What is Substance Use Disorder (SUD)?

Substance use disorder (SUD) is a treatable mental disorder that affects a person's brain and behavior, leading to their inability to control their use of substances like legal or illegal drugs, alcohol, or medications. This affects the person's ability to function in day to day life. People keep using the substance even when they know it is causing or will cause problems. The most severe SUDs are sometimes called addictions.

People with a substance use disorder may have distorted thinking and behaviors. Changes in the brain's structure and function are what cause people to have intense cravings, changes in personality, abnormal movements, and other behaviors. Brain imaging studies show changes in the areas of the brain that relate to judgment, decision making, learning, memory, and behavioral control.

Repeated substance use can cause changes in how the brain functions. These changes can last long after the immediate effects of the substance wears off, or in other words, after the period of intoxication.

Intoxication from a substance is the intense pleasure, euphoria, calm, heightened sensory perception, and other feelings. Intoxication symptoms vary depending on the substance involved

Source: American Psychiatric Association