This page refers to the current evidence on the effectiveness of the available treatment options for dual-diagnosis patients. Information on the methodology used and the definition of terms can be found on the methodology page.
Date of last update: 12.2016 Next update: 04.2017
No interventions met the criteria for this category.
Combining CBT with antidepressants was found in a comprehensive review (EMCDDA 2015) to be effective in:
Antipsychotic (Clozapine) was found in a comprehensive review (EMCDDA 2015) to be effective in:
Integrated treatment of psychosis and substance use disorders (i.e. combining psychological and antipsychotic treatments) was found in a comprehensive review (EMCDDA 2015) to be effective in:
Dialectical behavioural therapy was found in a comprehensive review (EMCDDA 2015) to be effective in:
No interventions met the criteria for this category.
Pharmacological treatment of attention deficit hyperactivity disorder (ADHA) was found in a systematic review with meta-analysis (Cunill et al., 2015, 13 studies, N = 1271) to have no effect in:
Antidepressant and psychosocial treatments were analysed in a comprehensive review (EMCDDA 2015) which found that:
A comprehensive review (EMCDDA 2015) found that:
No interventions met the criteria for this category.
Below you can find definitions and further explanation for some of the terms used in this section of the Best practice portal. A more general glossary for the best practice portal is also available.
A type of prevention intervention which aims to they aim to modify inner qualities (personality traits such as self-esteem and self-efficacy, and motivational aspects such as the intention to use drugs).
Before-after (BA) study design
Blood alcohol level (BAL)
Interventions for which precise measures of the effects in favour of the type of intervention were found in systematic reviews of relevant studies. An intervention ranked as ‘beneficial’ is suitable for most patients/contexts. See the relevant module methodology page for further information.
Controlled before-after (CBA) study design. UCBA stands for Uncontrolled before-after study design.
Cognitive behavioral therapy is an individual based intervention occurring in three stages. Phase 1 is aimed at determining and prioritizing the patient’s problems and constructing the treatment contract. Phase 2 is aimed at increasing coping competence and reducing risky behaviors. Phase 3 focuses on relapse prevention. Each session is administered once per week over a period of 4-6 months with 60- to 90-minute sessions (Beck AT, Wright FW, Newman CF, Liese B. Cognitive Therapy of substance abuse. New York: Guilford Press, 1993).
Controlled clinical trials (CCT)
A cohort study is a type of observational study that follows a group of people (i.e. a cohort) over time. In a prospective cohort study, the cohort is formed and then followed over time. In a retrospective cohort study, data is gathered for a cohort that was formed sometime in the past.
The Confidence Interval (CI) is a measure of the precision (or uncertainty) of study results. It is the interval that most likely includes the true value of the parameter we are calculating, where 'most likely' is taken by common usage to be a 95% probability. Thus the current expression of '95 % CI'. A wide CI indicates less precise estimates of effect and vice versa.
Practical interpretation
Current population survey (CPS)
A cross-sectional study is a study employing a single point of data collection for each participant or system being studied.They are usually conducted to estimate the prevalence of the outcome of interest for a given population at a given point in time.
Interventions that gave negative results if compared with a standard intervention or no intervention, for example. See the relevant module methodology page for further information.
Additional information for prevention
For ethical reasons this category in prevention should be considered as interventions with negative and undesired (iatrogenic) effect.
Individual psychotherapy is a standard individual treatment based on counseling and motivational interviewing and focused on substance use triggers and strategies for relapse prevention. It includes elements of cognitive-behavioral therapy (CBT).
Interquartile range (IQR) - also called the midspread or middle fifty - is a measure of statistical dispersion. It is a trimmed estimator, defined as the 25% trimmed mid-range, and is the most significant basic robust measure of scale.
Intermittent time series design (ITS)
Knowledge-focused prevention intervention
A type of prevention intervention which aims to to enhance knowledge of drugs, and drug effects, and consequences.
Interventions that were shown to have limited measures of effect, that are likely to be effective but for which evidence is limited. An intervention ranked as ‘likely to be beneficial’ is suitable for most contexts/patients, with some discretion. See the relevant module methodology page for further information.
