A Very Fine House: A Mother's Story of Love, Faith, and Crystal Meth

by Barbara Cofer Stoefen

The function of dopamine is another powerful component in understanding addiction. Dopamine is a neurotransmitter, or chemical of the brain, and part of the body’s natural reward system. It is key to many brain functions such as motivation, learning, memorization, and motor control. Nearly all drugs of abuse have the ability to enhance dopamine transmission, and the euphoria experienced by a person in the early stages of drug use is a result of the dopamine process. It was long held by scientists that this pleasurable effect, or the “liking” of the drug, at least in part accounted for the development of addiction. It was the hedonic reward that perpetuated the drug use. The incentive sensitization theory, however, proposed by Dr. Terry Robinson and Dr. Kent Berridge, neuroscientists at the University of Michigan, suggests that the reverse may actually be true. Many individuals describe an actual decrease in drug pleasure after prolonged use, yet they experience continued craving (“wanting”). The incentive sensitization theory poses that addictive drug use in susceptible people creates very long-lasting brain changes in dopamine-related systems, leading to intense incentive motivation for drugs, or excessive “wanting” where drugs are irrationally craved. While “liking” and “wanting” drugs are strongly linked when drug use begins, only “wanting” becomes sensitized and thus more intense as addiction develops.*