Just say know! talk describes effects of drugs on the brain

By: Anna Carmichael,  A&S Communications
May 18, 2017

Ronald Harris-Warrick, the William T. Keeton Professor of Biological Sciences in the Department of Neurobiology & Behavior, spoke to students April 12 as part of the Bethe Ansatz “Building a Life Worth Living” series. His lecture,  “Just say know! Effects of psychoactive drugs on the brain,” was related to the same material he teaches in one of his classes, “Drugs and the Brain,” which is an introduction to neuropharmacology with an emphasis on psychoactive drugs.
 
“You are going to be offered drugs during your college years,” Harris-Warrick told the group of students. “They are available everywhere and your early 20s are the peak of experimentation. It is up to you to decide how to deal with them”
 
Although there may be some pressure to experiment with drugs, Harris-Warrick said, “the large majority of students do not use drugs beyond alcohol. My feeling is that it will be useful to understand what these things actually do to the brain.”
 
To begin the lecture, Harris-Warrick asked students to think about which drugs were most harmful: heroin, alcohol, marijuana, cocaine or tobacco. Students raised their hands to vote for different drugs, but when they were asked to think about it, they realized it was a deeper question, one involving several factors.
 
Harris-Warrick said students need to consider the different kinds of harms drugs can cause: an arrest for using the drug, death from a drug overdose; becoming addictted to a drug or the impacts on others who are indirectly affected by the user.
 
At the end of the discussion, students agreed that tobacco caused the most deaths, but alcohol was the most harmful when considering all other factors.
 
Harris-Warrick said that the reason why these drugs are addictive comes from their actions in the brain on the so-called dopamine reward pathway.  In this pathway, dopamine is released at a level that indicates whether a reward that is received meets your expectation of how good it will be. An unexpected reward triggers dopamine release, while an expected reward does not. Addictive drugs like nicotine, alcohol, heroin and cocaine act directly to enhance dopamine release, bypassing the brain’s normal evaluation of the reward. Thus, the response to an addictive drug is signaled as always better than expected, driving behaviors to try to get more of it. This leads to addictive behavior.
 
Environmental cues can also become associated with the availability of addictive drugs and can elicit strong craving that reinforces drug use. For example, perhaps you see a stop sign by the store where you buy cigarettes. Now, whenever you see stop signs, you crave cigarettes. These cues, cravings, physical effects and responses can all make it very hard to quit a drug once you begin taking it
 
The Bethe Ansatz after-dinner conversations are weekly, hour-long informal talks in Professor Julia Thom-Levy’s apartment. Thom-Levy is house professor in Bethe House, as well as professor of physics and the Provost’s Fellow for Pedagogical Innovation. The conversations are dedicated to engaging students with faculty and visitors aimed at broadening horizons and opening minds. For more information about these conversations, visit http://blogs.cornell.edu/betheansatz/about/.
 
Anna Carmichael ‘18 is a communications assistant in the College of Arts & Sciences.

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