Thursday, April 5, 2007
Neurobiology of Addiction
By George F. Koob and Michel Le Moal.
(Elsevier), London, 2006.
Over the past twenty-five years, the neurobiology of addiction has become established as an important arena of scientific study. In particular, the molecular adaptations the brain makes in response to addictive drugs has placed addiction squarely in the forefront of modern brain science.
Dr. George F. Koob, a respected American alcoholism researcher of long standing, has put together an academic treatise beyond the expertise and the pocketbooks of most laypersons, but the book is of crucial importance in the burgeoning
field of addiction science.
In Neurobiology of Addiction, Koob and co-worker Michel Le Moal review the neural and molecular mechanisms responsible for the effects of individual addictive drugs in five categories--psychostimulants, opium, alcohol, nicotine,and cannabis.
Particularly well documented is the “anti-reward” system, by which the abuse of addictive drugs leads to a net decrease in dopamine and serotonin in the nucleus accumbens,the brain structure associated with withdrawal and craving. Thus, the
pursuit of artificial pleasure becomes, through the process of addiction, a state of chronic depletion of the brain neurotransmitters associated with states of joy, happiness and well-being.
The authors also do a good job of putting forth their theory of “allostasis,” defined as a “state of chronic deviation of the regulatory system from its normal (homeostatic) operating level.” The addicted brain is constantly attempting to normalize through counteradaptions at the neural level, as well as by switching on the body’s stress responses. Craving and anxiety are among the behavioral results.
[For more on George Koob,
The Chemical Carousel: What Science Tells Us About Beating Addiction © Dirk Hanson 2008, 2009.
--Koob, George, and Le Moal, Michel. “Drug Abuse: Hedonic Homeostatic
Dysregulation.” Science. October 3, 1997. 278: 55.
--Everitt, Barry J. “From the Dark Side to the Bright Side of Drug Addiction.”
Science 314 p. 59, 6 October 2006.