are psychosocial andpsychopharmacological approaches.

The Department of Health (2002) review some of the evidence onintegrated care pathways. It seems there has been mixed evidence of abeneficial effect on the mental health outcomes of dual diagnosispatients with the use of integrated care pathways. Much of the workthat has evaluated this approach has been carried out in the US.Hellerstein, Rosenthal & Milner (1995) carried out a study in theUS on schizophrenic patients who also had substance misuse disorders.This compared the integrated with non-integrated pathways and foundlittle difference between them in the outcomes measured. This researchdoes not, however, take into account all the possible factors involved.Other research, such as that reviewed by Drake & Mueser (2000), hasfound advantages. Similar findings are reported by Drake, Yovetich,Bebout, Harris & McHugo (1997) who argue that an integratedapproach is effective in providing housing stability, reduced alcoholintake compared to the parallel approach that has been in use in the USand the UK.

One important treatment factor in the integrated pathway is the use ofmotivational interviewing. This is used to try and encourage a moreco-operational approach between patient and clinician. It ishypothesised that this will help encourage patients to return tooutpatient clinics to continue their treatment. US research on this hasprovided some supportive evidence for this approach. Swanson, Pantalon& Cohen (1999) compared motivational interviewing with the standardtreatment to the standard treatment alone. They found a statisticallysignificant difference in the group that had comorbid disorders.

So far, very generalised factors of dual diagnosis have been addressed,but it should be made clear that many interventions will be heavilyreliant on the individual needs of the patient. Research studies haveshown that treatment must take into account which dual diagnosis thepatient receives. For example, a study in the UK, Barrowclough,Haddock, Tarrier, Lewis, Moring, O'Brien, Schofield & McGovern(2001), found that when measuring days of abstinence, symptoms andgeneral functioning, a combination of cognitive, motivationalinterviewing and a family intervention was more effective in dualdiagnosis for psychosis than the standard treatment. By contrast, forbipolar disorder with substance misuse, integrated group therapy wasfound to be effective by a US study (Weiss, Griffin, Greenfield,Najavits, Wyner, Soto & Hennen, 2000).

Many other different types of treatment modalities have been examined,such as in-patient versus outpatient treatment, persuasion groups,social skills training and self-help groups (Abou-Saleh, 2004), but howmuch of the available services do dual diagnosis patients use? Studiesin the US have shown higher rates than those with a single disorder(Narrow, Reiger, Rae, Manderscheid & Locke, 1993). Other morespecific studies, such as Wu, Kouzis & Leaf (1999), have foundlittle difference between alcohol misusers with other comorbid mentalhealth problems and those without the comorbid disorders. Still, theevidence shows that the use of services by dually diagnosed patients isat least as high as other comparable groups.


It can be seen from the review of the theoretical work on dualdiagnosis that the picture is extremely complicated. Causal mechanismsare hypothesised in a number of directions with a consequentproliferation of different treatment ideas. Perhaps the only conclusionthat can be drawn with confidence from this literature is that anattempt should be made to treat every patient individually. Theprevalence of dually diagnosed patients in prisons is clearly atworrying levels, however, as can be seen from the policy documentsreviewed here, there is little mention of prisons and prisoners.Generally, prisoners are mentioned in passing, and mental health andsubstance misuse services are encouraged to integrate prisons intotheir scheme, but no particular emphasis is placed on them - indeedtheir mention is surprisingly scarce. The policy directions that arerecommended in the documents reviewed here point to an increase in theuse of integrated care pathways. It seems, from reviewing the evidence,that there is some support from studies carried out in the US that thismethod of working is beneficial to the patient with a dual diagnosis.Aside from integrated pathways a number of different treatmentmodalities have been investigated with varying degrees of success. Thisis indicative of the extremely wide and variable nature of a dualdiagnosis itself. It can only be hoped that major improvements to thetreatment of prisoners with a dual diagnosis will be made in the nearfuture.


Abou-Saleh, M. T. (2004) Dual diagnosis: management within apsychosocial context. Advances in Psychiatric Treatment, 10, 352&ndash360

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Hellerstein D. J., Rosenthal, R. N., Milner, C. R. (1995) A prospectivestudy of integrated outpatient treatment for substance-abusingschizophrenic patients, American Journal on Addictions, 4(1) pp. 33&ndash42.

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