Never Enough: Homeostasis, Marijuana and Opiate Addiction

JUDITH GRISEL, Ph.D., is an internationally recognized behavioral neuroscientist and a professor of psychology at Bucknell University with expertise in pharmacology and genetics whose research focuses on determining root causes of drug addiction. A current focus of her laboratory is to understand the role of endogenous opiate neurotransmission in different trajectories of alcohol abuse in men and women. Professor Grisel recently published Never Enough: The Neuroscience and Experience of Addiction, a New York Times bestseller.

Never Enough

Regular use of any psychoactive drug causes the opposite effect. Chronic stimulants result in lethargy, sedatives lead to anxiety, and euphoriants guarantee misery. These consequences are so predictable because they follow directly from fundamental features of the nervous system, namely, its capacity to recognize, predict, and adapt to change. We will apply Solomon and Corbit’s Opponent Process Theory (1974) to understand the neural and behavioral changes wrought by chronic exposure to cannabinoids and narcotics and discuss how such adaptation during periods of rapid brain development results in lasting changes in brain structure and function that pave the way for future addictions.

Among the many studies conducted by Dr Grisel, is a 2018 set of findings on the neuroscience of addiction pointing out genetic risks of addiction, especially in women. Gender and the biology of the brain may make some women more likely to reach for a drink when they feel stressed out, and more likely to become dependent on alcohol. It was funded by the National Institute of Alcoholism and Alcohol Abuse and published in the journal Addiction Biology.

This finding, the outcome of three-year neuroscience study by Bucknell Professor Judith Grisel, could improve the screening and diagnosis of alcoholism and other addictions. It also adds to the mounting body of evidence about fundamental differences between the brains of men and women — differences that Grisel notes were ignored for decades, leaving a deep gender gap in medical research that persists today.

Learning Objectives

1. Understand how abused drugs coopt normal brain circuits to mark meaningful events
2. Recognize that repeated exposure to these signals produces adaptation in the brain, as any routine perturbation leads to neural compensation in the form of an “opponent process” aimed at maintaining homeostasis
3. Tie opponent processes to the hallmarks of addiction: tolerance, dependence and craving
4. Know how endogenous opiate pathways are exploited by recreational users and how natural antiopiate mechanisms undermine an addict’s efforts to get high
5. Appreciate how the specific actions of delta-9-THC in the bring about subjective effects, as well as the profound neural adaptations to counteract these outcomes
6. Connect robust brain plasticity in adolescents to an enhanced risk for addiction