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Substance Use Disorder is a syndrome where a person compulsively uses substances despite many negative experiences and harmful consequences.

Individuals who experience severe substance use disorder symptoms have an intense desire to use certain substances like alcohol or drugs, regardless of the problems that come about by consuming them. Gambling Disorder is new to the DSM-5, and is characterized by repeated gambling despite extremely negative consequences affecting the whole family.

Neurobiology of Addiction refers to the of changes in the brain circuits of an individual after repeated use. In the most severe cases, there are changes in the reward system, decision making, and self-control become impaired. The specific changes in the brain will depend upon what addictive substance is used: alcohol, opioids, cocaine. These agents induce an increase in dopamine in the part of the brain called the basil ganglia which in turn produces an intense feeling of pleasure. The other part of the brain referred to as the prefrontal cortex becomes impaired after repeated substance use, which makes stopping more difficult. After repeated use, tolerance develops, and the brain needs more of the substance to create that experience of pleasure. This can make life without the substance feel less enjoyable. When a person experiences the pain of withdrawal symptoms, they will seek to use substances in order to reduce those distressing feelings associated with withdrawal (Koob & Volkow, 2010, Koob, 2013).


There are three clinical syndromes involved in the use of substances:

Substance Use Disorder causes cognitive, behavioral and physical symptoms regardless of the negative consequences inherent in their use. Some of these include an intense desire to use combined with an inability to control or cut down on substance use, and tolerance (needing more and more of the substance to feel the effect).

Substance Intoxication can cause slurred speech, impairment in memory, unsteady gait, incoordination, and at times stupor or a life-threatening coma after the recent ingesting of a substance. This condition can cause serious behavioral and psychological impairments and can significantly affect judgment.


Substance Withdrawal includes the reducing or stopping substance use that had been heavy and protracted. Signs of withdrawal include sweating, increased pulse rate, tremors, difficulty sleeping, nausea/vomiting, hallucinations, agitation, anxiety and seizures. Withdrawing from substance can be dangerous and should be supervised by medical professionals.


After repeated use of these substances, there can be significant changes in the brain’s wiring causing distorted thinking, behavior and bodily functions. There are also changes to the brain’s wiring and this can lead to intense cravings making it hard to stop using the substance. Brain imaging have shown alterations in the brain with regard to memory, judgment, decision-making and learning and these changes can be long lasting. Over time, tolerance can develop where larger amounts of a substance are needed to feel the effects (APA, 2013). 

Dr. George Koob Interview

Dr. George Koob is an internationally recognized expert on alcohol, stress, and the neurobiology of alcohol and drug addiction. He is the Director of the National Institute on Alcohol Abuse and Alcoholism, where he provides leadership in the national effort to reduce the public health burden associated with alcohol misuse. As NIAAA Director, Dr. Koob oversees a broad portfolio of alcohol research ranging from basic science to epidemiology, diagnostics, prevention, and treatment. Dr. Koob earned his doctorate in Behavioral Physiology from Johns Hopkins University in 1972. Prior to taking the helm at NIAAA, he served as Professor and Chair of the Scripps’ Committee on the Neurobiology of Addictive Disorders and Director of the Alcohol Research Center at the Scripps Research Institute.  Dr. Koob is the recipient of many prestigious honors and awards for his research, mentorship, and international scientific collaboration.  Dr. Koob has authored more than 650 peer-reviewed scientific papers and is a co-author of The Neurobiology of Addiction, a comprehensive textbook reviewing the most critical neurobiology of addiction research conducted over the past 50 years.

Dr. Anna Lembke Interview

Dr. Anna Lembke is an associate professor in the department of Psychiatry and Behavioral Sciences at Stanford University School of Medicine. She is Medical Director of Stanford Addiction Medicine, Program Director for the Stanford Addiction Medicine Fellowship, and chief of the Stanford Addiction Medicine Dual Diagnosis Clinic. Dr. Lembke was one of the first in the medical community to sound the alarm regarding opioid overprescribing and the opioid epidemic. In 2016, she published her best-selling book on the prescription drug epidemic, Drug Dealer, MD – How Doctors Were Duped, Patients Got Hooked, and Why It’s So Hard to Stop. Her book was highlighted in the New York Times as one of the top five books to read to understand the opioid epidemic.


Click the links below to find out more about Substance Use Disorders.

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