Dual Disorders

Dual disability is a really big problem. It is not just a problem with intellectual disability and mental illness. It is a problem with drugs and alcohol. It is a problem with people who have sensory disability. It is certainly a problem with people who have physical disability. The treatment of people who have dual disorders is quite unsatisfactory. Many are ping-ponged back and forth between mental health services and the other relevant health services.' Rob, a social worker

In this quality of life section, comorbidity or 'dual disorder' refers to a person with schizophrenia who also experiences one or more other disorders. This can include alcohol or other drug use disorders, intellectual disability, brain injury, medical disorders and other mental disorders. An important principle when providing services for people with a serious mental illness is that an holistic approach is taken. That is, the whole person is addressed, rather than just treating the person's symptoms. This principle is particularly relevant when providing services and care for people with mental illness who have dual disorders.

Problems associated with comorbidity

Research indicates a number of complications associated with having comorbid disorders:

  • exacerbated or worsened symptoms of schizophrenia particularly in relation to comorbid substance-use disorder;
  • increased frequency of hospitalisation;
  • disruptive behaviour (mainly related to comorbid substance-use disorder) leading to an increased risk of violence, suicide and incarceration;
  • less adherence to medication (or drugs or alcohol interfering with medications); and
  • difficulty maintaining stable housing, therefore increased risk of homelessness.
    (Jeste et al. 1996; Ziedonis & George 1997; Siegfried 1998)

Furthermore, services for people with comorbid disorders are often limited because of:

  • differences between the philosophies and treatment approaches of mental health services and the services available for other disorders (For example, prior to treatment, drug and alcohol workers expect clients to express motivation to change their substance use. Conversely, mental health workers actively follow up clients to ensure their ongoing participation in treatment);
  • a lack of services, for example many detoxification and drug and alcohol rehabilitation services do not accept people with a mental illness;
  • a lack of effective referral systems; and
  • an attitude of hopelessness conveyed by service providers due to the difficulties associated with having two long-term relapsing conditions.
    (Siegfried 1998)

Serious mental illness with comorbid substance use disorder

People with a mental illness are more likely to have a substance use disorder than other people without a mental illness (NSW Health 2000). Substance use disorders involve the use or withdrawal from substance which may include alcohol, caffeine, nicotine, prescribed medications, some poisons, cannabis and other illicit substances (Oltmanns & Emery 1995). The prevalence of mental illness and comorbid substance use is common within the general population and may be increasing.

The high rate of comorbidity between mental illness and substance-use disorder has been demonstrated by a range of population studies in the United States, New Zealand, Canada and the United Kingdom (Siegfried 1998). For example, 47% of people in the United States with schizophrenia also met the criteria for lifetime substance use disorder (Kessler et al.1994). The extent of nicotine dependence among people with schizophrenia was not included in most of this research.

Australian research in this area supports the international findings. A recent study found people with psychotic disorders reported rates of smoking, alcohol dependence and drug dependence far in excess of the rates found in the general population (Jablensky et al. 1999). The authors note: 'so-called "dual diagnosis" (a primary diagnosis of a psychotic disorder and a comorbid diagnosis of a disorder due to substance use) was made in every fourth person in the sample.' (p. 3). Some Australian clinicians have estimated that 50 per cent of people with schizophrenia have a concurrent substance use disorder (McKey 1998). A 1995 study by the Central Sydney Area Health Service showed that over 50 percent of mental health consumers with schizophrenia had a history of substance misuse (Bergen et al. 1997).

NSW Health (2000) warns that the numbers of people developing comorbid mental health and substance use is on the increase.

Reasons for comorbid substance-use

Some literature suggests there may be a common cause of both schizophrenia and substance-use disorders, for example, genetic predisposition or environmental stressors (Kessler et al. 1997; Lohr & Flynn 1992; Siegfried 1998). Alternatively, each disorder may develop independently but directly, or indirectly, affect the other.

