Case Teaching Notes for
“I Can Quit Anytime I Want: The Biological Basis of Euphoria and Addiction”

Introduction / Background

This case study is a “clicker case.” It combines the use of student personal response systems (clickers) with case teaching methods and formats. The case is presented in class using a series of PowerPoint slides in parts, or stages. After each stage, students are asked to respond to questions (called “clicker questions”) posed by the instructor. Students work their way through the material to understand the problem presented in the case. Specifically designed for use in large introductory science classes, the method integrates lecture material, case scenario material, student discussion, (clicker) questions, clarification of the answers to those questions, more lecture, and data.

This case follows Ashley and her boyfriend Sean through his struggle with his cocaine addiction. The case discusses the biological basis of the temporary euphoria that may accompany drug use and certain aspects of the biological basis of addiction. It also introduces neurotransmitters and their mechanisms of action at a synapse. It does not attempt to address all of the complexities or biological mechanisms of addiction, but discusses general concepts using cocaine and opiates as examples. While the characters are fictional, the case is based on the true stories of people struggling with this disease.

Discussing addiction can be a powerful way to relate concepts to students’ everyday lives. Most college students are exposed to addictive substances at some point. Furthermore, a 2007 report from the National Center on Addiction and Substance Abuse (CASA) at Columbia University found that college students have higher rates of alcohol or drug addiction than the general public: 22.9% of students meet the medical definition for alcohol or drug abuse or dependence—a compulsive use of a substance despite negative consequences.

Students should have prior knowledge of the parts of a neuron and a basic understanding of nerve impulses (action potentials) before being presented with this case.

Objectives

Upon completion of this case, students should be able to:

• Describe how neurotransmitters are removed from a synapse.
• Explain the sequence of events involved in communication at the synapse.
• Recognize that there is a biological basis for dependency to certain drugs.
• Understand that certain drugs interfere selectively with neurotransmission.
• Describe two ways that drugs can increase dopamine levels in a synapse.
• Recognize that normal behaviors can activate the reward system in the brain and that drugs of abuse affect those same reward circuits.

Misconceptions

• Students may not understand that the neurotransmitter left in the synapse is either broken down by enzymes or is taken back up by the pre-synaptic neuron.
• Many people believe that addiction is not a physiological condition and that stopping is just a matter of willpower or strength.

Classroom Management / Blocks of Analysis

This case was written for a large section of an introductory biology course for both science majors and non-majors that uses personal response systems or “clickers.” The text of the case is included in the PowerPoint presentation. Since students read at different rates, instructors are advised not to move too quickly through the text slides. As new concepts are brought forward in the case, instructors should be prepared to stop and discuss these as appropriate. Students may volunteer information about friends and family members who have struggled with addiction, or even their own experiences.

Teaching the Case

Slide 1: Title slide.

Slide 2 and Slide 3: These two text slides introduce students to Ashley, Ashley’s roommate Sheila, and Ashley’s boyfriend Sean. Ashley has just discovered Sean’s cocaine use. These slides also mention possible warning signs of substance abuse, including not being able to stop using whenever one wants.

Slide 4: This slide presents the first clicker question, which asks students if they know anyone who is addicted to drugs or alcohol. This helps to add personal involvement to the case. Instructors may wish to mention here the statistics mentioned above—namely, that a 2007 report from the National Center on Addiction and Substance Abuse at Columbia University found that college students have higher rates of alcohol or drug addiction than the general public: 22.9% of students meet the medical definition for alcohol or drug abuse or dependence—a compulsive use of a substance despite negative consequences.

Slide 5: Sheila explains that addiction has a neurological basis. Instructors can use the graphic on this slide to introduce (or review) the major parts of a nerve cell.

Slide 6: This text slide introduces neurotransmitters and their basic function (communication). The table included in the slide lists four well-known neurotransmitters. Instructors may wish to mention to students that these are just examples, as there are over 100 different neurotransmitters.

Slide 7: The text and graphic on this slide explain what causes a neurotransmitter to be released. The graphic can be used to point out that two neurons (or a neuron and a target tissue) usually are not actually connected, so a neurotransmitter is released into the synapse. Although it is not an objective of this case, an instructor may wish to explain that it is actually the properties of receptors to which a neurotransmitter binds that determines if the neurotransmitter will have an excitatory or inhibitory effect.

Slide 8: This graphic is a close-up of a synapse illustrating neurotransmitters and receptors. The neurotransmitters are stored in vesicles (illustrated by the light circles) before they are released.

Slide 9: This slide includes a link to a PBS website with animations explaining how nerve cells communicate. This website can also be used to introduce how drugs influence neurons. Instructors should use their discretion regarding how much of the material on this site to use. The different aspects illustrated are:

• Different parts of the brain influence different functions.
• The brain’s reward pathway (ventral tegmental area, the nucleus accumbens, and the prefrontal cortex).
• Nerve impulses (action potentials).
• The synapse.

Slide 10: This text slide explains how neurotransmitters can be removed from a synapse. (Neurotransmitters may also diffuse away from the synapse.)

Slide 11: This slide presents clicker question #2, an application question about what would happen if acetylcholine could not be broken down.

Slide 12: Clicker question #3 is a “recall question” designed to re-emphasize the function of dopamine (pleasure). This also introduces the next part of the case, which discusses dopamine in more detail.

Slide 13: This text slide explains how dopamine is removed from a synapse.

Slide 14: Graphic illustrating how dopamine is removed from a synapse.

Slide 15 and Slide 16: These two text slides continue the story. They emphasize that dopamine is found in the brain normally, but drugs can cause problems. Ashley wants to know why Sean seems to be unable to simply quit using cocaine, a fairly common question family and friends of addicts have.

