In the approach to mental disorders, including addiction, we can distinguish a number of waves. Such waves exist relating to the following topics:

Many historians begin their history of psychiatry shortly before 1800, because only then there were, on a relatively larger scale, medical centres specifically for people with mental disorders. Moreover, only in that period there were doctors who were specialized in psychopathology. However, psychiatry is in fact of much older date and actually runs parallel to the history of medicine in general. The ancient Greek, Roman, Muslim, and Christian doctors focused both on physical and psychological symptoms. It is even questionable whether they—like we have become accustomed to—made such a distinction between mental and physical illnesses. See Sadock et al. (2009) for a compact but well-documented overview of the history of psychiatry.

Important events in the history of modern psychiatry are in the first place the humanization of the psychiatric centres and the ‘moral’ therapy that was brought into practice. As far as we can ascertain, the conditions in the still scarce psychiatric institutions in the eighteenth century, were pitiful. There was no or hardly any therapeutic policy. Patients were locked up as imbeciles, idiots, or insane people and more or less left to their own fate. This changed gradually around 1800. The establishments became more humane and a search for effective therapies began. This can partly be traced back to the works of Philippe Pinel (1745–1826) and Jean-Étienne Dominique Esquirol (1782–1840). Pinel is in our memory the symbol for the literal liberation of psychiatric patients from their chains. This took place at the end of the eighteenth century in the Parisian Hôpital Bicêtre. His commitment marks the development of psychiatry as a medical discipline: ‘lunatics’ became ‘patients’. Of interest, this action is falsely attributed to Pinel. In fact, it was his assistant Jean Baptiste Pussin who did this historic act in 1797.

The ‘moral therapy’—we would now speak of psychological treatment—was based on the idea that mental disorders were the result of genetic as well as environmental influences. The treatment was focused on education and (on belief-oriented) conversations with patients. This therapy worked only modestly. Therefore, psychiatrists also sought refuge in other, in our eyes sometimes ‘barbaric’, methods. In this way, they tried to call agitated patients with bizarre, violent (or aggressive) behaviour to order. However, this did not have a truly therapeutic effect.

In the first half of the twentieth century, experiments were done with limited effective biomedical interventions. Examples are inducing fever using malaria infection to treat psychotic symptoms as a result of general paresis. Real results were only realized when, starting from the middle of the twentieth century, chemicals were discovered that proved efficacious for the treatment of mental disorders. Examples of disorders that could be treated with medications are schizophrenia, bipolar disorder (manic depression), depression, or anxiety disorders. The advent of antipsychotic drugs for the treatment of patients with schizophrenia contributed to a substantial decline in the number of psychiatric hospitalizations.

As a result of different views about the treatment of psychiatric patients and strong criticism on the large psychiatric hospitals (often far away from the population centres), a movement to de-institutionalize psychiatry arose. The aim was to reduce the number of inpatient admissions, to reduce the dependence on caregivers and to rehabilitate the social position of psychiatric patients. It was realized that it makes sense to help those affected to reintegrate in society and to increase their self-reliance, despite having a chronic mental illness. Psychiatric patients were people with a mental limitation, but with plenty of opportunities for a humane existence.

In psychiatry, the biological dimension has from time to time been emphasized. An example of this is the German physician Wilhelm Griesinger (1817–1868) who stated that all mental disorders are ‘brain diseases’. Therefore, psychiatry had to be a medical discipline. At the same time, there are people who have stressed the importance of the psychological and social dimensions (without neglecting the biological). Influential was the American Adolf Meyer (1866–1950), who developed the concept of psychobiology. In the wake of this, he introduced psychosocial treatments. Meyer also advocated that patients had to be treated as much as possible in their own environment.

In the 1970s, the American psychiatrist George Engel (1913–1999) proposed the biopsychosocial approach to illness, which he presented as an alternative to the traditional biomedical approach. This is focused on the treatment of diseases or on the related symptoms, but there was little attention for the psychosocial context in this approach (Engel 1977; Frankel et al. 2003). The biopsychosocial approach is based on system theory. It was a very important innovation and has been of immense significance, especially for psychiatry. Engel insisted on looking at different levels, from the perspective of different disciplines. He considered the tangle of problems that often exist with different types of health problems, while stressing the importance of paying attention to the complexity of such problems. This was better than to reduce them to separate components or separate aspects. Apart from psychiatry, this way of thinking has especially taken hold in general practice.

Engel (who would have had no qualms to add also the cultural dimension to his biopsychosocial approach), made it clear that the biopsychosocial approach holds true for schizophrenia as well as for diabetes or addiction. He pointed out that regardless of what the aetiology is of a condition, a layered and multi- or interdisciplinary approach is always preferable compared to the traditional biomedical approach. Schizophrenia and diabetes are in this perspective both a ‘somatic’ condition as a ‘mental’ condition. And social problems can be part of both illnesses: when the course is chronic, the consequences of the condition are not limited to one level or domain.

