Attention-deficit hyperactivity disorder (ADHD) has been shown to have a high psychiatric comorbidity. Substance abuse disorders are medical conditions that are characterized by problematic use of substances. This abnormal substance use can have numerous negative effects, such as impaired control, interpersonal problems, as well as physical and psychological problems.

It is said that the link between ADHD and SUDs exists due to an impairment of the reward system in the brains of those who have ADHD.