Dual diagnosis is defined as the comorbidity of a substance use problem and a psychiatric disorder of a person. Drug addiction is a growing public health problem. The United Nations Office on Drugs and Crime (UNODC) reported a progressive increase in the prevalence of a substance use problem from 3.5% to 5.7% from 2008 to 2010; a new increase from 5.7% to 7% between 2010 and 2012, which represents 324 million consumers worldwide. About 60% to 80% of this population presents this dual diagnosis. Prevalence of a personality disorder and a substance use problem comprises 20% to 50%. Prevalence between a depressive disorder and a substance use problem goes from 12% to 88%. Prevalence between anxiety disorders and substance use problems is from 10% to 24% and between bipolar disorder and substance use from 51% to 60%. The importance of the paradigm shift in the addiction treatment includes mixed models of intervention where substance use disorders and comorbid psychiatric disorders are contemplated. They are necessary because they help preventing a relapse, the increase of costs for the family, that the attention gets divided in different physical spaces, the application of different therapeutic techniques and that the pharmacological treatment is not oriented to treat substance use disorder as it is oriented to treat psychiatric comorbidities. Therefore it is necessary to implement a comprehensive vision and a specific approach for each disorder of the patient.
Keywords: Addiction, dual diagnosis, etiology of the dual diagnosis, co-morbidity, paradigm shift.
In psychiatry and addictology, the term dual diagnosis refers to the coexistence of a substance use disorder and a psychiatric disorder in the same person. There is an important number of reasons why those problems have currently received greater attention. In the first place, there are many studies that show a disproportionate number of people with a substance use disorder that also have a psychiatric disorder; in second place, the opposite is true: a high proportion of psychiatric patients suffer from a disorder because of their substance abuse. Prevalence of dual diagnosis varies widely. According to the National Comorbidity Survey, about 10 million people in the United States have had a dual diagnosis in 1991 (60% men and 70% women).  There are three ways of interpreting dual pathology: both the psychiatric disorder and the substance dependence may have common biological, psychological and social causes; the use of drugs or alcohol by itself may lead to psychiatric symptoms; and people with a psychiatric disorder may develop an addictive disorder as a form of self-medication. From a clinical and social perspective, dual pathology represents a therapeutic challenge. These people use the emergency services more, they require more psychiatric hospitalizations, they show risky behaviors, HIV infections, Hepatitis C virus, unemployment, marginalization and more violent behaviors. Dual Pathology, as a new paradigm, requires and demands integrated models of prevention and treatment to be successful, which would call the current health care services model (public and private) into question, a model that supports an important division between the treatment for substance use disorders and the one for psychiatric disorders.
Addiction is defined as a set of maladaptive behavior patterns that produce an inability to control the consumption of a substance despite its negative consequences on several areas of the individual's life. It is also a behavior heading towards the imperative satisfaction of an appetitive affection, derived from being exposed to an addictive agent (gambling, sex, video games, licit and illicit substances, etc.) and it is characterized by a recurring concern for this appetitive behavior, the imperative and immediate need for its temporary satisfaction and the loss of control over this behavior, which results in adverse events affecting the family, social and medical function,7 whose biological substrate is located in the brain’s reward system and the prefrontal cortex.
The etiology of addiction is multifactorial. Among the risk factors for the development of an addictive behavior stand out intrinsic factors such as genotype, sex, age, age of first consumption, previous addictive behavior or a pre-existing psychiatric disorder. Among the external factors are the availability of the addictive substance, social approval, a dysfunctional family and raising patterns, child abuse and socioeconomic status. A third element could be the nature of the addictive agent (psychoactive and pharmacokinetic properties, and usage).
The addiction to a licit or illicit substance includes not only the abuse and dependence to that substance, but also the stages of production, trafficking, distribution, consumption, social, economic and medical consequences; it also affects all groups of population and has important implications for a nation’s public health.
Addictions are a growing public health problem, illicit drugs contribute with 0.8% and alcohol with 0.7% of global deaths and disability. Only in the United States they represented a total expense of 180 billion dollars in 2002 of which 16 billion were used for health care services for substance use, 30 billion were used to combat crime derived from substance trafficking, and 134 billion dollars due to the loss of productivity of economically active population.