Slide 17: This slide illustrates that normal stimuli (such as food) cause the release of dopamine and that cocaine greatly exaggerates dopamine levels.

Slide 18 and Slide 19: Graphics illustrating the reward pathway in the brain (areas where drugs like cocaine have their effect).

Slide 20: This slide describes the action of cocaine at a synapse. Cocaine prevents the reuptake of dopamine, thereby increasing the amount of dopamine in the synapse.

Slide 21: This slide includes a link to animations about cocaine. The first animation shows release and reuptake of dopamine in a synapse without cocaine. Instructors should then click “add cocaine” to see the effect cocaine has on the reuptake of dopamine.

Slide 22: Text slide that continues the story. Instructors should point out that Sean’s body has become used to the increased dopamine levels. Now the only time Sean feels good (or even okay) is if his dopamine levels are high.

Slide 23: Clicker question #4 tests students’ understanding of the action of cocaine.

Slide 24: Text slide that continues the story. This slide points out that some people become addicted quickly while others do not. The reason for this difference is not fully understood.

Slide 25: Graphic showing cocaine use by selected age groups. Students will note that they may be in the age group that uses cocaine the most.

Slide 26: Clicker question #5 asks students to form a hypothesis. After the correct answer is revealed, students will have an understanding of one factor involved with drug tolerance.

Slide 27: Text slide that continues the story. Sean realizes he is addicted and needs help.

Slide 28 and Slide 29: Text slides that introduce the idea that not all drugs work in the same way. The drug naltrexone is introduced here. Sean learns that naltrexone is not a cure for addiction, but that behavioral therapy is the tool that could help him. The purpose of mentioning this drug is to lead into the next part of the case, which teaches that not all drugs work in the same way. This case does not attempt to explain the action of naltrexone or any other medicine used to treat addictions.

Slide 30: This slide links to animations about opiates. The first animation shows how dopamine works in a synapse without opiates. Instructors should then click “add opiates” to see the effect opiates have on dopamine secreting neurons.

Opiates bind to opiate receptors on another neuron. This causes the amount of dopamine in the synaptic clefts in the reward pathway to increase dramatically. One theory is that when the opiate binds to the receptors on the third neuron shown, that neuron releases less GABA, which is a neurotransmitter that inhibits dopamine. (If there is less GABA, therefore, there is more dopamine.) Instructors can explain this in detail if they wish; however, it is included in this case primarily to illustrate there are other ways drugs influence dopamine levels. There are still additional mechanisms used by addictive drugs, but these are beyond the scope of this case.

Slide 31: Clicker question #6 asks students to form a hypothesis. After the correct answer is revealed, students will have an understanding of how a prescribed drug works and also why it doesn’t work on all types of addiction.

Slide 32: The story concludes with Sean and Ashley expressing concern that their children may become addicted to drugs or alcohol in the future.

Slide 33: A graphic that summarizes addiction risk factors. This is mainly for student interest.

Answer Key

Answers to the questions posed in the case study are provided in a separate answer key to the case. Those answers are password-protected. To access the answers for this case, go to the key. You will be prompted for a username and password. If you have not yet registered with us, you can see whether you are eligible for an account by reviewing our password policy and then apply online or write to answerkey@sciencecases.org.

References

Supporting Material

The following three resources come from the PBS website Close to Home—Moyers on Addiction.

How Brain Cells Communicate

http://www.pbs.org/wnet/closetohome/animation/neuron-main.html

This animation can either be used to introduce or review nerve cells, or not used at all based upon the discretion of the instructor.

How Cocaine Works in the Brain

http://www.pbs.org/wnet/closetohome/animation/coca-anim-main.html

This animation shows the release and reuptake of the neurotransmitter dopamine. After viewing, the instructor should click “add cocaine.” The animation then shows the action of cocaine at a synapse.

How Opiates Work in the Brain

http://www.pbs.org/wnet/closetohome/animation/opi-anim-main.html

This animation is simlar to the previous one, only it shows the action of opiates at the synapse.

Websites

From the National Institute on Drug Abuse:

Addiction: “Drugs, Brains, and Behavior—The Science of Addiction”

http://www.drugabuse.gov/scienceofaddiction/

The Neurobiology of Drug Addiction

http://www.nida.nih.gov/pubs/Teaching/Teaching2/Teaching2.html

NIDA InfoFacts: Crack and Cocaine

http://www.nida.nih.gov/Infofacts/cocaine.html

Research Report Series—Cocaine Abuse and Addiction

http://www.drugabuse.gov/ResearchReports/Cocaine/effects.html#effects

The Brain & the Actions of Cocaine, Opiates, and Marijuana

http://www.nida.nih.gov/pubs/teaching/Teaching4.html

From the U.S. Drug Enforcement Administration:

Drugs of Concern: Cocaine

http://www.deadiversion.usdoj.gov/drugs_concern/cocaine/cocaine.htm

Drug Information: Cocaine

http://www.usdoj.gov/dea/concern/cocaine.html

From the National Institutes of Health:

The Brain: Understanding Neurobiology Through the Study of Addiction

http://science-education.nih.gov/customers.nsf/HSAddiction.htm

Slide Credits

Acknowledgements: This material is based upon work supported by the NSF Grant No. DUE-0618570. Any opinions, findings, conclusions, or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of NSF. Additionally, the author would like to thank Drs. Clyde F. Herreid (University at Buffalo), Mary Lundeberg (Michigan State University), and Eric Ribbens (Western Illinois University) for their guidance and critical evaluation of the case.

Date Posted: November 16, 2009.

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