Dual disorders – sometimes referred to as dual diagnosis – is a term applied to describe the co-occurrence of substance-use plus mental illness. But there has been lots of confusion and inconsistency in terminology that has hampered consistent reporting of this common state of affairs. At an APA symposium on dual disorders, experts tried to bring some clarity to this poorly understood and often overlooked psychiatric diagnosis.
Too many acronyms for dual disorders mean that it is hard to interrogate the literature and understand the true prevalence of co-occurrent substance abuse and mental illness. So said Dr Shaul Lev-Ran of the Addiction Medicine Service at the Sheba Medical Center and Tel Aviv University, Israel, during an APA symposium on dual disorders.
Two for one
Dr Lev-Ran said confusion and lack of consistency in naming ‘dual disorders’ continues to plague good documentation of how often mental illness and substance abuse collide. Adding to the difficulty in defining and describing the rate of this co-occurrence of mental illness and substance abuse is the fact that one condition may beget the other, and the additional fact that in people with mental illness, there is a lifetime risk of increased substance use – which is not quite the same as concurrent substance use.
Between the cracks
Of concern, is that people with co-occurrent mental illness and substance use disorder may “fall between the cracks” when it comes to receiving optimal care, Dr Lev-Ran said.
More common than thought
Dr Lev-Ran referred to a number of reviews in recent years which have attempted to assess data from clinical samples and comorbidity studies, and reach a value for the prevalence of dual disorders. The most recent reviews looking at patients with psychiatric diagnoses, who are receiving treatment, suggest that around 50% of patients with schizophrenia may have substance use disorder, with values less amongst patients with mood disorders.
Drugs and alcohol
Current estimates suggest that among people with substance use disorder, the lifetime prevalence odds ratio for anxiety is 2.5 and for mood disorders is 4.5. However, Dr Lev-Ran said that risks for co-occurrence in a 12-month period are more informative for helping clinicians estimate whether any given patient in their care may be at risk of dual disorder. For example, 12-month estimates are that in drug use disorder patients who are seeking treatment for their substance use, 60% have comorbid mood disorders.
Coming at it from the other direction, among people with mental health issues, it is estimated that in any 12 month period, around 10% of people with MDD may be using drugs and around 20% using alcohol.
Plagued by stigma
Dr Lev-Ran said that there continues to be stigma around substance-use – another factor that potentially under-estimates the true prevalence of dual disorders. Patients may be reluctant to divulge substance use to clinicians, fearing retribution.
Turning to substance-induced mental illness, Dr Lev-Ran and other speakers in the symposium noted that it is important to distinguish between the psychotic and withdrawal effects of substances and true primary diagnosis of a co-occurrent mental disorder.
Dr Nestor Szerman of the University of Madrid, Spain, reminded the audience that nicotine dependence and gambling addiction, now a DSM 5 recognized disorder, are also commonplace in patients with mental health issues.
More to it than reward
During the symposium several speakers touched on the neurobiology of dual disorders, urging the audience to think beyond the simple concepts of activation of dopaminergic reward centres to explain addictive behaviours. Dr Szerman was keen to stress that opioid, endocannabinoid, nicotinic and glutaminergic pathways and activity play a part, as do genetics and lifetime experiences, and in his view, addiction is not simply a disorder of the brain’s reward system.
Dr Lev-Ran called for better definitions and more research into dual disorders in order to bring this psychiatric diagnosis to wider recognition.
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