Chapter 2

The Problem of Dual Diagnosis

Dual Diagnosis and Comorbidity

• Dual diagnosis– Describes individuals who meet diagnostic criteria for

a mental disorder(s) along with one or more substance use disorders

• Comorbidity– Combinations of any types of psychiatric disorders

that co-occur in the same individual• More than half of patients in psychiatric

treatment meet criteria for more than one diagnosis

• Factors that affect rates of dual diagnosis: – Demographics (e.g., age and sex)• Males and those of younger age are more likely to

abuse substances– Inpatient or outpatient status and chronicity of illness• More severely impaired inpatients (e.g., schizophrenics)

are less likely to abuse substances than are patients who are less ill

– Setting • Hospital emergency rooms reflect higher estimates

than other settings

Dual Diagnosis: Methodological Issues in Determining Prevalence Rates

• Definitions of what constitutes dual diagnosis are far from uniform– Studies often use differing definitions and

measures of substance use disorders, making prevalence rates diverse and difficult to compare

Dual Diagnosis: Methodological Issues in Determining Prevalence Rates cont.

• Methods used to determine psychiatric and substance use diagnoses can influence findings– Research with clinical samples will often employ

less-standardized assessments– Assessments measure different substances in their

assessments of dual diagnosis• Split between the mental health and substance

abuse treatment systems impacts dual-diagnosis research

Dual Diagnosis: Methodological Issues in Determining Prevalence Rates cont.

High Rates of Dual Diagnosis

• Exist in community samples– Overall, studies find that a psychiatric diagnosis

yields at least double the risk of a lifetime alcohol or drug use disorder

• Rates of dual diagnosis persist over time• Changes in definitions (DSM-5) will impact

prevalence rates of dual diagnosis in future research

General Psychiatric Patients• Highest rates are among patients with severe mental

illnesses – Bipolar disorder

• 45% have an alcohol use disorder and 39% have a drug use disorder

– Schizophrenia or paranoid disorders• 42% have an alcohol use disorder and 38% have another substance

use disorder

• Other patient groups– Major depression

• 33% have an alcohol use disorder and 18% have a drug use disorder

– Anxiety disorders• 19% have an alcohol use disorder and 11% have another substance

use disorder

Dual Diagnosis: Patients With Primary Substance Use Disorders

• Lifetime and current rates of psychiatric disorders are high (e.g., between 55% and 78%)

• Treatment-seeking substance abusers show high rates of both major depression and bipolar disorder

• Comorbid patients showed greater problems at baseline (more disabled, drank more heavily) than did substance-abuse-only patients– Difference persisted at 3-month follow-up

Dual Diagnosis: Impact on Patient Functioning

• Impacts the severity and course of many disorders, especially among patients with serious mental illnesses – Schizophrenia, bipolar disorder, and recurrent major

depression• More frequent hospitalizations and more relapses

for comorbid substance abusers• Poorer overall life functioning– Social stability – Health quality– Life satisfaction

• Cognitive functioning– Chronic or sustained substance use can contribute to

cognitive impairment and resulting brain dysfunction– Overall, no difference on composite scores of

cognitive functioning exist between individuals with schizophrenia with or without an SUD

– Significantly more work is needed to understand the specifics of cognitive functioning in dual disorders both with regard to preexisting impairment as well as a sequelae of chronic substance use

Dual Diagnosis: Impact on Patient Functioning cont.

• Treatment noncompliance – Substance use often interferes with compliance with both

behavioral and pharmacological treatments– Linked to poorer outcomes

• Violence– Substance use and its associated noncompliance with

treatment is also linked to greater risk for violence – Risk for violent crime among individuals with bipolar

disorder is almost entirely due to substance abuse comorbidity• Those with bipolar-only diagnoses show extremely low risk for

violent crime

Dual Diagnosis: Impact on Patient Functioning cont.

• Suicide– Psychiatric inpatients with major depressive disorder at

greatest risk for suicide– Those with multiple comorbidities are at even higher risk

for suicide than single diagnosis

• Service utilization and health care cost– Increased rate of treatment seeking– Patients with dual diagnoses had psychiatric treatment

costs that were approximately 60% higher than the costs of psychiatrically impaired individuals without substance abuse

Dual Diagnosis: Impact on Patient Functioning cont.

