The Importance of Treating Co-Occurring Disorders Together

In recent years, destigmatization campaigns across the country have called attention to the prevalence of mental health disorders, reminding us that one in five of us will experience a clinical mental illness in our lifetime, that 1.5% of us have anxiety in any given year, and that more than 300 million people around the globe have depression. But while these statistics can be comforting in a way and help break through the isolation many people feel, they don’t tell the full story.

In reality, psychiatric distress is often not the result of a single diagnosis, but the product of multiple disorders occurring simultaneously, fuelling each other, and augmenting your suffering. The American Psychology Association estimates that 45% of people living with mental illness meet the diagnostic criteria for two or more disorders. People with a mental illness are also twice as likely than the general population to struggle with addiction and “at least 20% of people with a mental illness have a co-occurring substance use problem.” Similarly, those struggling with eating disorders often exhibit symptoms of another mental health disorder and may also engage in harmful substance use. The unique suffering of people with multiple disorders is unfortunately often not captured in popular discourses surrounding mental illness, leaving many to feel alone, lost, and without hope.

The reasons for high co-occurrence rates are complex and not fully understood. However, there are two primary hypotheses backed by a growing body of scientific evidence: shared genes and shared neurology.

Shared Genetics

The genes that predispose you to developing one mental health disorder could also predispose you to developing another mental health disorder or a substance use disorder. According to emerging research, genetics are responsible for approximately 40-60% of a person’s likelihood of developing a substance abuse disorder. As the National Institute on Drug Abuse explains, “Genes [can alter] how an individual responds to stress or [increase] the likelihood of risk-taking and novelty-seeking behaviors, which could influence the development of drug use disorders and other mental illnesses.”

Shared Neurology

Mental health disorders and addictions involve the same or similar regions and activities of the brain, including neurotransmitter behavior. While this could mean that disparate disorders develop due to the same abnormalities, researchers also believe that brain changes caused by one disorder may be directly responsible for the development of another. “For example, drug abuse that precedes the first symptoms of a mental illness may produce changes in brain structure and function that kindle an underlying propensity to develop that mental illness.” Similarly, a mental illness could produce brain changes that “increase the vulnerability to abusing substances by enhancing their positive effects, or alleviating the unpleasant effects associated with the mental disorder or medication used to treat it,” also known as self-medication.

Co-occurring disorders present unique conditions for suffering that are qualitatively different than those resulting from a single disorder and significantly increase relapse risk. As explained in Psychology Today:

People with co-occurring disorders often experience more severe and chronic medical, social, and emotional problems than people experiencing a mental health condition or substance use disorder alone. Compared to patients who have a single disorder, patients with co-existing conditions often require longer treatment, have more crises, and progress more gradually in treatment.

The complex and interrelated nature of co-occurring disorders means that treatment models targeting only one diagnosis at a time are based in a fundamentally flawed understanding of co-occurrence as two or more ailments occurring in isolation from each other. In fact, they are deeply intertwined and must be treated as such. “Extensive research has documented the need to treat all conditions from which a patient suffers,” write Sterling, Chi, and Hinman. “Moreover, a growing body of research suggests integrated approaches to treatment may improve the outcomes of people with [substance abuse] problems.” If your process addiction is treated without addressing your schizophrenia, your chance of relapse increases exponentially. Similarly, if your depression is treated without addressing your anxiety, you are left not only struggling with the remaining disorder, but likely to find your uncontrolled anxiety triggering a new depressive episode.

But the growing body of research helping us understand why disorders so frequently occur together is also elucidating how this knowledge can be leveraged to improve treatment. By treating co-occurring disorders together, you can explore the shared roots of your illnesses and participate in pharmacological and behavioral interventions to find relief from your full range of symptoms. In doing so, you are able to disrupt the feedback loop that so frequently fuels multiple disorders, gaining the knowledge and skills you need to encourage neurological equilibrium and managing triggers that threaten your stability.