Published May 31, 2016
Are people with mental illness more likely to abuse drugs? Or does abusing drugs contribute to mental illness?
This is the “chicken or the egg” question faced by many professionals who treat people with the dual diagnosis of addiction and mental illness. There is no easy answer. The two issues can be intertwined for many reasons. However, understanding the nature of dual diagnosis is key in ensuring patients receive the proper treatment.
The American Psychiatric Association defines a number of mental disorders, including substance-related and addictive disorders, in its Diagnostic and Statistical Manual of Mental Disorders, which is considered the authority for the classification and diagnosis of mental illnesses and conditions.
Mental health disorders exist along a broad spectrum of conditions and symptoms. The most common mental health disorders are anxiety and depression. These disorders impair day-to-day functioning, and are more severe and last longer than the feelings of anxiousness and sadness that everyone experiences. Less common, but more severe mental illnesses include bipolar disorder, schizophrenia and trauma-related disorders such as PTSD. Treatment for mental disorders can include psychotherapy, support services and/or medication, depending on the specific disorder and its severity.
According to the National Institute on Drug Abuse (NIDA), as
many as six in 10 people who have a substance use disorder also
experience a mental disorder at some point in their lifetime.
Within the field of psychiatry, when two or more disorders coexist
in the same person, they are referred to as
“co-occurring” or “comorbid.”
A variety of factors account for the high level of co-occurrence of substance use and mental disorders. The “chicken or the egg” issue is part of the problem—drug abuse may initiate the onset or increase the severity of other mental illnesses, or mental disorders may lead to drug use and abuse, as people attempt to “self-medicate” to cope with their symptoms.
Other issues that influence risk for co-occurrence include:
People have long believed certain mental illnesses or substance use disorders “run in the family.” Researchers are finding increasing evidence indicating that genetic factors are, in fact, an important cause of this familial pattern predisposing particular people to psychiatric problems, substance abuse or both.
Recent research suggests that roughly 50 percent of a person’s vulnerability to addiction is attributable to genetics, according to NIDA. Genetics also contribute to mental illness. A 2013 study by the National Institute on Mental Illness (NIMH) found that five mental disorders—autism, ADHD, bipolar disorder, major depression and schizophrenia—shared a number of common genes. Many of these genetic vulnerabilities also are related to addiction and may influence the co-occurrence of these disorders.
Researchers also are examining neurotransmitters in the brain and their involvement in both addiction and psychiatric disorders. For example, the neurotransmitter dopamine plays a role in how the brain is affected by addictive substances, as well as in the development of certain mental illnesses such as depression and schizophrenia.
Children exposed to drugs, alcohol or tobacco in the womb exhibit neurological changes that can increase the risk for behavioral issues, mental health issues and addiction. In a similar fashion, early use of substances can contribute to neurological changes which then influence continued use.
Environmental factors, including stress, also are shared risks
that can contribute to the predisposition to substance use
disorders, mental illness or both. Individuals who have experienced
physical or psychological trauma in youth or adulthood may turn
to substance use as a coping mechanism, or trauma may trigger
mental illness in people who already have genetic
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The high rate of co-occurrence of substance abuse and mental illness has prompted NIDA to advocate that all patients who are admitted for or seek treatment for psychiatric illnesses are screened for substance use disorders, and people who seek substance abuse treatment be evaluated for mental health issues. Unfortunately, this does not always occur.
A 2014 study by the Substance Abuse and Mental Health Services Administration (SAMSHA) found that nearly 8 million Americans had co-occurring disorders. However, only 7.4 percent of those affected received treatment for both problems; more than 55 percent received no treatment for either addiction or the other mental disorders.
A number of barriers exist when identifying co-existing mental health and substance abuse conditions. Unfortunately in the U.S., different health care systems are in place to address the two problems. Mental health issues are typically treated through the medical establishment, while substance abuse problems are typically addressed via a variety of other treatment channels, such as social services, public or private clinics and counseling.
In addition, there has sometimes been reluctance by substance
abuse treatment practitioners to introduce any type of medication
for fear of further dependence. However, certain medications may be
critical to treating mental illness. Unfortunately, practitioners
in substance abuse settings may not have the training to address
the variety and complexity of mental disorders observed in their
Conversely, practitioners who treat mental illness sometimes lack the training to evaluate and address substance abuse in their patients. Inadequate treatment can have serious repercussions. Those who do not receive treatment for co-occurring disorders are more likely to experience legal problems, homelessness, suicide and death.
After the appropriate diagnosis of co-occurring mental illness and substance use disorders, a variety of treatment options exist. Recent consensus suggests that comorbid conditions be treated concurrently—that is, practitioners should not wait until an addiction is successfully addressed before treating psychiatric problems, and vice versa.
Behavioral therapies, alone or in combination with medication, have been found to be effective strategies for treating both mental health and substance use disorders. For example, taking part in behavioral therapy will enhance skills that help to relieve stress and avoid situations that may result in a relapse. The therapy aims to transform unhealthy thinking by using conscious thoughts to challenge beliefs and change potentially dysfunctional behaviors.
The type of treatment a person receives should take into consideration the type and severity of the mental illness in addition to the nature of the person’s addiction. Parts Two and Three of this Expert Summary Series will explore in-depth the various options available for depression and anxiety, as well as for those with more severe mental illnesses and drug addictions.