Joint Statement on dual disorders: addiction and other mental disorders

Nestor Szerman, Jose Martinez-Raga, Ruben Baler, Carlos Roncero, Pablo Vega, Ignacio Basurte, Lara Grau-López, Marta Torrens, Miquel Casas, Pedro Ruiz

The World Association on Dual Disorders, the WPA Section on Dual Disorders and the Spanish Society of Dual Disorders have joined forces to clarify that:

Addiction is a Mental Disorder, not a voluntary, self-indulgent act

  • Dual disorders is a term applied to people who have an addictive disorder and another co-occurring mental illness. It is related to interacting neurobiological and environmental factors involved in behaviors of substance and non-substance related disorders. Nobody chooses to become addicted, and addiction is not a matter of weakness of will, a consequence of self-indulgent behaviour or a result of the mere pursuit of pleasure.
  • The above mentioned national and international scientific associations have drawn up a statement supporting the notion that addictions are mental disorders in response to unfounded claims to this assertion.
  • Patients with mental disorders, including addictions, should have access to a multidisciplinary care model that integrates and/or coordinates the mental health network and the addiction network, thereby avoiding the so-called “wrong door syndrome”.
  • The mental/brain disorder model of addictions has yielded to the development of effective preventive measures, treatment interventions, and public health policies. However, the concept of substance use disorders and dual disorders as brain diseases continues to be questioned, possibly because the neurobiological basis of these compulsive behaviors have not been fully explained.

August 2017.- Addictive behaviors are mental illnesses, as evidenced by basic and clinical research in the field of the neurosciences. Neurobiological and environmental factors are involved in the behaviors underlying both substance (tobacco, cocaine, cannabis, alcohol abuse, …) and non-substance related disorders (gambling, sex, food, …). Although the recognition of addiction as a mental/brain disease has led to effective preventive measures, treatment approaches, and public health policies according to the World Association on Dual Disorders (WADD), the WPA Section on Dual Disorders and the Sociedad Española de Patología Dual (SEPD), this conceptualization is still being questioned by certain opinion groups.

As explained by Dr. Nora Volkow, Director of the US National Institute on Drug Abuse (NIDA), “One of the reasons why the concept of addiction as a mental illness continues to be questioned is perhaps the fact that neuroscientific research has only recently begun to shed light on the neurobiological mechanisms underlying these behaviors.”  In her opinion, “The concept of addiction as a mental illness or disease of the brain challenges deeply ingrained values about self-determination and personal responsibility that frame addictive drug use as a voluntary, hedonistic act (1).

Recent publications, albeit without  scientific evidences, question the advances in the field of neuroscience, considering addictive people as responsible of pursuing pleasurable and ultimately self-indulgent behaviors. In this regard, the SEPD would like to clarify that “nobody chooses to become addicted”. Whilst contact with drugs or substances with abuse potential is determined by social factors, vulnerability to addiction is determined by individual factors (2). Remarkably, only a small proportion of individuals exposed to licit or illicit drugs develop compulsive drug-seeking behavior and the vast majority of them have a co-occurring mental illness. This co-occurrence is what has been termed dual disorder. As clarified by the WADD, the SEPD and the WPA Section on Dual Disorders “Not everyone who uses drugs becomes addicted, and those that do become addicted do not choose to do so.”

In view of the above the World Association on Dual Disorders (WADD), the WPA Section on Dual Disorders and the Sociedad Española de Patología Dual (SEPD), have joined forces to draw up the following 10 points statement.

  1. According to the current international diagnostic classifications of the World Health Organization and the American Psychiatric Association, the ICD and the DSM, respectively (3), addictions are mental disorders, and like any other mental illness, they are not a problem of will power, character failure, or self-indulgence.
  2. There is solid scientific evidence that support the acknowledgement that addiction, like other mental disorders, is a brain disease, and this in turn has given rise to what is known as the “brain disease model of addiction”(1).
  3. As with other mental disorders, current diagnostic classification systems allow for a dimensional assessment of addictions: mild, moderate, and severe. Severe addiction can involve a stronger physiological component, relapse is common, and the condition can become chronic (3).
  4. The most severe clinical characteristics of addiction will develop in approximately 10% of persons exposed to addictive drugs. They will develop a mental illness termed substance use and/or addictive disorder. Their susceptibility or vulnerability is determined by the interaction of individual, genetic, psychopathological, and environmental factors (1).
  5. In the vast majority of cases addictions co-occur with another mental illness. This is a clinical condition identified or called dual disorders or co-occurring disorder (4). According to data from large epidemiological studies, at least 70% of addicted individuals have dual disorders, although current evidence suggests that this figure has probably been underestimated (5). Likewise, over 50% of people with any mental illness have a lifetime addictive disorder, as well (6). Current scientific evidence shows that addiction and a co-occurring mental illness are not separate disorders, but rather different, interacting, clinical conditions. They may occur simultaneously or sequentially, and may develop due to individual and environmental factors (7,8).
  6. Epidemiological studies have not analyzed behavioral addictions such as gambling disorder, which are now recognized as being equivalent to substance use disorders due to their clinical and neurobiological similarities. However, behavioral addictions, also occur in vulnerable people and in patients with co-occurring mental illnesses (9).
  7. Patients with addictive or dual disorders may also have other medical conditions, such as infectious diseases, as an integral part of the dual disorder process (10).
  8. Substances with addictive potential have different, and sometimes opposite, effects on different groups of individuals, hence the importance of a personalized or precision medicine approach (11). The concept dual disorders allows for an integral personalized bio-psycho-social approach in which treatment is tailored to the individual not the substance.
  9. Patients with mental disorders, including addictions, require access to a multidisciplinary care model that integrates and/or coordinates mental health network and addiction resources. The existence, as is often the case, of two separate treatment networks, one for addictions and another for mental illness, for a single patient leads to what is known as the wrong door syndrome. Any patient has the right for an adequate assessment by expert health care specialists and access to integrated, evidence-based treatments for dual disorders. The existence of two separate care networks is neither sufficiently effective nor sufficiently efficient, and, as shown by the Madrid epidemiological study, results in a failure to diagnose many patients with dual disorder, denying them access to integrated care (12,13).
  10. The concept of dual disorders, based on the neuroscience (14), a strongly multidisciplinary field, is the only guarantee that patients with addiction disorders, just like those with other mental illnesses, will be treated with an integrated approach that combines both biological factors and psychological and social support.

