As late as the 1990’s, an addict would enter a treatment facility and not receive the help they really need. Let’s say they had depression as well as issues with alcohol abuse. They’d be sent away, and told to take care of the mental health problem. Luckily, since then, rehabilitation centers started to address the problem, with the knowledge that both mental illness and addiction are two sides of the same coin.

It’s commonly known that 50 percent of drug addicts also have problems with a mental illness. Many addicts without knowledge of their mental illness often self-medicate, or use in order to combat feelings of sadness, anxiety, disorientation, hallucinations—whatever mental illness they are dealing with. Drugs might help to relax and calm you down; alcohol might help to blur the lines between sadness and contentedness. Heroin produces a high with such intensity that pleasure centers in the brain are immediately affected, and an addiction develops very quickly. This intense high can alleviate the symptoms that make the addict feel as though they are in a mental prison, if only very briefly.

Many different kinds of mental illness produce specific symptoms that they attempt to combat. For example, someone with anxiety might choose to use benzodiazepines, such as Xanax, a prescription normally reserved for anxiety and panic disorder. But if they develop a dependency, they might doctor-shop—or go to different doctors to pick up different prescriptions. While they might have symptoms that Xanax can relieve, they’re still not using them properly.

Or, if someone is experiencing psychosis—or a state of severe disorientation, reckless behavior, hallucinations and more—or another reaction, they might use recklessly. Not always to combat a symptom (though this is usually done unconsciously), but as part of a state of unusual behavior and as reaction to an uncovered mental illness.

In any case, dual diagnosis is one of the most crucial elements of an integrated rehabilitation program. Mental illness is common, and many suffer, some unknowingly. By helping addicts to overcome the symptoms of both mental illness and addiction, rehabilitation centers are helping those struggling with substance use disorder to become sober in the long run.