In Mexico, the total costs of the drug problem increased from 352 million dollars (0.09% of GDP) in 1998 to 660 million (0.11%) in 2002, then the fell to 618 million (0.1%) in 2003. In that same year, the most important cost item was the supply reduction (66.0% of the total), followed by productivity losses (23.4%), health and prevention (9.1%) and property damage (1.6%). However, expenses on public safety associated to drug trafficking has continued to rise. Only, in 2010, 53 billion pesos were invested in public safety compared to the investment in programs against addictions, that was only of 6.8 billion between 2007 and 2012.
Global substance consumption continues to rise progressively regarding the world’s reports on addictions conducted in 2008 and 2010 by the United Nations Office on Drugs and Crime (UNODC). This last year, it was reported a significant increase from 3.5% to 5.7% (155 to 250 million users) of the prevalence of substance consumption throughout life, and in 2012, it was reported a new increase of 5.7% to 7% (162 to 324 million people).
Prevalence of problematic users remains relatively stable throughout 2008, 2010 and 2012 with a prevalence of 10% to 15% (16 to 38 million people). Health care for addictions, unfortunately, continues stable; only one in seven problematic users receive specialized medical attention (70% of all problematic users, that is, between 11 and 33.5 million problematic users).
Mexico shows a continuous upward trend in relation to the consumption of illicit and non-prescription drugs throughout life with an increased prevalence from 1.6% in 2008 to 1.8% in 2011. The use of marijuana, first illicit drug that had an impact on Mexican population, increased from 1.0% to 1.2% between 2008 and 2011. Cocaine, the second most consumed drug, showed an increase from 0.3% to 0.5%. From 2008 to 2011, 100,000 people were added as dependents on some illicit substance (from 450,000 in 2008 to 550,000 in 2011). Prevalence of substance use remains predominant in males (1.3%) with respect to women (0.2%) and, from 2008 to 2011, men’s consumption went from 2.8% to 33.3% and women’s consumption remained in 0.9%. The average age of the first illicit substance consumption of Mexican population was set at 18.8 years old. Regarding alcohol (first substance consumed in Mexico), it showed an increased consumption from 4.1% to 5.5% between 2002 and 2008. In the same period, significant increases were registered in relation to consumption by sex (8.3% to 9.7% in men and 0.4% to 1.7% in women). In terms of regional distribution, the Northern part of the country still has the highest prevalence of illicit substances consumption, especially in Tamaulipas, and in the center of the country, the State of Hidalgo. Increased use of licit and illicit substances in Mexico has several explanations, among them are the demographic growth, the rapid urbanization rate and the closing of the consumption gap between men and women.
Epidemiological studies that have been performed since the 80´s have demonstrated the existence of important statistical associations that demonstrate the high prevalence of co-occurring Substance Use Disorders and other Psychiatric Disorders. In most cases, co-occurrence indicates the interaction of several diagnostic psychopathological categories, that is, a person with a substance use disorder may have more than one comorbid psychiatric disorder. This co-occurrence has been called in different ways: Co-occurring Disorders, Dual Diagnosis, Dual Disorder or as it has been called in Spanish: Dual Pathology.
Dual Pathology negatively impacts the quality of life and the biopsychosocial functioning of individuals who has it, because the coexistence of a substance use disorder and a psychiatric disorder is associated with high seriousness rates of the addiction and the co-occurring psychiatric symptoms, suicidal behaviors (ideation and suicide attempts), greater use of medical services, emergency services, psychiatry and addiction, relapses and treatment abandonment, risky sexual behaviors (multiple partners and unprotected sex), HIV infection, Hepatitis B and C and other sexually transmitted diseases, violent and criminal behavior, imprisonment, indigence, loitering, and social adjustment problems of labor, scholar, and financial type, besides family burden.
