Dual Diagnosis Fast Facts

Dual diagnosis is a term for a condition in which a person has a mental health-related issue and a substance use disorder at the same time.

An estimated 17 million Americans had co-occurring mental health-related issues and substance use problems in 2020.

People with a dual diagnosis typically experience more severe symptoms than those diagnosed with a single disorder.

In some cases, substance abuse results from mental health-related issues, as the person uses substances to find relief from the mental health symptoms. In other instances, mental health-related problems may cause the substance use disorder.

Co-occurring mental health-related issues and substance use disorders are often misdiagnosed, and people with a dual diagnosis often don’t get the care they need.

United Brain Association

An estimated 17 million Americans had co-occurring mental health-related issues and substance use problems in 2020.

What is Dual Diagnosis?

Dual diagnosis is a term that refers to the diagnosis of one or more mental health-related issues and one or more substance use disorders in the same person at the same time. These co-occurring disorders are common. Approximately half of the people with a mental health-related issue experience a problem with alcohol or other drugs at some point. The reverse is also true: people with substance abuse problems are at increased risk of mental illness.

Symptoms of Dual Diagnosis

Symptoms vary widely in dual diagnosis cases depending on the mental health-related issues involved and the substances being abused. Symptoms of both the substance use disorder and the mental health-related problems tend to be more severe than in people with only one of the issues.

In general, signs of substance abuse in conjunction with mental health-related issues can include:

  • Retreat from obligations, relationships, and routine activities
  • Abrupt changes in mood or behavior
  • The need for higher and higher doses of the substance to achieve the same effect (tolerance)
  • Withdrawal symptoms when not using the substance
  • Relying on the substance to use to maintain the ability to function in daily routines

What Causes Dual Diagnosis?

In some cases, substance abuse results from mental health-related issues, as the person uses substances to find relief from the symptoms of the mental disorder. In other cases, mental health-related issues may cause the substance use disorder. In still other cases, the cause-and-effect relationship between the disorders is more complex. It is often impossible to tell how or if one condition causes the other, and co-occurring disorders may be coincidental in many cases.

Some possible causal relationships include:

  • Self-medication of mental-health-related issue symptoms may lead to alcohol or drug addiction.
  • Some mental health-related issues alter brain chemistry or function, raising the risk of substance use disorders.
  • Some drugs also alter brain chemistry or function, raising the risk of certain mental health-related issues.
  • External factors such as trauma or stress may cause both mental health-related issues and substance abuse problems at the same time.

Some risk factors increase the likelihood that a given individual will develop substance dependence. These risk factors include:

  • Family history. People who have close relatives who have suffered from alcohol or drug addiction are more likely to develop an addiction themselves.
  • Abuse of other substances. Abuse of alcohol or drugs often increases the likelihood of abuse of other substances.
  • Environmental factors. Trauma, abuse, and other sources of stress make a person more likely to develop substance use disorders, as well as mental health-related issues such as depression or post-traumatic stress disorder (PTSD).

Is Dual Diagnosis Hereditary?

The reasons that people become addicted to alcohol and other drugs are complex. However, scientists have long recognized that there seems to be an inherited genetic component to addiction risk. People who have a drug-addicted parent are at a greater risk of addiction themselves, and studies that have ruled out external influences strongly suggest that the increased risk comes from genes.

However, the exact genetic mechanism that increases addiction risk has not yet been determined. Many genes may be involved, and addiction may stem from a complicated interaction between multiple genes and other factors.

Many mental health-related issues have similarly complex genetic links. For example, people with a family history of schizophrenia are more likely to develop the disorder. The brains of people with schizophrenia have been shown through imaging studies to function differently from healthy brains. These findings suggest that the condition has a genetic component and involves physical dysfunction in the brain.

Post-traumatic stress disorder, a mental health-related issue often linked to substance abuse, may also have an inherited component. Studies have shown that the risk for developing PTSD is strongly connected to genetic predisposition. Studies of twins exposed to the same traumatic situations have suggested that nearly a third of PTSD cases may be explained by genetics.

How Is Dual Diagnosis Detected?

Early detection of co-occurring substance abuse and mental health-related issues is challenging because of the wide variety of possible symptoms and behaviors. In general, warning signs of substance abuse can include:

  • Lethargy or sleepiness
  • Feelings of hopelessness or negativity
  • Anxiety, sadness, irritability, or anger
  • Frequent mood swings
  • Isolation from friends and loved ones
  • Lack of interest in pleasurable activities
  • Unexplained and sudden weight loss
  • Poor hygiene or changes in appearance
  • New, unusual problems at work or school
  • Lying about or hiding their behavior 

How Is Dual Diagnosis Diagnosed?

