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Dual diagnosis

Published 7 August 2007. Updated 16 October 2009.

Intoxicants may trigger certain mental and emotional symptoms. For example, alcohol can cause significant symptoms of depression and anxiety. When use of the intoxicant is stopped, however, these symptoms generally disappear within a few weeks. In such cases the main issue is treatment of the substance abuse problem. However, “dual diagnosis” patients have a psychiatric disorder that is independent of the direct effects of their substance abuse problem. A dual diagnosis patient’s mental or emotional symptoms, such as depression or anxiety in a person with alcohol dependency, do not disappear even long after they become sober.

Dual diagnoses are common. Around 40% of people with alcohol problems have had an unrelated psychiatric disorder at some point in their lives. The figure for people with drug problems is even higher. Around 30% of people with psychiatric disorders have also had a substance abuse problem at some stage. This figure varies significantly among specific psychiatric disorders, however. For example, around half of people with schizophrenia or bipolar disorder also have a drug problem.

Treatment for dual diagnosis patients focuses on treating both the substance abuse problem and the psychiatric disorder. Intoxicants often sustain or worsen a dual diagnosis patient’s mental or emotional symptoms, and so treatment of their substance abuse problem is often prioritised. A sufficiently long period without intoxicants is necessary to enable the presence and nature of the psychiatric disorder to be determined. In addition, treatment of many psychiatric disorders is less than optimal if the substance abuse problem is not sufficiently under control. For example, heavy use of alcohol and benzodiazepines may render medication or psychotherapy ineffective for depression or anxiety. Many dual diagnosis patients’ mental or emotional symptoms are more difficult than in patients who do not have a substance abuse problem. Treatment, however, is equally effective in both situations.

The dominant models in treatment of dual diagnosis patients have been periodic and parallel treatment, each of which contains two types of treatment. In the periodic model, first one problem is treated (e.g. the substance abuse problem in a rehabilitation clinic) and when a sufficient outcome has been achieved there, treatment of the other problem commences (e.g. depression in a psychiatric polyclinic). In the parallel treatment model, on the other hand, both problems are treated at the same time, but there is a separate treatment programme for each. A newer treatment model for dual diagnosis patients is referred to as integrated treatment. There, both problems are treated within the same programme. Integrated treatment is often needed for particularly severe psychiatric disorders.

Mauri Aalto
Senior Lecturer, Consultant Psychiatrist
Järvenpään Sosiaalisairaala hospital and the National Institute for Health and Welfare (THL)



M. Aalto: Päihdehäiriö ja samanaikainen muu mielenterveyden häiriö - kaksoisdiagnoosin hoidollinen haaste. Duodecim 2007;123(11);12938.

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