Engel was far ahead of his time in theoretical terms and built on the insights of Adolf Meyer. In the practice of medicine in a broad sense, the consequences of his approach are far from being understood. Moreover, there is the continuous risk of a relapse in the classical biomedical approach. In this sense, his approach is still very ‘modern’.

The relevance of the biopsychosocial approach is particularly reflected in the transition that currently takes place in mental health: the recovery-oriented care. Serious mental disorders take for a large part a chronic course. ‘Healing’ is not possible for this group. On the other hand, in biopsychosocial and cultural terms, there are many possibilities for those concerned to recover.

Under the name of evidence-based medicine there exists, from the end of the twentieth century, a movement to review medical procedures as much as possible by experimental, scientific research. Based on the outcomes are subsequently treatment recommendations and guidelines designed, which also happens in psychiatry or substance abuse treatment. Before, there were initiatives going on to test interventions in experiments, but there was still a lot of critique or doubts regarding the methods that were used. And there were no databases yet that could quickly determine whether an intervention or therapy was working, and that such a ruling was based on evidence. Nowadays, statements about the strength or weakness of a recommendation are based on the analyses of a series of experiments in a laboratory. Then, these are tested in practice. The randomized controlled trial (RCT), a randomized and controlled trial in which ideally the subjects do not know which treatment they undergo, now has the status of ‘gold standard’. The evidence-based medicine has a long history. Philippe Pinel, one of the founders of modern psychiatry, advocated for more than 200 years ago the use of statistics for making statements about treatment methods.

Substance abuse treatment is younger than the general mental health services or psychiatry, although there are many parallels with the description above.

In many cases, relatively independent of psychiatry or mental health care, separate institutions for addiction treatment have been established in most countries in Europe. There were initiatives from the nineteenth century when organisations for the temperance movement emerged. Just as in psychiatry, the attention was first focused on asylums or clinics for alcoholics, but also outpatient facilities arose gradually. Until the 1960s, the attention was concentrated mainly or exclusively on problems with alcohol. However, the rise of illegal drugs from the seventies of the twentieth century (such as heroin, amphetamine, cannabis, cocaine, and years later ecstasy) led to a boom in new centres. These were partly the same facilities targeted on alcohol problems, but a large number of facilities focused exclusively on issues related to drug use. This separation is understandable because the target groups, and their social backgrounds, were different from one another. The rise of the Human Immunodeficiency Virus (HIV) that causes Acquired Immune Deficiency Syndrome (AIDS) gave the drug services in the 1980s even more clearly its own distinct position: the discussion thrived on the question if harm reduction, by improving the sanitary conditions of drug users (distribution of condoms for safe sex, swap used syringes for clean ones), was not more important than achieving abstinence as the primary purpose of the care.

Finally, also the importance of a biopsychosocial-cultural approach is relevant to the substance abuse treatment. The same applies to working according to evidence-based guidelines.

For the treatment of people with addictions and a co-morbid or co-occuring mental disorder (or vice versa: dual disorder), it is of great importance that there are facilities available that are able to respond adequately to both problems. In no country, in Europe or elsewhere, this is the rule. In most countries there are—often already since the nineteenth century, or longer ago—psychiatric hospitals. After World War II, in the one country faster than in the other, ambulatory facilities emerged also. Even more recent is the closure of these hospitals or at least a reduction in the number of beds. But, as a rule, the attention to addiction problems was and is herein limited, or secondary. This has to do with the fact that addiction—to this day—is not nearly everywhere and by everyone recognized as a mental disorder. Indeed, the ICD and the DSM—in various editions—have listed addiction definitely as illness or disorder. In public opinion, but also by many clinicians, addiction is often approached as something special: for example as a form of deviant behaviour, as an expression of moral weakness, or as a form of crime. This has resulted in a situation where drug addicts or alcoholics were not—as a matter of course—admitted to psychiatric (ambulatory or clinical) facilities. That does not mean that there were (and are) not a lot of people with addiction problems that were hospitalized. This has always been the case: the prevalence of use, abuse and dependence of people with a mental disorder is, compared to the general population, relatively high. This means that even though the policy was and is aimed to ward off people with addiction problems, it is unlikely that this really was successful.

Together, a landscape was created in which facilities for alcohol and drugs emerged relatively independently from each other, and often still function apart from each other. This has inevitably consequences for the organizational conditions of the treatment of people with dual disorder problems. Caring for people with addictions is—unfortunately—not a natural part of mental health institutions. And the reverse is also true: the treatment of co-morbid mental disorders in substance abuse treatment is not standard practice. Even if one would like to do this, there is often a lack the skills and resources. What often happens is that clients or patients will be referred between services for addiction and mental health. This happens as soon as a mental disorder of a client in substance abuse treatment is so severe that psychiatric intervention is necessary. Conversely, a patient can be referred to a service for addiction care when the substance use is so strong that this frustrates a psychiatric or psychological treatment.