Prevalence of dual diagnosis varies widely according to the methodology that is used, the selection of cases, the types of conducted interviews and the where epidemiological studies are carried out, which generates a wide variety of prevalence. Nevertheless, a range from 20% to 50% is commonly accepted in general population and a range from 40% to 80% in clinical population. The Epidemiological Catchment Area study (ECA), carried out in 1980, found that 45% of alcoholics and 72% of illicit substance users had a psychiatric disorder. The National Comorbidity Survey (NCS), conducted in the United States in 1991, reported that 10 million people had a dual diagnosis; 60% of men and more than 70% of women diagnosed with alcohol dependence had at least one psychiatric diagnosis at some point in their lives. An odds ratio (OR) of 2.4 was reported for comorbidity throughout the life of any psychiatric disorder, assessed by the DSM III-R, and an alcohol consumption or other drugs disorder. About half (51.4%) of the participants in the study with a substance use disorder met the criteria for a comorbid psychiatric disorder at least once in their life, while 50.9% of the participants who had a psychiatric diagnosis met the criteria for a substance use disorder. Prevalence after 12 months of psychiatric disorders for substance users was 42.7% and for those who had a psychiatric diagnosis, the prevalence was 14.7% for substance use. In 2001, the National Household Survey on Drug Abuse, conducted in the United States, reported a co-occurrence of 20% of alcohol dependence and illicit drugs in patients with severe psychiatric disorder. A pilot study on prevalence of dual diagnosis in patients under treatment in the Community of Madrid showed a prevalence of dual diagnosis of 34% of the total sample. They were distributed in 96 subjects from the drug network (70.59% of dual patients and 36.78% of patients treated in drug centers) and 40 from the mental health network (29.41% of all dual patients and 28.78% of patients treated in the mental health network); the most common psychiatric diagnoses were mood disorders, personality disorders and schizophrenia. However, the study of Madrid on the dual diagnosis prevalence in cannabis users showed that 76.5% of cannabis addicts had a dual diagnosis with a higher prevalence of mood and anxiety disorders, and 51% cannabis addicts had a diagnosis of personality disorder. In England, most dual pathology studies have mainly focused on groups of patients with a severe mental disorder associated with a substance use disorder, prevalence ranging from 5% to 68%.
The World Health Organization (WHO) recommends the development of strategies to deal with addictive disorders in populations with specific needs such as indigents. In this population, sleeping and living in the streets, shelters or temporary refuges, a prevalence of dual diagnosis has been established, ranging from 10% to 60%, being the non-affective psychosis, anxiety and mood disorders the most common ones. Nielsen et al., in 2011, conducted a study that included 32,711 medical records of indigents, 62.4% of men and 58.2% of women had any psychiatric diagnosis associated to substance use with a higher risk of morbidity for dual pathology in women than in men.
Prevalence of dual diagnosis in prisoners includes a range from 6% to 43%; prevalence of psychiatric disorders occurred in 50% to 70% of the prisoners; and prevalence of substance use disorder was of 11% to 42%. The main psychiatric disorders that were registered in prisoners included the antisocial personality disorder, anxiety disorders, mood disorders, attention-deficit/hyperactivity disorder and non-affective psychosis. The differences in the prevalence of psychiatric disorders between genders included a higher frequency of antisocial personality disorder, non-affective psychosis and anxiety disorder in men; and in women prevailed eating disorders, posttraumatic stress disorder, attention-deficit/hyperactivity disorder and borderline personality disorder.
Women are more vulnerable to drug and substance use, prevalence of dual diagnosis is higher in women than in men, with an overall prevalence of 65% in women, compared to 44% in men. One of the risk factors associated with dual pathology in women is a history of child abuse, sexual abuse and gender violence, with a prevalence of substance use and psychiatric disorders of 55% to 99% in this group.
Prevalence of dual diagnosis in senior citizens goes, in several studies, from 21% to 66%. The most common psychiatric disorder is depression, which is associated with alcoholism. The association between alcohol consumption, depressive disorder and anxiety has a causal relation with 70% of suicides reported in this population.
