Co-occurring Disorders: Link Between Mental Health and Addiction

January 2, 2020 | 11:43 am | , Leave your thoughts

It is not uncommon for a loved one to enter treatment for an alcohol use disorder to soon after, be diagnosed with depression.

Although their first presenting and most dangerous symptoms were associated with their high alcohol consumption, their alcohol use disorder could have been a coping mechanism to deal with their underlying undiagnosed depression.

Co-occurring disorders are tricky, and many loved ones are surprised to discover that although their family member is in treatment for an addiction, the underlying mental health disorder was what fueled this addiction in the first place.

Their undiagnosed depression has been hiding in the shadows ever since the beginning of their drug or alcohol use.

The term co-occurring disorder refers to both a mental health condition and a substance abuse disorder and has replaced the outdated term dual diagnosis.


  • 7.7 million adults have co-occurring mental health and substance abuse disorders
  • Among the 423 million adults with a mental health disorder, 18.2 percent also had a substance use disorder
  • Among the 20.3 million adults who have a substance use disorder, 37.9 percent have a mental health disorder
  • Nine percent of individuals with a co-occurring disorder received treatment for both their mental health disorder and substance use disorder
  • 3.9 percent of individuals with a co-occurring disorder received treatment only for their substance use disorder
  • 34.5 percent of individuals with a co-occurring disorder received treatment only for a mental health disorder


Causes of Co-Occurring Disorders

Although genetics is one of the contributing factors for the development of a mental health disorder or a substance use disorder, stress, and vulnerability early on in life also play a factor.

An individual can be genetically predisposed to developing either a mental health disorder or a substance use disorder; however, exposure, stress, and environmental triggers can all contribute to whether the individuals will “express” their mental health disorder.

A combination of underlying factors and exposure to stress must be present to develop symptoms. Maternal drug abuse during pregnancy, trauma, abuse, divorce, bullying, and homelessness are all environmental triggers that can lead to the development of a mental health disorder.

These triggers are especially important if the individual is genetically predisposed (their first-degree relatives have a history of a mental health disorder). The same holds for the development of a substance use disorder.



A Mental Health Disorder Can Enhance The Reward Effects Of Substance Abuse

An individual with depression, anxiety, or another type of mental health disorder may be more susceptible to the development of a substance use disorder. They may be more sensitive to the effects of alcohol or drugs.

For example, when an individual develops anxiety or depression, the use of drugs or alcohol can change activity in the brain that can enhance the drug’s rewarding effects, decrease the unpleasant side effects associated with alcohol and increase the urge to continue to use the drug of abuse.



Substance Abuse As An Unhealthy Coping Mechanism

Individuals may also use alcohol or drugs as a coping mechanism or to numb the emotional and mental pain associated with their depression or anxiety.

Although some drugs may temporarily reduce symptoms of mental illness, they can also exacerbate symptoms, both acutely and long-term.

Research has not concluded that substance abuse disorders are the cause of mental health disorders or vice versa; however, they each can be triggers for the development of one another.



Substance Abuse As A Trigger For Mental Health Disorders

Substance abuse is known to trigger or intensify feelings of loneliness, sadness, and hopelessness, which are all symptoms associated with depression.

Addiction can alter brain chemistry and pathways, making individuals more prone to depression, anxiety, paranoia, and aggressive behavior.

Substance use disorders can indirectly trigger mental health disorders through social and economic hardships.

Substance abuse can lead to incarceration, financial debt, abusive relationships, and other social stressors that can lead to the development of a mental health disorder.



Brain Regions Involved In Both Substance Abuse And Mental Health Disorders

Studies have shown that both mental health disorders and substance use disorders affect similar areas of the brain, which can explain why one disorder may trigger another disorder.

The circuits in the frontal cortex of the brain that mediate reward, decision making, impulse control, and emotions are directly affected by drug abuse and become disrupted in mental health disorders such as depression and schizophrenia.

Neurotransmitters such as dopamine, serotonin, and norepinephrine are also involved in neural pathways that are involved with both substance abuse and mental health disorders.



Tobacco And Schizophrenia

There is a strong association between mental illness, particularly schizophrenia, and the use of tobacco products.

Individuals with schizophrenia have the highest tobacco use (70 to 80 percent), with rates up to 5 times higher than the general population.

Brain studies have shown that the abnormalities in the brain circuits that are seen in schizophrenia are known to induce the rewarding effects of nicotine.



The Relationship Between Nicotine And Clozapine

Nicotine acts on the nicotinic acetylcholine receptor in the brain, creating an internal reward process and therefore easing symptoms associated with schizophrenia.

As a result, individuals with schizophrenia have a hard time quitting the use of nicotine not only because of its high addiction potential but also because of the effectiveness it has at reducing or masking symptoms of schizophrenia.

Clozapine is an antipsychotic that treats schizophrenia and acts at nicotinic acetylcholine receptors, the same receptors as nicotine. Clozapine cannot only help alleviate the symptoms of schizophrenia, but it can also help individuals quit smoking by serving as a replacement for nicotine.



Integrated Treatment

If an individual enters treatment for a substance use disorder but has an undiagnosed mental health disorder that is not simultaneously treated, they are more likely to relapse.

Relapses often occur when one co-occurring disorder goes untreated, whether it is because the disorder has not yet been diagnosed or the treatment center does not specialize in co-occurring disorders.

Since co-occurring disorders often trigger one another, both disorders must be treated at the same time by the same treatment team.

Usually, the same coping techniques that are adopted to help overcome triggers associated with mental health disorders can also be used to help prevent cravings associated with substance abuse disorders.



Whether you or a loved one is struggling with a mental health disorder or a substance abuse disorder, AKUA can help.

AKUA Mind and Body is a Southern California mental health and substance abuse treatment center offering multiple levels of care for mental illness, addiction, and co-occurring disorders (dual diagnosis). We also have a strong alumni community for continued support post treatment.


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