  • People with schizophrenia may use and abuse substances for the same reasons as people in the general population. For example, to experience intoxication, to escape emotional distress, or as a social activity (Addington and Duchak 1997). These motivations may be intensified for a person with schizophrenia as a result of decreased vocational, recreational and interpersonal opportunities, and due to the distress and disempowerment associated with having a mental illness (Arber 1998; Forchuk et al. 1997).
  • People with schizophrenia may use substances to 'self-medicate', that is, to relieve anxiety and depression, or medication induced side effects (Kessler et al. 1997; Forchuk et al. 1997; Siegfried 1998).
  • Recent studies have found that cannabis use may be a risk factor for later psychosis (Arseneault et al. 2002; Sheldon 2003) in adolescence may trigger an episode of schizophrenia.

Assessment for comorbid substance-use disorder

Assessment for substance use disorder in people with a mental illness needs to involve several sources of information including the individual's psychiatric and medical records, an interview with the person as well as their family, carer or case manager. Formal screening may sometimes be appropriate as it can increase the identification of substance use disorder in people with a mental illness (Appleby et al. 1997). Those who are identified as having a confirmed or suspected substance use problem need to undergo further assessment.

Strategies for the detection and assessment of substance misuse include:

  • maintaining a high 'index of suspicion';
  • exploring past history of substance misuse;
  • being aware of demographic characteristics related to substance misuse;
  • obtaining information about the type, quantity, route and pattern of substance use;
  • sing self-report screens;
  • involving case managers, other service providers, family and carers to gather relevant information;
  • using clinical rating scales for substance use;
  • using laboratory tests (e.g. urine or blood screens) where appropriate;
  • exploring the reasons for substance use; and
  • evaluating triggers for substance use (common motives, craving/withdrawal symptoms, high risk situations).

Despite the high rates of comorbidity of schizophrenia and substance use disorders, detection remains low. This could be the result of multiple factors. Clinicians may be unaware of the high rates of comorbidity and as a consequence fail to assess people with schizophrenia for substance-use problems (Appleby et al. 1997; Arber 1998). Standard drug and alcohol assessment instruments could also be inadequate for assessing comorbidity in people with schizophrenia (Drake et al. 1996b).

Another factor relating to low detection is the possibility of psychiatric bias, whereby substance use disorders are viewed as secondary to psychiatric problems and are consequently not assessed (Appleby et al. 1997). People with a mental illness may also deny, minimalise or fail to see the connection between their substance misuse and problems of adjustment (Drake et al. 1996b; Jeste 1996). It is important to address the reasons for low detection rates as the detection and assessment of the severity of the problem is critical to planning effective treatments (Siegfried 1998).

Treatment for comorbid substance-use disorder

"I have a strong view about dual disorders. Nearly every client I have seen lately has substance use problems. I think all mental health staff need drug and alcohol training. Of course there is no evidence to support this, but it is surely common sense if most clients have this problem." Stan, a psychiatrist

It is important to decide during the assessment phase whether the substance use should be treated directly, or whether it should be dealt with as secondary to the experience of mental illness. For example, in some cases the individual with mental illness may be using drugs as a direct result of a lack of recreational pursuits, or as a means of avoiding their fear of symptoms. In these cases it may be useful to tackle the social or emotional aspects of the problem first, as substance use may significantly decrease if these things are dealt with. In other circumstances, the substance use may have arisen independently of the mental illness and therefore needs to be directly targeted.

People with a mental illness who have comorbid substance use disorder can benefit from the same strategies used to address substance use disorder in general. An effective model for treating drug and alcohol misuse involves engagement, persuasion, and active treatment and relapse prevention.

