Department of Veterans Affairs (VA) did not have to pay benefits to alcoholics because their drinking was due to “willful misconduct.”1
As a result of the pioneering work of scientists at the Public Health Service Hospital in Lexington, Kentucky (Ludwig et al., 1978) and the discovery of the reward system by psychologists such as Olds (1958), our view of addiction has changed. We now know that addiction, defined as a compulsion to seek and take specific substances, is based on an aberration of normal brain function.
The reward system is a set of circuits and structures that work as a unit in lower animals as well as primates and humans. Previously, animals were thought to be incapable of addiction; now they can serve as models for research relevant to human patients. The reward system developed early in evolution and is present in modern humans in a form that remains essentially unchanged from that of our early ancestors (Maclean, 1955). It is a part of the brain that is essential for survival because it is activated by all types of rewards, including the basic ones such as food, water, and sex. Activation of this system (pleasure) produces reinforcement of specific behaviors that are needed for survival. The reward system also is involved in the formation of memories. The pursuit of pleasure and the avoidance of pain, at a very fundamental level, are completely normal.
Unfortunately, certain plant products, such as opioids and cocaine, are, by coincidence, able to fit perfectly into receptors in the reward circuits where they can directly produce a sensation of reward or euphoria. Other substances, such as alcohol, are able to activate the reward system by stimulating the release of neurotransmitters called endorphins or by other more complex mechanisms. While normal activation of the reward system by constructive behaviors is important for survival, activation of the reward system by the use of drugs can lead to behaviors that are nonproductive or harmful.
Whereas a sense of pleasure normally is earned through constructive behaviors and natural drives, even a small amount of cocaine can directly activate this same pleasure system without the need for the usual work. Cocaine’s chemical structure blocks the reuptake mechanism of the neurotransmitter dopamine. Normally, nerve cells release dopamine and take it back up again after their signals are sent; cocaine blocks the reuptake process, causing continued high stimulation of the reward system. Dopamine accumulates in the space between nerve cells where signaling occurs (the synapses), and the cocaine effect takes over or “hijacks” the reward system (Ritz et al., 1987). Other addictive drugs, such as alcohol, nicotine, marijuana, and opioids, also directly activate the reward system; although
1 Traynor v. Turnage, 485 U.S. 535 (1988).