Drug Use and and Co-occurring Disorders – How are They Linked?

The Connection Between Mental Illness and Substance Abuse

Co-occurring disorders (COD) refers to a medical condition. This is where a patient has both a mental health disorder as well as problems with drug abuse. They also call it dual disorders.

Drug use and co-occurring disorders often happen in many patients. Drug use can be a cause of a mental disorder. On the other hand, the latter may happen due to the drug abuse. For example, a person struggling with depression may abuse alcohol. Similarly, a heroin addict may develop major depression over prolonged abuse.

In many cases, it’s not possible to know if mental illness is the cause or effect of drug abuse. The overall health and economic burden of this complex combination are greater than those of the single disorder.

Co-occurring Disorders: A Complex Association between Mental Illness and Drug Use

Approximately 7.9 million American adults had co-occurring disorders in the same year. This is according to a 2014 survey report by Substance Abuse and Mental Health Services Administration (SAMHSA).

Note: The American Psychological Association (APA) says more than 8.9 million persons have co-occurring disorders.

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How Can Addiction Cause Mental Illness?

Addiction itself is a mental illness. As a result, it can lead to a number of other psychiatric problems. They range from mood disorders such as anxiety and depression to severe mental health problems including psychosis.

Here are some ways how drug use can cause a mental illness:

  • Drugs can alter the chemistry of the brain. Some of them cause excitation while some cause an inhibition of brain activity. Over a prolonged period, drug abuse can cause permanent changes in the brain chemistry. The type of mental illness an individual may suffer after chronic drug use depends on the specific brain chemical. Furthermore, they also depend on the brain area affected.
  • Addiction can bring about mental illness in people who are prone to mental illness, environmentally or genetically.

How Can Mental Illness Trigger Drug Use?

In some patients with co-occurring disorders, drug abuse could be the cause. It is because the person used the drug as an escape. For instance, an individual with depression or anxiety can start with medications or alcohol to ease the symptoms. Over time, a continuous use of the drug can turn into an addiction.

Drug Use and Co-occurring disorders: What Do Stats Say?

Approximately 20% and 18% of current drug abusers had at least one mood disorder and one anxiety disorder respectively. This is according to a study conducted by the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC).

What Are The Most Common Co-occurring Disorders?

An individual who abuses either alcohol or drug (or both) may have more than one co-occurring disorders.

Mental health problems that are prevalent in drug abusers include:

  • Depression
  • Bipolar Disorder
  • Anxiety Disorders
  • Schizophrenia
  • Antisocial Personality Disorder (APD)

What are Treatment Approaches for Drug Use and Co-occurring Disorders?

Treating co-occurring disorders is essentially a tougher task for the healthcare professionals. This is due to the complexity of the condition. Therefore, an optimum treatment program should address both the mental illness and drug addiction at the same time.

For effective treatment of co-occurring disorders, many clinicians prefer to use “disease models”. They attempt to discover the complex relationship between drug use and co-occurring disorders.

  • Drug use as the Cause for Co-occurring Disorders: This model puts drug use as the driver for mental illnesses. Understandably, they focus the treatment approaches towards treating the causative drug abuse problems.
  • Self-medication Model: This disease model arguably recognizes co-occurring mental illnesses as the reason behind the patient’s drinking and drug use. They also call it “Primary co-occurring disorder and secondary substance use disorder” model. They direct core treatment towards treating the underlying mental health issues.
  • Shared Pathway: With this model, a combination of genetic and environmental factors can cause both drug use and co-occurring disorders, simultaneously.

How To Know If Co-occurring Disorders is Primary or Secondary?

Do you need help in differentiating whether co-occurring disorders is primary or secondary? The DSM-IV-TR (American Psychiatric Association 2000) has given certain guidelines for that. Consider the co-occurring disorders primary if

  • You started abusing drug after the diagnosis of one or more mental illnesses.
  • The symptoms of mental illness do not correspond to the ones characteristic to the abused substance. For example, developing hallucinations after opioid withdrawal.
  • The symptoms linger for long periods after you stopped taking the drugs.
  • Consider the mental disorder secondary if
    • You started experiencing the symptoms of mental illness during drug abuse or within 30 days after stopping the drug.
    • Symptoms correspond to the ones characteristic to the abused substance

Note: The above-mentioned guidelines are meant for informational purpose only. You should not use it as a guide for self-diagnosis of co-occurring disorders. If you experience any mental health issue, before or after drug use, you should talk to your doctor right away.


  • Drug use and co-occurring disorders are more complicated and require extra efforts to control and cure.
  • Co-occurring disorders are more common than previously thought. Hence, you need to follow the proper diagnosis and treatment guidelines.
  • Integral treatments for drug use and co-occurring disorders include a combination of behavioral therapy, medications and support groups.
  • They recognize increasing age, poor financial condition and living in cities as risk factors for drug use and co-occurring disorders.

Want to Know More?

Do you have any questions or queries about drug use and co-occurring disorders? You should talk to the experts to get accurate information.

For more on drug abuse, addiction, available treatments, and additional suggestions, click here. It will connect with the best addiction centers near you.

Drug Use and and Co-occurring Disorders – How are They Linked?

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