Dual diagnosis

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The term dual diagnosis is used to describe the comorbid condition of a person considered to be suffering from a mental illness and a substance abuse problem. There is considerable debate surrounding the appropriateness of the term being used to describe a heterogeneous group of individuals with complex needs and a varied range of problems. The concept can be used broadly, for example depression and alcoholism, or it can be restricted to specify severe mental illness (e.g. psychosis, schizophrenia) and substance misuse disorder (e.g. cannabis abuse).

[edit] Prevalence

One US study attempting to assess the prevalence of dual diagnosis found that 47% of the people they worked with, who had schizophrenia, had had a substance misuse disorder at some time in their life and that the chances of developing a substance misuse disorder was significantly higher amongst patients suffering from a psychotic illness than in the general population without a psychotic illness^[1][2]. Another study looked at the extent of substance misuse in a group of 187 chronically mentally ill patients living in the community. According to the clinician's ratings, around a third of the sample abused alcohol, street drugs, or both during the six months before evaluation ^[3].

Further UK studies have shown slightly more moderate rates of substance misuse among mentally ill individuals. One study foung that individuals suffering from schizophrenia showed just a 7% prevalence of problematic drug use in the year prior to being interviewed and 21% reported problematic use some time before that.^[4] Wright and colleagues identified individuals with psychotic illnesses who had been in contact with services in the London borough of Croydon over the previous 6 months. Cases of alcohol or substance misuse and dependence were identified through standardised interviews with clients and keyworkers. Results showed that prevalence rates of dual diagnosis were 33% for the use of any substance, 20% for alcohol misuse only and 5% for drug misuse only. A lifetime history of any illicit drug use was observed in 35% of the sample ^[5].

[edit] Diagnosis

Substance use disorders can be confused with other psychiatric disease. There are diagnoses for substance-induced mood disorders and substance-induced anxiety disorders and thus such overlap can be complicated. For this reason, the DSM-IV advises that diagnoses of primary psychiatric disorders not be made in the absence of sobriety (of duration sufficient to allow for any substance-induced symptoms to dissipate).

[edit] Treatment

It can be very difficult to find appropriate treatment opportunities for these people.^[6] Most substance-abuse centers do not accept people with serious psychiatric conditions, and many psychiatric centers do not have expertise with substance abuse.

[edit] Theories of dual diagnosis

A number of theories to explain the relationship between mental illness and substance abuse exist. Mueser et al.^[7] have identified several theories that attempt to explain the mental illness-substance misuse relationship.

[edit] Causality

The causality theory suggests that certain types of substance abuse may causally lead to mental illness. Though causality in epidemiological studies can be difficult to establish, some evidence supporting a causal link between use of cannabis and later development of psychosis such as schizophrenia exist.^[8]

[edit] Self medication theory

The self medication theory suggests that people with severe mental illnesses misuse substances in order to relieve a specific set of symptoms and counter the negative side-effects of antipsychotic medication^[9]. Khantizan proposes that substances are not randomly chosen, but are specifically selected for their effects. For example, using stimulants such as nicotine or amphetamines can be used to combat the sedation that can be caused by higher doses of certain types of (usually typical) antipsychotic medication. Several research studies have investigated this theory further by examining the motivations for and the effect of using alcohol and drugs among people with severe mental illness. On the whole these studies appear to find no evidence in support of the self-medication theory; individuals did not use substances to alleviate specific symptoms of their psychiatric disorder, rather they appeared to use for very similar reasons given by users in the general population.^{[citation needed]}

[edit] Alleviation of dysphoria theory

The alleviation of dysphoria theory suggests that people with severe mental illness commonly feel bad about themselves and that this makes them vulnerable to using psychoactive substances to alleviate these feelings. Despite the existence of a wide range of dysphoric feelings (anxiety, depression, boredom, and loneliness), the literature on self-reported reasons for use seems to lend support for the experience of these feelings being the primary motivator for drug and alcohol misuse^[10].

[edit] Multiple risk factor theory

Another theory is that there may be that there are risk factors that can lead to both substance abuse and mental illness. Mueser hypothesises that these may include factors such as social isolation, poverty, lack of structured daily activity, lack of adult role responsibility, living in areas with high drug availability, and association with people who already misuse drugs ^[11][12]. Other evidence suggests that traumatic life events such as sexual abuse, are associated with the development of psychiatric problems and substance abuse ^[13].

[edit] The supersensitivity theory

The supersensitivity theory^[14] proposes that certain individuals who have severe mental illness also have biological and psychological vulnerabilities, caused by genetic and early environmental life events. These interact with stressful life events and result in either a psychiatric disorder or trigger a relapse into an existing illness. The theory states that although anti-psychotic medication can reduce the vulnerability, substance abuse may increase it, causing the individual to be more likely to experience negative consequences from using relatively small amounts of substances. These individuals therefore, are “supersensitive” to the effects of certain substances and suggest that individuals with psychotic illness such as schizophrenia may be less capable of sustaining moderate substance use over time without experiencing negative symptoms. Although there are limitations in the research studies conducted in this area, namely that most have focused primarily on schizophrenia, this theory provides a good rationale as to why relatively low levels of substance misuse often result in negative consequences for individuals with severe mental illness ^[14]

[edit] References