What is Dual Diagnosis

What is Dual Diagnosis

Authored by Jane Squire MSc

Reviewed by Michael Por, MD

Dual diagnosis (also known as simultaneous or co-occurring disorders) is a term when a mental illness and a substance use disorder occur simultaneously. However any disorder – substance use or mental illness – can develop first. Mental Health complexities such as depression may lead to substance abuse and conversely substance abuse may cause mental health issues to manifest and develop such as schizophrenia, paranoia and anxiety.1https://www.nami.org/About-Mental-Illness/Common-with-Mental-Illness/Substance-Use-Disorders

People with mental illness may turn to alcohol or other drugs as self-medication to improve mental health symptoms. However, research shows that alcohol and other drugs worsen the symptoms of mental illness.

The occupational fields of mental health and the substance treatment are often polar opposites in terms of treatment modalities so it can often be difficult to find a treatment facility or rehab specialized in integrated care.2https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2880934/

How common is dual diagnosis?


According to the National Drug Use and Health Survey, 9.2 million U.S. adults had both mental illness and substance use disorder last year. Since many combinations of double diagnoses can occur, the symptoms are very different. A number of years ago psychiatric clinics began using alcohol and drug screening tools to identify people at risk of drug and alcohol abuse.

The symptoms of a substance disorder can be:


  • Retreat from friends and family
  • Sudden changes in
  • behavior
  • Use of substances under dangerous conditions
  • Risky behavior
  • Loss of control over the use of substances
  • Development of a high tolerance and withdrawal symptoms
  • Feel like you need medication to work


The symptoms of a mental illness can also be very different, with warning signals including:


  • Extreme mood swings
  • Confused thinking
  • Problems concentrating
  • Avoiding friends
  • Avoiding social activities
  • Suicidal thoughts


How is dual diagnosis treated?


According to the The Substance Abuse and Mental Health Services Administration, the best treatment for dual diagnosis is integrated intervention when a person is cared for both for their diagnosed mental illness and for drug abuse by the same team at the same time. Dual Diagnosis issues can make recovery from addiction harder and until they are addressed, they will function as endless prompts to chronic relapse.

You and your practitioner should understand how each disease affects the other and how your treatment can be most effective. Treatment planning is not the same for everyone, but the following are the common methods used in the treatment plan:

The first big hurdle that people with double diagnosis have to overcome is detoxification:


1. Inpatient detoxification is usually more effective than outpatient detoxification for reasons of sobriety and safety. During inpatient detoxification, trained medical personnel monitor a person around the clock for up to seven days. The staff can administer tapered amounts of the substance or its medical alternative to wean a person and reduce the effects of the withdrawal. Some of our Featured Rehabs have their own inpatient medial detox facility while others prefer to work with local private hospitals.

2. World Class Inpatient rehabilitation. A person suffering from a mental illness and having dangerous and / or dependent patterns of substance use can benefit from an inpatient rehabilitation center where they can receive medical and psychological care around the clock. These treatment centers offer therapy, support, medication and health services to treat substance use disorder and its underlying causes.

3. Luxury sober housing, like group houses or sober houses, is an inpatient treatment center that can help people who are newly sober or who are trying to avoid relapse. These centers offer support and independence. Sober houses have been criticized for offering different levels of care quality as they are generally not managed by licensed professionals.

4. Psychotherapy is usually an important part of an effective treatment plan with double diagnosis. Cognitive behavioral therapy (CBT) in particular helps people with double diagnosis to deal with and change ineffective thought patterns, which can increase the risk of substance use.

5. Medications are useful for treating mental illness and certain medications can also help people with substance use disorders to alleviate the withdrawal symptoms during the detoxification process and promote recovery.

What is the difference between comorbidity and dual diagnosis?


Dual Diagnosis is a medial term listed in DSM 51 and used to describe a person suffering from both a mental health disorder and substance abuse at the same time. Dual Diagnosis is also known medically as as co-occurring disorders or comorbidity.

The phrase  “comorbidity” describes two or more mental health disorders occurring in the same person. Technically, according to DSM-5, a person can receive more than one personality disorder diagnosis. Indeed, it is often the case that people who are diagnosed with a personality disorder may also meet the criteria for multiple manifestations hence the term multiple personality disorder.

