Dual diagnosis (also called co-occurring disorders, COD, or dual pathology) is the condition of suffering from a mental illness and a comorbid substance abuse problem. There is considerable debate surrounding the appropriateness of using a single category for 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), or a person who has a milder mental illness and a drug dependency, such as panic disorder or generalized anxiety disorder and is dependent on opioids.
Diagnosing a primary psychiatric illness in substance abusers is challenging as drug abuse itself often induces psychiatric symptoms, thus making it necessary to differentiate between substance induced and pre-existing mental illness when going into dual diagnosis treatment .
Those with co-occurring disorders needing dual diagnosis treatment face complex challenges. They have increased rates of relapse, hospitalization, homelessness, and HIV and hepatitis C infection compared to those with either mental or substance use disorders alone.
The identification of substance-induced versus independent psychiatric symptoms or disorders has important treatment implications and often constitutes a challenge in daily clinical practice in dual diagnosis treatment. Similar patterns of comorbidity and risk factors in individuals with substance induced disorder and those with independent non-substance induced psychiatric symptoms suggest that the two conditions may share underlying etiologic factors in dual diagnosis treatment.
Drug abuse, including alcohol and prescription drugs, can induce symptomatology which resembles mental illness, which can make it difficult to differentiate between substance induced psychiatric syndromes and pre-existing mental health problems in dual diagnosis treatment. More often than not psychiatric disorders among drug or alcohol abusers disappear with prolonged abstinence. Substance induced psychiatric symptoms can occur both in the intoxicated state and also during the withdrawal state. In some cases these substance induced psychiatric disorders can persist long after detoxification, such as prolonged psychosis or depression after amphetamine or cocaine abuse. Abuse of hallucinogens can trigger delusional and other psychotic phenomena long after cessation in dual diagnosis treatment of use and cannabis may trigger panic attacks during intoxication and with use it may cause a state similar to dysthymia.
Severe anxiety and depression are commonly induced by sustained alcohol abuse which in most cases abates with prolonged abstinence. Even moderate sustained use of alcohol may increase anxiety and depression levels in some individuals that need dual diagnosis treatment. In most cases these drug induced psychiatric disorders fade away with prolonged abstinence. A protracted withdrawal syndrome can also occur with psychiatric and other symptoms persisting for months after cessation of use. Among the currently prevalent medications, benzodiazepines are the most notable drug for inducing prolonged withdrawal effects with symptoms sometimes persisting for years after cessation of use inside dual diagnosis treatment.
Prospective epidemiological studies about dual diagnosis treatment do not support the hypotheses that comorbidity of substance use disorders with other psychiatric illnesses is primarily a consequence of substance abuse or dependence or that increasing comorbidity is largely attributable to increasing use of substances.
Yet emphasis is often on the effects of substances on the brain creating the impression that dual disorders are a natural consequence of these substances. However addictive drugs or exposure to gambling will not lead to addictive behaviors or drug dependence in most individuals but only in vulnerable ones, although, according to some researchers, neuroadaptation or regulation of neuronal plasticity, and molecular changes, may alter gene expression in some cases and subsequently lead to substance use disorders that necessitate dual diagnosis treatment.
Research instruments are also often insufficiently sensitive to discriminate between independent, true dual pathology, and substance-induced symptoms. Structured instruments, as Global Appraisal of Individual Needs – Short Screener-GAIN-SS and Psychiatric Research Interview for Substance and Mental Disorders for DSM-IV-PRISM, have been developed to increase the diagnostic validity. While structured instruments can help organize diagnostic information, clinicians must still make judgments on the origin of symptoms.