In the 1980s, in many settings, people with mental illnesses were integrated into the health care system, but this was not the case for patients with addiction disorders, who were excluded and assigned to discriminatory, differentiated networks. Accordingly, the above scientific societies would like to highlight the importance of “applying scientific knowledge from medicine, psychiatry, and psychology to the treatment of addictions and dual disorder. This treatment must be evidence-based, patient-centered, integrated, of a high quality, and freely available to all. This will help to avoid repeating past mistakes and at the same time prevent severe stigmatization of both patients and their families.”


  1. Volkow N, Koob G, McLellan T. Neurobiologic Advances from the Brain Disease Model of Addiction. N Engl J Med 2016;374:363-71.
  2. Volkow ND. Addiction and co-occurring mental disorders. Director’s perspective”, NIDA Notes 2007; 21:2.
  3. American Psychiatric Association. Diagnostic and statistical manual of mental disorders (5th ed.). Arlington, VA: American Psychiatric Publishing, 2013.
  4. Szerman N, Martínez-Raga J, Peris L, Roncero C, Basurte I, Vega P, Casas M. Rethinking Dual Disorders/Pathology. Addict Disord Their Treat2013; 12:1–10.
  5. Arias F, Szerman N, Vega P, Mesias B, Basurte I, Morant C, Ochoa E, Poyo F, Babín F. Madrid study on the prevalence and characteristics of outpatients with dual pathology in community mental health and substance misuse services. Adicciones. 2013;25(2):118-27.
  6. Lev-Ran S, Imtiaz S, RehmJ,LeFollB. Exploring the association between lifetime prevalence of mental illness and transition from substance use to substance use disorders: results from the National Epidemiological Survey of Alcohol and Related Conditions (NESARC)”, Am J Addict 2013; 22:93-98.
  7. Leyton M, Vezina P.Dopamine ups and downs in vulnerability to addictions. A neurodevelopmental model. Trends Pharmacol Sci. 2014;35(6):268-76.
  8. Szerman N, Martinez-Raga J. Dual disorders: two different mental disorders? Adv Dual Diagn 2015; 8:1-4.
  9. Kessler RC, Hwang I, laBrie R et al. DSM-IV pathological gambling in the National Comorbidity Survey Replication 2008; Psychol Med 38: 1351-1360.
  10. Roncero C, Barral C, Rodríguez-Cintas L, Pérez-Pazos J, Martinez-Luna N, Casas M, Torrens M, Grau-López L. Psychiatric comorbidities in opioid-dependent patients undergoing a replacement therapy programme in Spain: The PROTEUS study. Psychiatry Res. 2016 Sep 30;243:174-81. doi: 10.1016/j.psychres.2016.06.024. Epub 2016 Jun 17. PubMed PMID: 27416536.
  11. Van Os J, Delespaul P, Wigman J, Myin-Germeys I, Vichers M. Beyond DSM and ICD: introducing “precision diagnosis” for psychiatry using momentary assessment technology: World Psychiatry 2013 12; 2: 113-117
  12. Minkoff K. Individuals with Co-occurring Psychiatric and Substance Use Disorders. Psychiatric Services 2001 Vol. 52, 5: 597-599.
  13. Greenfield SF and Weiss RD. Emerging topics in addiction. Introduction. Harvard review of Psychiatry 2015; 23 (2): 61-62
  14. Volkow N. Drug abuse and mental illness: progress in understanding comorbidity. Am J Psychiatry 2001; 158:1181-1183.

About WADD

The World Association on Dual Disorders (WADD) is a non-profit association founded in 2015 during the IV International Congress on Dual Disorders. Its mission and goals are to increase the Knowledge and education on Dual Disorders, increase the awareness of Dual Disorders worldwide and offer a platform for all dual disorders professionals, promote the research on dual disorders and reduce the stigma related to Dual disorders

About  SEPD

The Spanish Dual Pathology Society (SEPD) is a world leader in the field of dual disorder. It is a not-for-profit scientific-medical society founded in 2005 with over 2000 members from many disciplines who work as clinicians, educators, and/or researchers in the field of dual disorder.

The aim of the SEPD is to provide training and promote research, development, and innovation in the field of dual disorder and to increase awareness of the associated challenges among health care professionals, government bodies, and society in general.

The “Internet and Psychiatry” received this Statement for publication from Dr. Nestor Szerman.