Research has indicated treatment programs for people with schizophrenia and substance-use disorders are more effective if they involve:

  • a range of interventions addressing the biopsychosocial problems associated with the disorders (Arber 1998). Strategies can include: (i) self-monitoring; (ii) social skills; training, (iii) social network interventions; (iv) self-help groups; (v) substitute activities; (vi) close monitoring; and (vii) cognitive behavioral techniques to address high risk situations, cravings, motives for substance use, and persistent symptoms;
  • the recognition of the long-term nature of substance abuse and dependence and allow for this in treatment programs (Siegfried 1998);
  • motivational interventions to promote and sustain the person's participation in programs (Mercer-McFadden et al. 1997);
  • realistic, long-term goal setting (Drake et al. 1996b); and
  • in most cases, a tolerant approach to substance use rather than a confrontational, abstinence-focused approach (Siegfried 1998).

Integration of Services

''Despite the fact that people with such comorbid disorders utilise health services more than people with a single disorder, there are very few specialist services which focus on the ongoing care and management of individuals affected by both disorders' (NSW Health 2000, p9)

Research indicates that through integrating mental health and drug and alcohol services, the detection, assessment and management of this comorbidity is improved (Siegfried 1998). These 'integrated services' involve extensive collaboration between mental health and drug and alcohol workers in the provision of a range of treatment, rehabilitation and education services. If such collaboration is to take place, mental health workers must be educated and trained in drug and alcohol issues, and drug and alcohol workers must be educated and trained in mental health issues (Kirchner et al. 1998).

Thus, current services in mental health and the drug and alcohol need to be inclusive of people with dual disorders. There is little justification for developing a single specialist service for this group, as current services can be adapted to address the gaps in the system.

Mental illness and comorbid intellectual disability

Intellectual disability is characterised by below average intellectual functioning and associated impairments in adaptive functioning (APA 1994). The prevalence of psychiatric disorders in people with intellectual disability is approximately three or four times greater than in the general population (Einfeld & Tonge 1996). For example, a survey of 1063 people with lifelong intellectual disability in New Zealand identified that 25 percent of these people also had a psychiatric diagnosis (Hand & Reid 1996). Research has indicated that those with severe psychiatric disorders and intellectual disability utilise psychiatric care at a much lower rate compared to those with psychiatric disorders in the general population (Gustafsson 1997).

Intellectual disability may arise independently from the schizophrenia or both may arise from a common brain impairment/damage (APA 1994). As with all dual disorders, it is difficult to find treatment for people with comorbid intellectual disabilities and schizophrenia as services relate to one condition or the other. Treatment for comorbid schizophrenia and intellectual disability should involve strategies that address both conditions and the interaction between the two. Clearly, psychological and social treatments must be tailored to the person's level of insight and intellectual resources.

Mental illness and comorbid physical disorder

There is an increased incidence of physical disorders among people with a mental illness. This can be the result of using medications and also the result of social problems commonly associated with schizophrenia such as increased rates of homelessness.

Mental illness and comorbid personality disorder

Personality disorder may precede the onset of serious mental illness. It is unclear whether these personality disorders are an early phase of mental illness itself or whether they are actually a separate earlier disorder (APA 1994).

Schizophrenia and other mental disorders

Depression and anxiety are commonly experienced by people with schizophrenia, often as a result of the loss of self-confidence, poor quality of life and fear of symptoms associated with having schizophrenia (Treatment Protocol Project 1997). The management of depression and anxiety follows the same principles as for other people with these conditions. When depression or anxiety co-occurs with schizophrenia the interaction between the disorders should be assessed and an inclusive Individual Service Plan developed.

Several researchers have also suggested that individuals may develop a post traumatic stress reaction after a psychotic episode. McGorry et al (1991) found up to 40 per cent of people with first episode psychosis appeared to develop post traumatic symptoms in the recovery phase of their illness.

Any number of other conditions or disorders may co-occur with a mental illness, however most other diagnoses are no more common among people with mental illness than among the general population. For example, research has explored the dual diagnosis of schizophrenia and transexualism (Mellon et al. 1989), and schizophrenia and anorexia nervosa (Ferguson & Damluji 1988).


For a list of references for this quality of life section on dual disorders, click here.

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