In Mexico, there are only two studies on prevalence of dual diagnosis. The first one, conducted by Marin-Navarrete et al. Mutual-Aid Residential Center for Addiction Treatment showed a prevalence of dual pathology of 75.2%. Among addicts to any illicit drug, a prevalence of 85.9% was reported, in alcohol addicts a prevalence of 78.9%, and 70% of the sample had more than two psychiatric disorders of axis I.
In the second study, conducted by Rodrigo Marín-Navarrete, Ana de la Fuente-Martin et al., a psychiatric interview was performed to women receiving treatment in two Mutual-Aid Residential Center for Addiction Treatment. Population’s disorders and characteristics were compared to previous treatments. Differences in medical prescriptions over time were analyzed in a hundred women who were recruited with dual diagnosis. Thirty of them said not being receiving previous treatment and less than 20% reported a previous treatment. Patients with borderline personality disorder presented one third of the probability of reporting previous pharmacological treatments with respect to other patients without this medical condition (OR=0.33, 95% CI 13-84). Significant differences were found in taking antidepressants (17.6% vs 41.8%; p<.05), mood modulators (12.1% vs 32.7%; p<.05), antipsychotics (15.4% vs 48.0%; p<.05) and others (4.4% vs 29.6%; p<.05).
Different non exclusive biological theories have been proposed to understand the phenomenon of addiction as a reward deficiency model, a model of incentives and a model of allostasis, each of these models has unique characteristics, but have an element in common: the motivation or reward neurocircuit. In these models, the cortico-striato-thalamo-cortical pale loops form a central element underlying all rewarding behaviours. Other brain regions and circuits significantly contribute to motivational behaviors, like the amygdala, which is an important source of emotional information related to the addictive stimulus; the hippocampus that provides information on contextual memory and associates such conduct with instrumental memory; hypothalamus and septum determine the homeostatic control resulting from the changes induced by the addictive behavior in the Hypothalamic-pituitary-adrenal (HPA) axis; and the insula is related to the interoceptive processing. Each of these elements is involved in the neurobiology of addiction. The addictive process is established through neural long-term changes (neuroplasticity), which are responsible for establishing the characteristic behaviors of such process, like craving, the compulsive search for the addictive behavior and relapse.
Three hypotheses had tried to explain the relationship of dual disorders. Today, it is postulated that:
Firstly, two or more independent factors between each other: each of them has different clinical pathways and independent treatments. This co-occurrence can be explained by and independent biological model: both factors are independent. In the model of a common factor, both disorders are caused by the same predisposing factor.
Secondly, the model of substance use primary disorder: the substance use primary disorder influences the development of a secondary one and, once a secondary disorder has been developed, they take independent pathways. Both medical conditions can be treated for as long as necessary.
Thirdly, the model of the primary psychiatric disorder: the secondary disorder appears to mitigate the problems associated with the primary disorder. By solving the primary disorder, the secondary one will dissapear.
The overall prevalence of personality disorders (PD) widely varies in different epidemiological studies fluctuating from 2.5% to 5.9%. The National Epidemiologic Survey on Alcohol and Related Conditions (NESARC), conducted in the United States, indicates comorbidity in 28.6% of alcohol consumers and some personality disorder (PD), and a comorbidity of 47.7% in consumers of other illicit substances and some personality disorder, while 16.4% of individuals diagnosed with a personality disorder showed a comorbidity of 6.5% of alcohol dependence and other illicit substances. Disorders related to alcohol or other illicit substance use were the antisocial, histrionic and dependent personality disorders. Associations of obsessive-compulsive, histrionic, schizoid and antisocial disorders with specific substance use disorders were significantly stronger in women; while in men, the associations were mostly between dependent PD and substance dependence. In Spain, a recent epidemiological study on dual diagnosis, promoted by the Spanish Society of Dual Pathology and carried out in a clinical population claiming for assistance, obtained a prevalence of personality disorders of 71%. The PDQ4+ interview was used as a measuring instrument, which allowed to appreciate the presence of depressive (25%), borderline (25%) and paranoid (24%) disorders, followed by avoidant (23%), obsessive-compulsive (22%) and antisocial (20%) disorders.
