What’s the Connection Between Mental Illness and Substance Abuse?

Adolescence is a time of immense growth and change in a teen’s life, but those changes may also be occurring in how a young person’s brain is developing. In some cases, these changes may even lead to the development of a mental illness or a substance abuse problem. Especially considering this tenuous time in a teenager’s life, it’s important to examine the ties between the two diagnoses and how they might affect each other.

There are overlapping issues that cause addiction and mental illness, such as underlying brain deficits, genetic vulnerabilities, and/or early exposure to stress and trauma, according to the National Institute of Drug Abuse (NIDA).

Individuals with mental illnesses that are left untreated by a professional will often self-medicate with drugs and alcohol. These habits can worsen their existing mental state or be the cause of the development of a mental illness that was not present before.

People most commonly develop drug habits during their teen years, since this is also when signs of mental illness begin to show. It is at this stage in life when a person is most vulnerable—especially since the brain is still developing—and drug use can interfere with that development and function.


It is more likely that a child or teen will develop a substance abuse problem if they are left with an untreated mental illness, rather than someone of the same age who does seek treatment. An untreated dual diagnosis (a substance addiction and a mental illness) can follow a person into adulthood; approximately 8.4 million adults have co-existing disorders, according to the Substance Abuse and Mental Health Services Administration.

Studies show that people who do not receive proper treatment as teens end up paying more in health care costs and services when they’re adults. Other studies show that parents are increasingly concerned about their teen’s mental illness nowadays, even more so than the possibility of them having a substance abuse problem.

Still, many people are in denial about mental health issues, whether it is their own or their teen’s. Likewise, studies suggest that up to 90% of adolescents who need help with substance abuse issues are not receiving the help they need.

Treatment for substance abuse and mental health issues are available separately or in a joint program that focuses on both issues. It is best to consult your family doctor, therapist, counsellor or an addiction specialist for more information on what your teen needs in terms of treatment.

Photos: Jens JohnssonDave Meier