Dual Diagnosis Statistics


The lifetime prevalence of a dual diagnosis is:


  • 47% for people with schizophrenia
  • 56% for those struggling with bipolar disorder
  • 78% for people seeking treatment for drug problems


Six percent of people admitted to hospital in a psychiatric treatment center in 2019 were diagnosed with a dual diagnosis of alcohol-free drug use disorder, 4% with alcohol-use disorder, and 4% with alcohol and other drugs.

Mental illnesses can be associated with certain specific substances and the effects of various substances tend to interact with certain mental health problems in a semi-predictable manner. Often, the effects of a particular substance being abused counteract the symptoms of the corresponding psychological state – for example, relaxing medications are used more often by people with anxiety disorders.

Substance misuse and mental health issues


Drug abuse problems are commonly related to a specific group of mental health problems, including:


  • Anxiety disorders
  • Personality disorder
  • Post-traumatic stress disorder (PTSD)
  • Eating disorders (e.g. anorexia nervosa, bulimia nervosa)
  • Schizophrenia
  • Antisocial personality disorder


60-80% of those diagnosed with antisocial personality disorder were found to have alcoholism, and 20-40% of those diagnosed with alcoholism were also diagnosed with antisocial personality disorder.3https://www.sciencedirect.com/science/article/abs/pii/S0006322304007395

People who have been diagnosed with schizophrenia are more likely to use stimulants (such as nicotine, amphetamines, cocaine, and marijuana), although it is often unclear whether the mental disorder or drug abuse occurred first.

Alcohol misuse is also linked to depression and anxiety.4https://en.wikipedia.org/wiki/Dual_diagnosis One study found that people who were diagnosed with alcohol consumption disorder were 4 times more likely to suffer from depression and 3 times more likely to experience anxiety disorders.

The mental disorder most related to substance abuse is bipolar disorder. Some estimates assume a lifetime prevalence of 50-60%. This means that the likelihood that substance use and bipolar disorder will occur together is 50 to 60%.5https://www.sciencedirect.com/science/article/abs/pii/S1476179307001383

Can substance misuse be confused with mental disorder?


Sometimes drug abuse looks like a mental disorder because substance use and abuse can cause symptoms that are otherwise associated with organic mental health problems. These symptoms differ somewhat from those of an independent mental disorder itself, as they are a direct result of substance use and can usually be treated more quickly by discontinuing the substance.

These symptoms may be related to a specific pattern of abuse, poisoning effects of, and a withdrawal syndrome associated with the substance. Examples include:

  • Methamphetamine-induced psychosis or mania.
  • Severe anxiety due to withdrawal of benzodiazepines.
  • Depression due to discontinuation of stimulants.
  • Korsakoff syndrome (memory and cognitive problems) due to chronic alcohol abuse.


References: What is Dual Diagnosis

1. Drake R, Mercer-McFadden C, Mueser K, et al. Review of integrated mental health and substance misuse treatment for patients with dual diagnosis. Integrated Mental Health and Substance Abuse. 1998;24(4):589–605. [PubMed] []

2. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision. Washington, DC: American Psychiatric Press, Inc; 2002. []

3. Tiet Q, Mausbach B. Treatments for patients with dual diagnosis: A review. Alcohol Clin Exp Res. 2007;31(4):513–36. [PubMed] []

4. Cuffel B, Shumway M, Chouljian T, MacDonald T. A longitudinal study of substance use and community violence in schizophrenia. J Nerv Ment Dis. 1994;182:704–8. [PubMed] []

5. Ridgely M, Goldman H, Willenbring M. Barriers to the care of persons with dual diagnosis. Schizophr Bull. 1990;16(1):123–32. [PubMed] []

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What is Dual Diagnosis
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What is Dual Diagnosis
Dual diagnosis is a term when a mental illness and a substance use disorder occur simultaneously. Mental Health complexities such as depression may lead to substance abuse and conversely substance abuse may cause mental health issues to manifest and develop such as schizophrenia, paranoia and anxiety.
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