To determine whether or not a patient has a methamphetamine addiction, a doctor will look for indications that the patient is using the drug, as well as a pattern of use that suggests dependency. Diagnostic steps can include:

  • Blood and laboratory tests. These tests will look for indications that the patient is abusing substances.
  • Medical and psychological history. The doctor will determine whether the patient has a history of substance abuse or mental health-related issues.
  • Family history. The doctor will look for evidence of mental health-related issues and abuse of drugs among the patient’s family members.
  • Psychological evaluation. Mental health professionals can administer exams and assessments to assess the possibility of various mental disorders.

Diagnosis of co-occurring substance use disorders and mental health-related issues is challenging and sometimes controversial. Some doctors and scientists disagree about the causal relationship of the disorders. For example, some believe that co-occurring alcohol or drug abuse is usually the result of an underlying mental health-related issue, and others believe the opposite to be true.

In general, mental illness is thought to be caused by substance abuse only if all of these conditions are true:

  • Mental health-related symptoms only occur during substance use or withdrawal.
  • Symptoms are consistent with those produced by the drug being used.
  • No other condition better explains the symptoms.

Mental health-related issues can be considered distinct from a co-occurring substance use disorder if any of these conditions are true:

  • The mental health-related issue developed before substance use.
  • Symptoms continue even during periods of extended abstinence (more than a month).
  • The symptoms are not consistent with those produced by the substance.
  • The symptoms are not better explained by a disorder or medical condition unrelated to substance abuse.

How Is Dual Diagnosis Treated?

The best course of treatment for dual diagnosis cases involves treating both the substance abuse and all mental health-related issues involved. While it is important that substance abuse be controlled for the treatment of mental disorders to be sustained and effective, mental health professionals no longer believe that treatment of mental health-related issues should be withheld until the substance abuse stops.

Treatment approaches typically use psychotherapy and rehabilitation programs, sometimes combined with medications to treat psychiatric symptoms.

How Does Dual Diagnosis Progress?

The combination of mental health-related issues and substance abuse can produce a long list of long-term complications. The consequences of the co-occurring conditions are often social, legal, and financial. In addition, depending on the drug being used, life-threatening medical issues are also possible.

Some possible long-term effects of dual diagnosis include:

  • Unemployment
  • Homelessness
  • Incarceration or legal difficulties
  • Injury or death from violence or risky behavior
  • Relationship problems
  • Heart disease
  • Liver disease
  • Kidney disease
  • Hallucinations or agitation
  • Seizures
  • Stroke
  • Depression
  • Sexual dysfunction
  • HIV or hepatitis from intravenous drug use
  • Suicide

How Is Dual Diagnosis Prevented?

Because it is difficult (if not impossible) to sort out the factors that result in co-occurring substance abuse and mental health-related issues, finding a way to prevent the disorders from developing together is extremely difficult. Without a reliable preventive strategy, the best course of action is to identify and treat any mental health-related issues as soon as possible. With treatment, the progression of many issues can be slowed or stopped, and the need for self-medication may be lessened.

Dual Diagnosis Caregiver Tips

  • Don’t support abusive behavior. You may be tempted to try to protect your loved one from the consequences of their drug use. However, the insulation you provide can get in the way of their motivation to quit. So instead, be loving and encouraging, but don’t help them get away with the behavior that’s hurting them.
  • Protect yourself. If your loved one is violent or abusive, remove yourself from situations that put you in danger. Take steps, too, to prevent your loved one from exploiting you financially to support their drug use.
  • Find the support you need. Don’t spend all your energy taking care of your loved one without taking care of yourself. Pay attention to your physical health, and get help from a therapist and/or a support group when you need it.

People with dual diagnosis suffer from many different brain-related issues, a condition called co-morbidity. Here are a few of the disorders commonly associated with dual diagnosis:

Dual Diagnosis Brain Science

Many drugs create feelings of euphoria by increasing dopamine levels in the user’s brain. Dopamine is a chemical called a neurotransmitter, a kind of compound that helps the brain’s nerve cells communicate with each other. Dopamine is released when we do something pleasurable–like eat our favorite foods or have sex–so the artificially high level of the dopamine produced by drugs results in an intense good feeling.

The problem is that long-term use of drugs changes how the brain’s nerve cells respond to dopamine, making it more difficult for the user to experience good feelings. Eventually, the drug promotes a rewiring of the brain’s nerve circuitry that prevents parts of the brain from communicating with each other effectively.

