Editors

MauriAalto

Dual Diagnosis

The term dual diagnosis denotes a condition where substance use disorder (dependence or harmful use) co-occurs with at least one other mental disorder that is not exclusively a direct effect of the substance use (intoxication and withdrawal symptoms).
Substance abuse may affect a patient's mental symptom in different ways. It may
- precipitate mental symptom
- worsen mental symptom
- alleviate mental symptom
- have no effect on mental symptom.
The relationship between the patient's different mental health symptoms and substance abuse is not necessarily always the same.
In dual diagnosis, mental symptoms will persist even when substance use has ceased for a prolonged length of time.

About 40-60% of individuals with severe mental disorder will also have a substance use disorder during their lifetime.
At any one time, about 25-35% of individuals with severe mental disorder will also have a substance use disorder.
A substance use disorder is associated with an increased risk of developing other mental disorders and vice versa; the co-occurrence of the two conditions cannot be explained by coincidence alone. This speaks in favour of an integrated treatment approach, which views both conditions as one entity.

Since substance abuse is common in the general population and in psychiatric patients, the initial assessment of all individuals with mental illness should consider the possibility of concurrent substance abuse Recognition of Alcohol and Drug Abuse.
If the patient presents with substance abuse and mental symptoms, the goal should be to verify whether or not the mental symptoms are a result of substance abuse.
A substance use disorder may also develop after mental disorder has been diagnosed. In this case, the goal is to identify an emerging substance disorder and start its treatment as early as possible. The treatment of a psychiatric patient must therefore include repeated assessments regarding substance use, even if the patient has no previous history of substance abuse Recognition of Alcohol and Drug Abuse.

The screening and recognition of a substance use disorder is carried out as in any other patient group Recognition of Alcohol and Drug Abuse.
If the screening and assessment of substance abuse is reserved only for individuals with signs suggestive of a substance use disorder, or the disorder is referred to in the medical notes, a significant proportion of substance abusers will remain undiagnosed. The patients who will remain undiagnosed are mainly those whose substance abuse is at the early stages and who would respond well to treatment.
Poor compliance or response to the treatment of mental disorder may be related to substance abuse.
When a patient presents for the first time with substance abuse and mental symptoms, it is not necessarily possible to be certain about a dual diagnosis straightaway; an adequately long follow-up period is required.
Dual diagnosis should be considered if:
- mental symptoms persists even when substance use has ceased for an adequate length of time (at least 4 weeks)
- mental symptoms emerged before substance abuse
- the substance used by the patient usually does not cause the mental symptom found in the patient.

In a dual diagnosis, substance abuse and mental symptoms should be treated as one entity.
The best treatment results are achieved, at least in the most difficult cases, when the treatment of mental disorder and substance abuse is integrated, i.e. the same personnel treat both disorders in the same setting.
A long term approach is necessary regarding the treatment of both disorders.
Only a limited amount of specific scientific data is available relating to the treatment of dual diagnosis patients. Principally the same evidence-based interventions are employed in the treatment as in patients with only one diagnosis. Brief interventions Brief Interventions for Risky Use of Alcohol as well as drug and psychosocial therapies are used to treat the substance abuse disorder Treatment of Alcohol Withdrawal Drugs Used in Alcohol Dependence Long-Term Benzodiazepine Use and Withdrawal Treatment of Drug Addicts Psychosocial Interventions for People with Both Severe Mental Illness and Substance Misuse.
Treatment is beneficial. Mental disorder and substance use disorder both have a poorer prognosis in dual diagnosis than in each individual diagnosis. This is likely to be due to more severe symptoms at the onset of treatment rather than poorer treatment response.