Epidemiological studies show a high prevalence and association between affective disorders and substance use disorders. The co-occurrence of depressive disorders and substance user disorder in studies that were carried out in a population of consumers is between 12% and 88% in samples of patients receiving outpatient treatment, and 27% in patients that have not requested treatment. On the other hand, the existence of a major depressive episode has been associated with a substance use disorder.
In a recent study carried out by the Spanish Society of Dual Pathology, it is estimated that almost one third of patients with dual pathology (28.76%) meets the diagnostic criteria for a major depressive episode. There is a statistically significant association between the presence of suicide risk and dual diagnosis (41.35 vs. 13.52%; p<0.0001). For this reason, depressed patients associated with substance use must be the key objective of the diagnostic and treatment, because this association involves an added risk.
The Epidemiological Catchment Area (ECA) shows that nearly 24% of patients with anxiety disorders suffer from a comorbid substance use disorder throughout their lifetime (17.9% present a diagnosis of abuse or dependence and 11.9% present a diagnosis of alcohol abuse or dependence to other drugs). On the other hand, 19.4% of patients diagnosed with alcohol abuse or dependence will develop, throughout their life, a comorbid anxiety disorder, and prevalence throughout life goes up to 28.3% in the case of abuse or other drugs dependence diagnosis (27.5% for cannabis, 33.3% for cocaine, 31.6% for opiates, 42.9% for barbiturates, 32.7% for amphetamines and 46.0% for hallucinogens). Data derived from the National Comorbidity Survey Replication (NCS-R) indicate that 27% of patients with panic disorder without agoraphobia suffer from a comorbid substance use disorder and goes up to 37.3% for panic disorder with agoraphobia. Similarly, the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) showed that the prevalence found in the last year between the comorbidity of substance use disorder and anxiety disorder was around 18%; specific phobia was the most frequent comorbidity (10.5%). However, disorders that have a higher risk of comorbidity (risk that appears in population with substance use with respect to populations that are not exposed to drugs use) include: panic disorder with agoraphobia (OR= 3.1), generalized anxiety disorder (OR=2.3) and panic disorder without agoraphobia (OR=2.1).
In the specific case of generalized anxiety disorder, which is one of the anxiety disorders that presents more diagnostic difficulties in drug users, the last data obtained from this study show that the prevalence of generalized anxiety disorders and substance use disorders is 2.04%; while prevalence throughout the life of anxiety disorders not associated with substance use disorder is from 2% to 10%. Half the patients suffering from a generalized anxiety disorder all their life, have a dual pathology. On the other hand, dual patients show a series of different characteristics, like an increased frequency in males or a family history of alcohol and other substance use. The European Study of the Epidemiology of Mental Disorders (ESEMeD) found an association statistically significant between alcohol abuse or dependence and different anxiety disorders, finding a high risk in the association between alcohol dependence and anxiety disorders, (OR=11.2) and agoraphobia (OR=10.7).
The Epidemiologic Catchment Area (ECA) study observed a prevalence throughout life of 56.1% for any substance use disorder in a sample of individuals with bipolar disorder. In individuals with bipolar disorder type I, the prevalence was 60.7%, and for type II it was 48.1%. The National Comorbidity Survey Replication (NCS-R) study did not only evaluate the bipolar disorder type I and type II, but also prevalence and comorbidities associated to sub-threshold bipolar disorder, defined as a disorder where manic and depressive alternating phases are not evident and do not meet the diagnostic criteria for a manic or depressive episode in DSM-IV. In this study, comorbidity with substance use disorder was high in all subtypes of bipolar disorder, but especially in type I. Prevalence throughout life of alcohol abuse for bipolar disorder type I was of 56.3%, for bipolar disorder type II was 36% and for sub-threshold bipolar disorder was 33.2%. Regarding the use of any drug, bipolar disorder type I had a prevalence of 30.4%, bipolar disorder type II of 30.4% and sub-threshold bipolar disorder of 8.7%.
