Dual Diagnosis: Schizophrenia and Substance Misuse

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Dual Diagnosis: Schizophrenia and Substance Misuse

        Schizophrenia is a serious mental health disorder affecting 1% of the population, but incurs a considerable cost for the health care system due to its chronic nature. It represents a significant issue to the community as the illness not only affect the patients themselves, but also their families and friends in terms of care and social support.

Schizophrenia involves many non-medical problems to the patient and his/her carers, such as prejudice and stigma by a public who is poorly educated in regards to mental illness. Some patients find themselves rejected by employers who’re either fearful, or unwilling to hire a worker who they see as a burden to them. Thus, many chronically ill patients are caught in a deteriorating social cycle, falling into homelessness, or into crime and end up in the prison system. Patients who develop depression in association with schizophrenia also risk self-harm and suicide.

All these problems are compounded in patients with a dual diagnosis, who have a second disorder, most often substance abuse. Dual diagnosis is, unfortunately, all too common among schizophrenic patients, who have a four-fold risk of drug use [1], and approximately 50% become involved in substance abuse at some point during their illness [2].

        Dual diagnosis shows a male predominance, especially in 18 to 25 year olds. Substance abuse tends to begin in the prodromal phase of schizophrenia [3], and there are very high rates even at the onset of psychosis [4].

        Many statistics show that alcohol abuse is the greatest problem faced by patients with co-morbidity, as it is cheap and readily available [1]. However, these studies often neglect tobacco use, which is probably by far the most prevalent [5].

        Other drugs used include cannabis- especially in southwestern Sydney, and particularly among adolescents, where mental illness in combination with marijuana use is the rule rather than the exception. Prescription sedatives are also common, and patients who turn up to clinics demanding a prescription are a significant problem for GP’s. Ironically, heroin and opiods is far less common in southwestern Sydney than in inner city areas, despite its reputation as Sydney’s “heroin capital”.

        There are several unproven hypotheses attempting to explain the prevalence of substance abuse among schizophrenic patients. However, the interaction of drug use and psychosis is complex, and co-morbidity is probably a result of a combination of these factors.

        The first theory is that the patient’s illness may be a drug-induced psychosis, rather than true schizophrenia [6]. Another hypothesis, the supersensitivity model, suggests that there is an underlying biological vulnerability of the patient to both schizophrenia and substance abuse disorders [7].

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        A community project, known as “The Wall”, undertaken by mental health consumers in southwestern Sydney, in conjunction with the Fairfield Alcohol and Other Drug Counseling service, allowed patients to express their own reasons for drug use. Some of these include wanting to escape the voices, the depression, the fear and the phobias brought on by schizophrenia. Other patients reported feeling bored and lonely as their old social networks broke down, and wanting a sense of belonging, even if it is with a social group whose activity is based on drug use.

In older patients, drug use may be due ...

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