A substance use disorder (SUD) is a diagnosed disease that involves drug and/or alcohol use that causes impairment. SUDs can occur at three levels of severity, according to the Diagnostic and Statistical Manual of Mental Disorders (DSM). Addiction is the most severe level of substance use disorders; lower levels can include substance abuse or dependence without addiction.
Drug and alcohol abuse is any hazardous overindulgence in drugs or alcohol or the use of prescription drugs beyond what is directed by a medical professional. Substance abuse is closely related to dependence and addiction. Though it’s possible to abuse drugs without developing an addiction, it greatly increases your risk of developing a more severe SUD.
Dependence refers to a physical or psychological reliance on a drug. Chemical dependence involves changes in your brain’s chemistry as it comes to rely on a drug. If you stop using a drug after developing a chemical dependency, you may start to experience uncomfortable withdrawal symptoms.
Addiction is the worst form of a substance use disorder. It involves compulsive use of a drug that can be extremely difficult to overcome.
Different drugs may cause different signs and symptoms of abuse. For instance, drugs like marijuana may cause bloodshot eyes, and heroin use may leave track marks on a person’s arm. Many drugs cause dilated pupils, changes in weight, and changes in energy levels. Frequent use of a drug can change your brain’s chemistry, which can lead to depression or anxiety. Other common signs are:
After high doses and frequent or long-term use of an addictive substance, you may start to experience a chemical dependency. Dependence on a substance may mean your SUD is getting more severe, and it’s starting to change your brain chemistry. Drugs can interact with important chemicals in the brain like endorphins, serotonin, and dopamine.
As your brain adapts to the drug, it may start to produce more or less of its natural chemicals. You may need higher doses to feel the same effects as your tolerance grows. If you try to cut back or stop, uncomfortable and even dangerous withdrawal symptoms may occur. Signs and symptoms of dependence may include:
Addiction, also called a severe substance use disorder, is identified by the compulsive use of a drug despite the consequences. Addiction can cause you to prioritize substance use over other basic needs, which can lead to severe consequences like job loss, health issues, and legal trouble. Other signs and symptoms of addiction can include:
American Psychiatric Association. (2017, January). What Is Addiction? from https://www.psychiatry.org/patients-families/addiction/what-is-addiction
American Psychiatric Association. (n.d.). Diagnostic and Statistical Manual of Mental Disorders (DSM–5). from https://www.psychiatry.org/psychiatrists/practice/dsm
National Institute on Drug Abuse. (2019, November). 8: Definition of dependence. from https://www.drugabuse.gov/publications/teaching-packets/neurobiology-drug-addiction/section-iii-action-heroin-morphine/8-definition-dependence
National Institute on Drug Abuse. (2019, November). 6: Definition of tolerance. from https://www.drugabuse.gov/publications/teaching-packets/neurobiology-drug-addiction/section-iii-action-heroin-morphine/6-definition-tolerance
World Health Organization. (2019, November 12). Substance abuse. from https://www.who.int/topics/substance_abuse/en/