It’s this rewiring that causes long-term neurological effects in methamphetamine users, including depression, anxiety, and problems with decision-making, memory, and motor skills. It may take years for the damage to improve even after the user entirely abstains from drug use, and in some cases, the impairments may be permanent.

Dual Diagnosis Research

Title: A Randomized Double-Blind Controlled Trial of Creatine in Female Methamphetamine Users

Stage: Recruiting 

Principal Investigator: Perry Renshaw, MD, PhD, MBA     

University of Utah

Salt Lake City, UT

Methamphetamine (MA) addiction is a public health concern that causes substantial harm to individual users and imposes an economic burden in the U.S., totaling up to $48.3 billion annually. This study proposes addressing a critical aspect of this problem: the lack of proven, FDA-approved pharmacological treatments for MA users. The proposal combines an intervention designed to improve energy metabolism in the brain and a neuroimaging technique capable of measuring the neurochemicals that represent cerebral bioenergetic function. The study will replicate and extend a key neuroimaging finding from the investigators’ recent MA studies: MA users have decreased phosphocreatine (PCr) levels in the brain compared to healthy volunteers. Phosphocreatine is the substrate reservoir for the creatine kinase reaction, which reversibly converts PCr into adenosine triphosphate (ATP), the brain’s primary energy supply, and creatine. Neuronal energy demands are met through a shift in reaction equilibrium, designed to maintain the concentration of ATP constant. Research results from the investigators’ recent study also showed that female MA users have lower brain PCr levels compared to male users. These findings join the converging lines of evidence that MA use is associated with mitochondrial dysfunction, i.e., deficient energy metabolism, in the brain. Frequently, MA users also experience depression, as well as cognitive deficits. Interestingly, both of these entities are also linked to mitochondrial dysfunction in the brain.

The long-term goal of this research program is to define the alterations in brain chemistry that underlie MA use disorders and to utilize translational magnetic resonance spectroscopy (MRS) neuroimaging to identify rational brain-based treatment targets. Once a hypothesis-driven intervention is identified, MRS can then be further employed in treatment studies to verify that “target engagement” is achieved. The specific aims of this proposal are an example of this stepwise scientific process: the nutritional supplement creatine will be tested in a randomized, placebo-controlled study of women with MA use disorders to investigate creatine’s effect on cerebral PCr levels, depressive symptoms, and MA usage.


Title: The Intermittent Oral Naltrexone Enhanced With an Ecological Momentary Intervention Study

Stage: Recruiting 

Principal Investigator: Glenn-Milo Santos, PhD, MPH     

University of California, San Francisco

San Francisco, CA

This is a double-blind, placebo-controlled phase 2b trial in which 150 MSM who use meth will be randomly assigned (2:1) to receive 12 weeks of as-needed intermittent oral naltrexone 50 mg enhanced with an EMA-informed EMI platform or receive as-needed placebo with EMA-informed EMI. The 12-week treatment period is consistent with other pharmacotherapy trials for substance use disorders. The proposed sample size is also consistent with other phase 2b trials for substance use treatment. Upon enrollment, participants will complete daily EMA assessments and weekly visits for behavioral surveys and sweat testing for meth metabolites, study drug dispensing, and counseling for substance use. Safety laboratory assessments and vital signs will be completed monthly. Efficacy (Specific Aims 1-3) will be assessed upon trial completion as measured by proportion meth-positive sweat samples; PrEP and ART adherence by drug levels and viral load testing; and sexual risk behavior data accounting for PrEP use and viral suppression. Long-term treatment effects will be evaluated three months post-treatment.


Title: CRP and S&A for Inpatient Veterans (CRP and S&A)

Stage: Not Yet Recruiting 

Principal Investigator: Elizabeth J. Santa Ana, PhD, MA, BA     

Ralph H. Johnson VA Medical Center

Charleston, SC

The purpose of this study is to evaluate how well three types of treatments work to improve the outcomes for people with substance use problems. Veterans admitted to the Charleston VA Psychiatric inpatient unit may be invited to participate. The three types of treatments that will be evaluated are:

  • Combined Recovery Program (CRP), a six-session treatment group delivered on the inpatient unit.
  • A Home Telehealth program, called Stable and Able (S&A), provided just prior to discharge and offers additional support for up to 3 months
  • Treatment-as-usual (TAU), which is the treatment currently provided on the unit, consisting of various mental health topics and sessions designed to help with recovery.

Participation begins on the inpatient unit, beginning with CRP and/or TAU, and may continue with S&A post-discharge. Participants will be followed up at 1 and 3- months post-treatment.

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