Mental disorders can contribute to substance use and SUDs. Studies found that people with a mental disorder, such as anxiety, depression, or post-traumatic stress disorder (PTSD), may use drugs or alcohol as a form of self-medication.

There is a strong link between stress and substance abuse. Everyone copes with stress in different ways, but some people may resort to using drugs or alcohol to manage their stress. Conversely, the impact of substance misuse on a person's health, life, and relationships may cause excess stress.

“Substance use can worsen the course of another mental health condition and untreated mental health concerns can increase the vulnerability to high-risk substance use or developing a substance use disorder,” she added. “When both conditions are treated simultaneously, the chances of successful recovery improve.”