Mental illness, drug abuse, and addiction co-occur at very high rates. The Substance Abuse and Mental Health Services Administration (SAMHSA) reports that according to the National Survey on Drug Use and Health (NSDUH) in 2014, close to 8 million American adults suffered from both addiction and a mental health disorder at the same time.

When two disorders appear in the same person at the same time, they are said to be co-occurring. Mental illness can be a precursor to drug abuse, as individuals may turn to illicit drugs as a way to cope with difficult symptoms of their disorder, in a form of self-medication. Many drugs can seem to temporarily relieve some of the side effects of mental illness. For example, opioid drugs like heroin and prescription painkillers induce a sense of calm and relaxation while also increasing feelings of happiness. These drugs may temporarily dispel anxiety and depression then. Drugs can also offer an escape from reality – from troubling thoughts, stress, and other difficult emotions that often accompany a mental health disorder.

  • Mental health disorders are often considered risk factors for drug abuse. The National Institute on Drug Abuse (NIDA) publishes that those suffering from an anxiety or mood disorder are twice as likely to also battle a drug use disorder than their peers without mental illness. Individuals who battle drug use disorders are also twice as likely to also suffer from a mental illness like an anxiety or mood disorder, NIDA expounds. Long-term drug use can cause a person to become dependent on drugs and suffer withdrawal symptoms like depression and anxiety when drug use is stopped.
  • Drugs can also potentially cause symptoms of mental illness to appear. Extensive marijuana use may induce psychosis, for example, and may potentially increase the risk for a particularly vulnerable person to develop schizophrenia as a result, the Psychiatric Times warns. Hallucinogenic drugs induce an altered state of mind that may also be accompanied by psychotic thoughts and actions, and can lead to flashbacks 5-50 percent of the time, the journal Therapeutic Advances in Psychopharmacology publishes. These events where users re-experience the drug’s effects months or even years after stopping use may become persistent and chronic; they can lead to a disorder called hallucinogen persisting perception disorder (HPPD). Drug abuse, especially when perpetuated regularly, can damage brain cells and function, and this may then increase the odds for mental illness as well.

Shared Risk Factors

There are several potential risk factors that are shared between mental illness and ongoing drug abuse, which include:

  • Genetic vulnerabilities: Many mental illnesses are heritable, meaning that family members of those who suffer from substance use disorders may be more susceptible to developing them. Addiction is also considered to be heritable around half the time, the journal Psychiatric Clinics of North America publishes.
  • Environmental factors that overlap: Traumatic events and high levels of stress can cause a person to be more likely to experiment with drugs and may also make them more vulnerable to mental illness.
  • Early exposure: Drug use can damage the brain in such a way that it predisposes a person to both mental illness and addiction later in life, NIDA warns. Both drug abuse and mental illnesses are often developmental disorders, presenting in adolescence, and drug exposure during this time can induce negative changes in the brain.
  • Impact of similar brain regions: The stress response, reward processing center, and impulse control functions of the brain are commonly disrupted by drug abuse. These same parts of the brain may be dysfunctional in someone struggling with mental illness.
  • Drug abuse can complicate and exacerbate mental illness, and vice versa. Symptoms of mental illness are compounded by drug abuse, and drug abuse may be exacerbated due to mental illness. Because of this, both disorders need to be treated in an integrated and simultaneous fashion to ensure that both the drug abuse and the mental illness are properly managed.
  • Mental health and medical professionals should work together to design and carry out a treatment plan that can improve the side effects and symptoms of both disorders and enhance long term-recovery. Both residential and outpatient treatment programs offer many care options for those with co-occurring disorders, and trained professionals can help families decide on the best plan for their loved one. Medications, therapeutic techniques, and supportive care are all important aspects of a comprehensive treatment plan to address co-occurring mental illness and drug abuse.