Dual diagnosis is the detection of an underlying condition accompanying another condition. For example, a patient undergoing initial medical examination at a drug treatment center may be diagnosed with depression in addition to the primary condition of substance use. The depression may be a result of substance use or depression may have triggered substance abuse. Both conditions must be treated simultaneously in order to achieve the most successful outcome.

When an individual experiences an emotional or psychiatric condition, there is a higher likelihood that they may turn to drugs or alcohol to temporarily alleviate their symptoms.

If one condition is treated without treating the underlying condition the chance of relapse is higher.

The relationship between drug use and mental illness

People with drug and alcohol addiction are prone to developing mental illness and it works both ways; people with certain mental illnesses tend to develop substance use problems. According to the National Alliance on Mental Illness (NAMI), about a third of all people experiencing mental illness and about half of those living with severe mental illness also experience substance use. In those with substance use, about a third of alcoholics and more than half of all drug users report experiencing a mental illness.

The numbers can be higher depending upon the nature of the mental illness. Conditions such as post-traumatic stress disorder, antisocial personality disorder, anxiety, sleep disorders or depression increase the likelihood of addiction.


Although researchers don’t know exactly why such people are at an increased risk of addiction, it has been observed that:

  • Abruptly stopping use of alcohol can lead to withdrawal symptoms, including hallucinations that can resemble schizophrenia symptoms
  • Alcoholism and drug abuse can cause brain changes which can cause personality changes and mental disorders
  • Alcoholics of both genders often experience depression and anxiety disorders. Men are more likely to show antisocial personality disorder than non-abusers of alcohol

How is a dual diagnosis treated?

Treatment will not be the same for everyone but the mental illness and substance abuse will be treated at the same time. The first step is detox, or ridding the body of the substance being used, whether it is drugs or alcohol. This is best accomplished as an inpatient with medical supervision. Detox as an inpatient means the process can be accomplished in a consistent manner with no exposure to people and places associated with using.


Psychotherapy is an important part of effective treatment for patients with a dual diagnosis. Cognitive behavioral therapy in particular is useful in teaching patients how their beliefs and behaviors are influenced by negative thought patterns. Learning to identify and change old thought patterns and replace them with new ones improves the symptoms of both substance use and mental illness.

Other factors

  • Genetics – a person having close blood relatives with substance use and a mental disorder increases their likelihood of developing the same conditions. Studies comparing identical and fraternal twins found more instances of having two disorders among the identical twins, indicating that genetics plays a part
  • Chemical deficiency – a reduction in the amount of serotonin, a chemical essential to brain function, may be responsible for alcoholism and mood disorders coinciding so often. There is also evidence that addiction and mental health disorders are associated with the dysfunction of a group of brain chemicals called monoamine oxidases
  • Shared environment – studies involving twins revealed that environment plays a significant role in the development of a substance use problem and a mental health disorder

Self-help and support groups

Support groups allow participants to share frustrations, successes, problems and referrals to helpful specialists in recovery. Encouragement and friendships can be found which prevent the isolation common to those recovering from a dual diagnosis condition.