Behavioral Health

Caring for patients with co-occurring mental health & substance use disorders

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Consider substance abuse if Tx for mood or anxiety disorders is ineffective. Don’t defer treating a mental health issue until a substance use disorder is resolved.




Janice J* visits her family physician with complaints of chest pain, shortness of breath, and heart palpitations that are usually worse at night. Her medical history is significant for deep vein thrombosis secondary to an underlying hypercoagulability condition (rheumatoid arthritis) diagnosed 2 months earlier. She also has a history of opioid use disorder and has been on buprenorphine/naloxone therapy for 3 years. Her family medical history is unremarkable. She works full-time and lives with her 8-year-old son. On physical exam, she appears anxious; her cardiac and pulmonary exams are normal. A completed workup rules out cardiac or pulmonary problems.

  • What is your diagnosis?
  • How would you treat this patient?

* The patient’s name has been changed to protect her identity.


Co-occurring disorders, previously called “dual diagnosis,” refers to the coexistence of a mental health disorder and a substance use disorder. The obsolete term, dual diagnosis, specified the presence of 2 co-occurring Axis I diagnoses or the presence of an Axis I diagnosis and an Axis II diagnosis (such as mental disability). The change in nomenclature more precisely describes the co-existing mental health and substance use disorders.

Currently the Diagnostic and Statistical Manual of Mental Disorders, 5th edition, (DSM-5) includes no diagnostic criteria for this dual condition.1 The criteria for mental health disorders and for substance use disorders comprise separate lists. Criteria for substance use disorder fall broadly into categories of “impaired [self] control, social impairment, risky behaviors, increased tolerance, and withdrawal symptoms.”1 It is estimated that 8.5 million US adults have co-occurring disorders, per the 2017 National Survey on Drug Use and Health conducted by the Substance Abuse and Mental Health Services Administration.2 Distinguishing which of the 2 conditions occurred first can be challenging. It has been suggested that the lifetime prevalence of a mental health disorder with a coexisting substance use disorder is greater than 40%3,4 (TABLE 11,4-8). For patients with schizophrenia and bipolar disorder, these numbers may be higher.

Table of US prevalence of mental health disorders and their association with co-occurring substance use disorder

The consequences of undiagnosed and untreated co-occurring disorders include poor medication adherence, physical comorbidities (and decreased overall health), diminished self-care, increased suicide risk or aggression, increased risky sexual behavior, and possible incarceration.9


With some patients, only one diagnosis may be apparent at a given point, which could make it difficult to expeditiously recognize the onset of a co-occurring condition. For example, if a patient with anxiety has been treated successfully for years and then experiences a worsening of symptoms, it’s possible a physician might increase the dosage of anxiety medication without reevaluating for a substance use disorder. However, when both co-occurring disorders are present, the patient usually exhibits a greater number of symptoms and, if the full scope of the condition remains unrecognized, will likely respond poorly to therapy and have a prolonged course to resolution.3,8-13 Consider a co-occurring substance use disorder if treatment resistance persists, or if a patient has a recurrence or an exacerbation of a previously well-treated psychiatric disorder.

The estimated lifetime prevalence of coexisting mental health and substance use disorders is > 40%.

Diagnosing a second condition can also be difficult when a patient’s symptoms are actually adverse effects of substances or prescribed medications. For example, a patient with worsening anxiety may also exhibit increasing blood pressure resistant to treatment. The cause of the patient’s fluctuating blood pressures may actually be the result of his or her use of alcohol to self-treat the anxiety. In addition to self-medication, other underlying factors may be at play, including genetic vulnerability, environment, and lifestyle.14 In the case we present, the patient’s conditions arose independently.

Anxiety disorders, with a lifetime risk of 28.8% in the US population,4 may be the primary mental health issue in many patients with co-occurring disorders, but this cannot be assumed in lieu of a complete workup.2,8,9,15 Substance use disorders in the general population have a past-year and lifetime prevalence of 14.6%.1,4,16,17 Because the causal and temporal association between anxiety and substance abuse is not always clear, it’s important to separate the diagnoses of the mental health and substance use disorders.



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