Co-Occurring Disorders: Mental Illness and Substance Abuse

Mental health disorders and substance use disorders are common health issues. When these conditions co-occur, it can increase the severity of both conditions.

When a person is diagnosed with both a mental illness and a substance use disorder, they are said to have co-occurring disorders. Though the disorders can exist separately from one another, when they coexist in the same person, they usually cause the symptoms of both disorders to be amplified. It is common for a person with co-occurring disorders to have more severe symptoms than a person with only one of the disorders.

What Are Co-Occurring Disorders?

A co-occurring disorder is defined by the dual diagnosis of a mental health disorder and a substance use disorder in the same person. These diagnoses can be made at the same time, or they can be made one after the other, but the two disorders occur simultaneously in the same person.

Symptoms of Co-Occurring Disorders

Only a mental health professional can diagnose a mental health or substance use disorder. However, knowing the common symptoms of co-occurring disorders may help an individual recognize when they need assistance. The symptoms of co-occurring disorders are similar to the symptoms of mental health and substance use disorders, but they occur in the same person. Those symptoms include:

• Retreating from relationships with family and friends
• Sudden changes in behavior
• Difficulty managing daily tasks
• Engaging in risky behaviors
• Neglecting health and hygiene
• Using substances under unsafe conditions
• Losing control over substance use
• Developing a high tolerance to a substance or withdrawal symptoms
• Feeling the need to use substances to function normally

Mental Disorders that Co-Occur with Substance Abuse

There are several different kinds of mental health disorders that commonly co-occur with substance use disorders. The most common co-occurring disorders with substance abuse fall into five categories:

1. Mood disorders
2. Anxiety disorders
3. Psychotic disorders
4. Personality disorders
5. Eating disorders

While there are differences among them, many of them have similar attributes as to how they are diagnosed, what causes them to co-occur and how the two disorders affect one another. Examples of co-occurring disorders include:

Mood Disorders

Mood disorders are characterized by disruptions in mood that affect a person’s life, such as major depressive disorder and bipolar disorder. Mood disorders and substance abuse disorders are commonly co-diagnosed. It is unclear which disorder is more commonly diagnosed first in patients that have both, but it is clear that one has an effect on the other.

In many cases, patients with co-occurring substance use and mood disorders have more severe symptoms than either disorder alone. It is common to try and treat a substance use disorder first and then address the mood disorder. However, studieshave shown that treating both conditions simultaneously improves patient outcomes.

Anxiety Disorders

Anxiety disorders include generalized anxiety disorder, social anxiety disorder, obsessive-compulsive disorder and post-traumatic stress disorder. Anxiety and substance abuse are also commonly diagnosed and are among the most common co-occurring disorders.

As is the case with mood disorders, substance abuse and anxiety disorders tend to be more severe in a person that is co-diagnosed than a person that has either one of the disorders alone. However, it is less common for anxiety disorders to be substance-induced than mood disorders. People with anxiety disorders may use substances to self-medicate and relieve their anxiety symptoms, which can lead to substance abuse.

Psychotic Disorders

Psychotic disorders involve changes in the way a person thinks and perceives themselves, others and their environment. Examples of psychotic disorders include schizophrenia, delusional disorder and schizoaffective disorder. A common symptom among psychotic disorders is psychosis, which is a temporary state where a person experiences hallucinations or delusions.

Psychotic disorders and substance abuse disorders can be hard to co-diagnose because psychosis can sometimes be a symptom of substance abuse. Drug-induced psychosis occurs when a person taking a substance experiences temporary hallucinations or delusions. Withdrawal from certain substances can also have psychotic effects. To be co-diagnosed, psychotic symptoms must also be present in the absence of substance use.

Schizophrenia and substance abuse, in particular, are commonly co-diagnosed. Substance use can make schizophrenia symptoms significantly worse. The underlying genetic conditions that increase a person’s risk of developing schizophrenia can also make a person vulnerable to a substance use disorder. Because of genetic predisposition, substance use may start early in life, causing the person to be more at risk for developing a substance use disorder.

Personality Disorders

Personality disorders cause people to have unhealthy thoughts and behaviors that affect their everyday life and relationships. Common personality disorders that co-occur with substance use disorders include borderline personality disorder, antisocial personality disorder and narcissistic personality disorder, with the most common being borderline and antisocial personality disorders.

Personality disorders and substance abuse disorders are more commonly co-diagnosed in people with drug use disorders rather than alcohol use disorders. The high prevalence of co-diagnosis is usually a result of a personality disorder being followed by a substance use disorder.

Eating Disorders

Eating disorders are characterized by dysfunctional eating habits. Examples of eating disorders include binge eating disorder, anorexia nervosa and bulimia nervosa. People with bulimia nervosa or anorexia nervosa with binge eating and purging habits tend to be at a higher risk of substance use than individuals other types of eating disorders.