• Physical illness– Individuals with dual diagnosis show increased risk

for HIV and AIDS• People with schizophrenia and other severe mental

illness are now one of the highest-risk groups

– Substance use substantially increases the likelihood of unsafe sex practices and other high-risk behaviors (injection drug use) in those with mental illness

Dual Diagnosis: Impact on Patient Functioning cont.

• Legal problems– While rates of arrest are high, patients are four times

more likely to have encounters with the legal system that do not result in arrest• Continued substance abuse over a long-term follow-up

period was significantly associated with a greater likelihood of arrest

• Homelessness– Patients are more likely to live in an unstable housing

situation or to be homeless– Those with mental illness and substance abuse are more

than 4 times as likely to be homeless than are patients who did not abuse substances

Dual Diagnosis: Impact on Patient Functioning cont.

• Women– Those with comorbid severe mental illness and

substance abuse show: • Poorer retention in treatment • Elevated levels of anxiety, depression, and medical

illness • More difficulty engaging in treatment and are

underrepresented in treatment overall • Higher rates of sexual and physical victimization than

the general population

Dual Diagnosis: Impact on Patient Functioning cont.

• Symptom overlap– Symptoms of many psychiatric disorders overlap

with those of substance use disorders• For example, DSM lists problems in social functioning as

symptoms of both schizophrenia and substance use disorders• Criteria counting toward multiple diagnoses can

potentially increase comorbidity rates and can make a diagnosis of substance abuse difficult

Dual Disorders: Assessment and Diagnosis cont.

• Substance-induced disorders may resemble psychiatric disorders– Because symptoms of substance use and

withdrawal can resemble psychiatric symptoms, differential diagnosis may be confounded

– Incorrect treatment decisions may be made if interventions are aimed at what appear to be acute symptoms of psychiatric disorder but are in fact substance-induced symptoms

Dual Disorders: Assessment and Diagnosis

Interpretation of Psychopathology and Treatment Outcome Research

• The overall result of screening out those with substance use disorders is that there are very few data to inform treatment– Given the significant rates of dual disorders found in

clinical samples, such an omission is clearly problematic

– It is unclear how well findings will generalize to the larger population of individuals with a particular disorder if patients with dual diagnoses are not included

• Solutions involve statistical analyses

Theories of Dual Diagnosis• Common factors models – Some shared influence is responsible for the

development of both psychiatric and substance use disorders (e.g., genetic)

– Twin, adoption, and family studies clearly show that both mental illness and substance abuse run in families

– Studies of familial transmission for comorbid psychiatric and substance use disorders find little evidence for a common genetic factor

– Family history may inspire both dysfunctional family interactions and inheritance of deviant personality traits • Borderline personality disorder and substance use disorders

• Causal models: Secondary substance use disorder models– Self-medication model

• Patients with psychiatric disorders use substances to self-medicate and relieve discomfort associated with the primary psychiatric disorder

– Social facilitation model • Patients with severe mental illness may have fewer

opportunities for social interaction, and substance abuse helps the process of social engagement in patients who lack appropriate social and interpersonal skills

– Neurobiological mechanisms• Neurobiological deficits and abnormalities that provide the basis

for different forms of mental illness may also predispose for substance abuse

• Positive reinforcement

Theories of Dual Diagnosis cont.

• Causal models: Secondary psychiatric disorder models

• Substance abuse causes psychopathology• Substance-induced psychiatric disorder• Chronic alcohol use causes depression, but how?

– Considerable life stress that alcohol dependence promotes for the drinker

– Pharmacological properties of alcohol as a depressant substance

Theories of Dual Diagnosis cont.

• Bidirectional models– Suggest that either psychiatric or substance use

disorders can increase risk and exacerbate the impact of the other

– Alcohol and anxiety interact to produce an exacerbation of both anxiety symptoms and drinking

– Feed-forward cycle • Drinking is promoted by the short-term, anxiety-reducing

effects of alcohol• At the same time, anxiety symptoms are worsened by

heavy drinking, leading to continued drinking in response to these worsened anxiety symptoms

Theories of Dual Diagnosis cont.