A substance use disorder (SUD) is a mental disorder that affects a person’s brain and behavior, leading to a person’s inability to control their use of substances such as legal or illegal drugs, alcohol, or medications. Symptoms can range from moderate to severe, with addiction being the most severe form of SUDs.
Researchers have found that about half of individuals who experience a SUD during their lives will also experience a co-occurring mental disorder and vice versa. Co-occurring disorders can include anxiety disorders, depression, attention-deficit hyperactivity disorder (ADHD), bipolar disorder, personality disorders, and schizophrenia, among others. For more information, please see the National Institute on Drug Abuse (NIDA)’s Common Comorbidities with Substance Use Disorders Research Report.