The Number Needed to Treat (NNT)indicates the number of patients that needs to be treated to obtain one respondent patient. Numerically the NNT is the reciprocal of the difference between the proportion of events in the experimental and the comparison group (absolute risk reduction). Taking into consideration that the ideal NNT would be 1 (the unreal situation in which every single patient succeeded) it is easily understood that a NNT value close to 3 or 4 would be very good.
The Adjusted Odds Ratio is a way of comparing whether the probability of a certain event is the same between two groups, yet they are calculated adjusting for or controlling for other possible contributions from other variables (tipically demographic variables) in the model. An AOR equal to 1 implies that the the event is equally probable in both groups. An AOR greater than 1 implies that the event is more likely in the first group. An AOR less than 1 implies that the event is less likely in the first group.
The Odds Ratio is a way of comparing whether the probability of a certain event is the same between two groups. Like the Relative Risk, an OR equal to 1 implies that the the event is equally probable in both groups. A OR greater than 1 implies that the event is more likely in the first group. A OR less than 1 implies that the event is less likely in the first group. In medical research, the odds ratio is commonly used for case-control studies, as odds, but not probabilities, are usually estimated. Relative risk is used in randomized controlled trials and cohort studies.
A p-value is a measure of how much evidence we have against the null hypothesis. The null hypothesis represents the hypothesis of no change or no effect. The smaller the p-value, the more evidence we have against the null hypothesis thus it is more likely that our sample result is true. Traditionally, researchers will reject a null hypothesis if the p-value is less than 0.05.
Responsible beverage service (RBS)
Randomised controlled trial (RCT)
The Relative Risk (RR) is used to compare the risk in the two different groups of people, i.e. treated and control groups to see if belonging to one group or another increases or decreases the risk of developing certain outcomes. This measure of effect will tell us the number of times an outcome is more likely (RR > 1) or less likely (RR < 1) to happen in the treatment group compared with the control group.
Practical interpretation
Interventions that obtained measures of effects in favour of the intervention, but that showed some limitations or unintended effects that need to be assessed before providing them. See the relevant module methodology page for further information.
Interventions for which there are not enough studies or where available studies are of low quality (with few patients or with uncertain methodological rigour), making it difficult to assess if they are effective or not. Interventions for which more research should be undertaken are also grouped in this category.
Additional information for prevention
For prevention interventions, this is also known as 'zero effect'.
A type of prevention intervention which aims to enhance students’ abilities in generic skills, refusal skills and safety skills.
The Standardised Mean Difference (SMD) is the difference in means divided by a standard deviation. Note that it is not the standard error of the difference in means (a common confusion). The standardized mean difference has the important property that its value does not depend on the measurement scale. It may be useful if there are several trials assessing the same outcome, but using different scales.
The z-score (aka, a standard score) indicates how many standard deviations an element is from the mean of the population.
The EMCDDA has defined ‘comorbidity’, in the context of drug users, as a ‘temporal coexistence of two or more psychiatric disorders as defined by the International Classification of Diseases, one of which is problematic substance use’. The World Health Organization (WHO) defines ‘dual diagnosis’ as ‘the co-occurrence in the same individual of a psychoactive substance use disorder and another psychiatric disorder’ (WHO, 2010). Since 2012, the World Psychiatric Association (WPA) has had a new Section for this issue, and has chosen to use the term ‘dual disorders/pathology’ for this Section (WPA, 2014).
There is evidence for the association between several mental disorders and substance use disorders, but the nature of this relationship is complex and may vary depending on the particular mental disorder (e.g. depression, psychosis, post-traumatic stress disorder) and the substance in question (e.g. alcohol, cannabis, opioids, cocaine).
Data on psychiatric symproms among people in treatment for drug dependence are sparse and results varied . For instance, prevalence figures for mood disorders vary from 5 % in an Italian sample of polydrug users (Di Furia et al., 2006) to 90 % in a sample of 150 patients from therapeutic communities in nine European countries (De Wilde et al., 2007).
Treatment options for co-morbid substance and psychiatric problems are based on combination of cognitive therapy and pharmacological interventions.