In general, eating disorders and substance abuse are commonly co-diagnosed. Studies have suggested that a genetic link could be the cause. Genetic factors that make a person more liable to eating disorders are also found among those that make a person liable to substance use disorders.

How Common Are Co-Occurring Disorders?

Co-occurring disorders are quite common. Co-occurring disorders were diagnosed in an estimated 8.5 million adults in the United States in 2017. Of those 8.5 million adults, nearly 51% received treatment for either their substance use disorder or their mental health disorder. Only 8.3% received treatment for both disorders.

Risk Factors and Causes of Co-Occurring Disorders

There are many common risk factors, that may make a person more susceptible to being diagnosed with co-occurring disorders. Some of the underlying conditions that might make a person susceptible to co-occurring disorders include:

• Genetics
• Family history
• Environmental influences
• Stress and response to stress
• History of trauma or adverse childhood experiences

Which Comes First: Addiction or Mental Illness?

A person with a dual diagnosis of drug addiction and mental illness could develop either condition first. There is not a standard order in which the disorders are generally diagnosed. While it is unclear which usually develops first, mental illness and addiction often influence one another.

Underlying Mental Illness as a Cause of Addiction

Mental illness may contribute to addiction when a person uses a substance to self-medicate. As a result, the person comes to rely on the substance to feel normal. This may lead to needing more and more of the substance to feel its effects and, eventually, developing an addiction to the substance as a result.

A person with a mental health issue may also have changes in their brain functioningthat makes them more susceptible to a substance use disorder. The changes in brain signaling pathways may make a person crave a drug more, making them more likely to become addicted to it.

Effects of Substance Abuse on Mental Health Issues

When a person who has a mental health issue also uses a substance that affects their state of mind, it can have an impact on their underlying mental health. In most cases, drug use affects mental health by making the symptoms of the mental health disorder worse.

Additionally, there are several other consequences that substance abuse can have on mental health issues. People who have a substance use disorder are also less likely to adhere to the medication for their mental health disorder, making it difficult to get their mental health disorder symptoms under control. Substance use disorders are also associated with an increase in aggressive and violent behavior.

Diagnosing Co-Occurring Disorders

Mental health and substance use disorders are diagnosed according to defined criteria in the Diagnostic and Statistical Manual of Mental Disorders (DSM). This manual acts as a handbook for clinicians to diagnose specific mental health or substance use disorders based on symptoms that commonly occur. While there are clear definitions for mental health issues and substance abuse issues, the manual previously lacked descriptions of co-occurring disorders.

This improved in the fifth edition of the manual, the DSM-5, which was updated to better define co-occurring substance use and mental health disorders. It recognized that a person with a co-occurring disorder will usually have the same mental health symptoms as a person who has a mental health disorder but does not have a substance use disorder. It also takes into consideration that the substance use disorder is not necessarily worse in a person with a mental health disorder. Basically, the person will exhibit symptoms of both disorders.

Dual Diagnosis Treatment Options for Co-Occurring Disorders

When considering the treatment of co-occurring disorders, it is important to address both disorders. Dual diagnosis treatment will provide the patient with a means to control their substance use disorder while also providing the resources necessary to relieve the symptoms of their mental health disorder.

An integrated treatment program for co-occurring disorders addresses a client’s substance use disorder while providing them with therapy for their mental health conditions. Once the person has control of their substance use disorder, medication may also be added to their treatment program that will help with their mental health condition. It is common to wait for the patient to stop substance use prior to initiating medication due to the side effects of mixing mental health medication with substances that are commonly abused.

Continuing Research and Outlook

While the co-occurrence of substance use disorders and mental health disorders has long been observed, treatment for the two disorders simultaneously has only more recently been developed. It is still relatively common for the two disorders to be treated separately rather than together. It is also common to address the substance use disorder prior to treating the mental health disorder. However, dual diagnosis research studies show that there is a benefit to simultaneously treating both disorders to achieve better outcomes for the patient.

Developing treatment plans for co-occurring disorders is challenging for many reasons. The specific type of treatment needed varies depending on the type of mental health disorder and substance use disorder. More individualized research is needed to understand the link between specific mental health conditions and addiction. Dual diagnosis case studies will help to determine treatment outcomes in individuals with specific co-occurring disorders.

If you or a loved one are struggling with a mental health disorder and a substance use disorder, The Recovery Village can help. The Recovery Village has dual diagnosis treatment programs that can address both diagnoses. To learn more about our comprehensive treatment plans, call The Recovery Village to speak with a representative.

Editor – Megan Hull

Megan Hull is a content specialist who edits, writes and ideates content to help people find recovery. Read more

Medically Reviewed By – Dr. Trisha Sippel, PhD

Dr. Sippel is a diversely trained scientist with expertise in cancer biology and immunology. Read more