ADHD has a high comorbidity with other psychiatric disorders throughout all stages of life. In childhood and adolescence with defiant conduct disorders, learning, anxiety and mood are the most frequent psychiatric comorbidities. In adults, comorbid conditions of ADHD are similar to those detected in previous stages of life, in spite of observing a higher prevalence of personality disorders and substance use disorder. It has been estimated that at least 60% to 80% of patients with ADHD have other psychiatric comorbid disorder.
One initial difficulty is that most of the professionals are experts in only one field, either mental health or substance use. These patients receive a “revolving-door” attention. They approach either the mental health care system or a substance use treatment program and then, other program is mentioned on behalf of the professionals. Sometimes, each of these systems refuses to treat them due to problems involved in the treatment of a combination of symptoms. For this type of patients, it is necessary to create a separate treatment model, combining the attention to a substance use problem and the attention to a patient’s mental pathology, according to his/her individual personality traits.
Many factors are related to the combination of substance use and mental health. The type of substance that is consumed and its effect on the quality of the individual are important, as well as its personality traits and the nature of the mental illness. Substance abuse may have both a positive and a detrimental effect on the patient, since the substance may be a medication and medications can be abused. The effect on each patient can vary at different moments in time.
Comorbidity between a substance use disorder and a psychiatric disorder involves a challenge to treat comorbid addictions and psychiatric disorders. At least in Mexico, there is no health care system that involves the treatment of both conditions. On the one hand, it has a system of units called CAPA (attention center to prevent addictions) where having a psychiatric disorder is an exclusion criterion for the attention of a person with a substance use disorder; besides there are no specialized spaces for a comprehensive treatment of these patients in the psychiatric hospitalization units; furthermore, there are no spaces in the health care units for addictions to give a comprehensive treatment to addicts that have a psychiatric disorder.
A third option to treat addictions, at least in Mexico, is the empirical proposal called "Anexo" or Mutual-Aid Residential Centers where the voluntarily or involuntarily detention is possible for periods of at least three months to one year and whose philosophy of care is based on the Alcoholics Anonymous (AA) program, also 24% of the directors of these residential care facilities only have a high minimum level of education, 31% have upper secondary education and 19%. The education of the staff that works with addicts in these rehabilitation centers is minimum; 58% of individuals involved in patients’ care only have specialized studies in addiction, 33% and only 2% have a bachelor’s degree. Only 20 % of the 394 “Anexos” for the attention of patients with an addictive disorder that are officially registered in the State of Mexico comply with the General Health Law.
The lack of physical space for the comprehensive treatment of patients with dual diagnosis is due to the allocation of only 2% of the financial budget to mental health care programs. Of this 2%, 80% is allocated to the maintenance and administration of psychiatric hospitals. A second element involved in the overall mental health care, particularly in addictions, is the therapeutic nihilism, which means insufficient training of health staff at all three levels of addictions care and mental health problems. A third element is the lack of implementation of intervention protocols and, when they exist, they are implemented inadequately and inefficiently, making imperative the evaluation of functionality.
The stigma of the patient requesting mental health care resources is another element that hampers a comprehensive addiction treatment. It must be added the lack of staff assigned to mental health care services in Mexico: 1.6 psychiatrists; 1 physician; 3 nurses; 1 psychologist; 0.53 social workers; 0.19 therapists /100.000 habitants.
Medina Mora recommends to treat the phenomenon of addiction from a multimodal perspective; to evaluate the interaction between the substance, the people and the context of use; to strengthen the epidemiological research; to invest in training for addictions’ care, prevention and a comprehensive treatment; to approach the problem in a comprehensive way centered in the offer, the demand and the context, increasing universal and selective prevention.
The coexistence of a disorder, a substance use and a psychiatric disorder involves the worst prognosis in the evolution of a disease, a higher demand for specialized medical and social attention, and a greater social and psychological debilitation. It also involves a greater financial burden for the patient’s relatives in comparison to other chronic diseases such as diabetes mellitus and asthma. Therefore, it is essential to evaluate how it affects family dynamics during the development, evolution and prognosis of comorbidity between substance use disorders and psychiatric disorders.
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[a] Corresponding author:
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