The co-existence of mental illness and psychoactive drug or other substance use problems — otherwise known as ‘comorbidity’ or ‘dual diagnosis’ — is an issue which has been on the radar of the EU drugs agency (EMCDDA) for over a decade (1). As concern around the issue grows, the EMCDDA publishes today the most comprehensive analysis of the topic to date at European level: Comorbidity of substance use and mental disorders in Europe (2).
Psychiatric comorbidity is highly prevalent among those with substance use problems; it can lead to increased risk of hospitalisation, suicide and criminal behaviour and is difficult to manage and treat. This literature review provides policymakers and practitioners working in the drugs field with a detailed and timely overview of the concept and the tools available for its assessment and diagnosis.
‘The adequate detection and treatment of comorbid mental and substance use disorders is one of the major challenges that policymakers, professionals and clinicians working in the drugs field will face in the coming years’, says EMCDDA Director Wolfgang Götz.
‘Acknowledging and responding to the reality of such disorders is an important step towards providing better care for the many people who are affected by these interlinked problems’, Götz adds.
The link between substance use and mental health problems is a complex one and interaction between the two can play out on many levels. In some cases, the psychiatric disorder may be a risk factor for substance use, while in others it is the substance use that triggers the mental health disorder. Co-existence of the two raises a number of challenges such as chronicity, poor treatment outcomes, increased morbidity and, in some cases, more criminality.
Some of the most common combinations of drug use and mental health disorders are presented in the publication, along with the corresponding clinical recommendations and response measures implemented in treatment settings across Europe. The most usual form of comorbidity is the combination of a substance use disorder with depression; while anxiety is also frequent. The use of specific substances may also be associated with a specific mental health condition (e.g. cannabis use with psychosis; opioid use with a range of conditions such as antisocial/borderline personality disorders and eating disorders).
Data on the prevalence of psychiatric comorbidity among drug users in Europe exist, but are limited and heterogeneous regarding methods and target populations. ‘It remains important to study the occurrence of psychiatric comorbidity in drug users’, says the report, ‘both to determine its magnitude and to help improve the coverage of adequate treatment’.
The report sets out the range of instruments available today to assess psychiatric comorbidity in those with substance use disorders and presents a selection of tools used for screening and diagnosis. The choice of the most appropriate instrument (or set of instruments) is based on a number of criteria such as: context; assessment objectives; time available and the expertise of the staff. Practical recommendations offered include the use of validated screening and diagnostic instruments.
Treating individuals suffering from comorbid disorders is challenging due to the complex nature of the condition. Although the issue of providing effective treatment in this area is considered important by drug and mental health professionals, there is a lack of consensus in Europe as to the most appropriate treatment setting and the most fitting pharmacological and psychosocial strategy to adopt.
The report describes a number of barriers to treatment including: the separation of mental health and drug use treatment settings in most European countries; insufficient use of combined expertise to treat the two disorders at the same time; and a lack of suitable treatment approaches, regulations and financial resources. Practical recommendations include the consideration and treatment of the two disorders simultaneously from a multi-professional perspective.
Types of treatment and how they are organised and implemented across Europe differ considerably. The report presents an overview of existing treatment options (and current gaps) for comorbid disorders in 30 European countries (28 EU Member States, Norway and Turkey) and calls for a more in-depth review of service organisation across Europe.
‘Taking into account the burden on health and legal systems, comorbid mental disorders among drug users result in high costs for society and lead to challenges not only for clinicians but also for policymakers’, says the report. It adds that one of the key challenges in the coming years will centre on: ‘where, how and for how long to treat these patients’.
The report ends with a series of recommendations including: the systematic detection and treatment of comorbid mental health disorders in those with substance use disorders; the development of future studies to improve the evidence base for care and treatment; a review of possible early interventions to identify high-risk cases; and the inclusion of comorbidity items in current reporting systems across Europe.