Studies have shown that there is a huge overlap or comorbidity between substance abuse and mental illness. While it's hard to determine a causal direction between the two, it's clear that many people with substance abuse issues have a mental illness, and vice versa.
Most of the time, when someone suffering from both substance addiction and mental illness asks for professional help, the said professional is only able to treat one or the other, resulting in complications in the patient's recovery process. The opioid crisis, fueled by over prescription of painkillers, has had further devastating consequences on mental health.
