Environmental Factor, October 2011, National Institute of Environmental Health Sciences
NIDA director visits NIEHS, provides addiction research update
Volkow considers herself a scientist first, but she is also noteworthy for being among the highest-ranking women scientists at NIH and the only Hispanic who is the director of an institute or center there. (Photo courtesy of Steve McCaw)
Joining her colleagues from throughout the Institute at the talk was Mary Wolfe, Ph.D., NTP deputy division director for policy and director of the Office of Liaison, Policy, and Review. (Photo courtesy of Steve McCaw)
Birnbaum, right, joined Volkow for the question-and-answer segment of the talk. (Photo courtesy of Steve McCaw)
Following her talk, Volkow met with several NIEHS and NTP scientists, including Michael Wyde, Ph.D., left, who talked with her about ongoing NTP cell phone studies. (Photo courtesy of Robin Mackar)
With her usual amount of passion, Director of the National Institute of Drug Abuse (NIDA) Nora Volkow, M.D., presented an update on drug abuse and addiction research during a noontime presentation Sept. 23, hosted by NIEHS/NTP Director Linda Birnbaum, Ph.D.
Volkow has been the director of NIDA since May 2003. NIDA supports most of the world's research on the health aspects of drug abuse and addiction.
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Volkow's remarks focused on a growing body of knowledge, demonstrating the role that brain circuits play in addiction, reemphasizing that addiction is in fact a brain disease, and providing updates on directions drug abuse researchers are taking to develop targeted medications to address these brain changes.
The role of dopamine
“We now know that all drugs of abuse which lead to addiction have a common characteristic in that they all increase the brain chemical dopamine in the nucleus accumbens,” Volkow said. She stated this has been shown in both animals and humans and is believed to be what causes the reinforcing and rewarding effects of drugs that ultimately lead to addiction.
She said what is puzzling is that in some cocaine studies, for example, subjects who are not given cocaine, but other drugs where the pharmacological effect is blunted, still want the drug. “What is driving them to take the drug if they aren't getting the reinforcing effects? That's something I want us to better understand.”
Volkow discussed this finding in relation to the elegant, early work of Pavlov, who conditioned dogs to salivate for food in response to an aural cue. She talked about how the brain learns to associate a stimuli with a reward and then become conditioned to expect the reward. The stimuli alone can create the reinforcing effect once the brain is conditioned.
“This is nature at its greatest magnificence," Volkow said, referring to the brain's ability to learn to predict reward and activate the dopamine system and drive behavior.
Volkow used a series of brain images during her talk to demonstrate how circuits are impacted by drugs of abuse and to illustrate that the brain has developed in such a way to be wired to respond to rewards. “If you start to mess with the natural wiring of the brain, the consequences can be so devastating,” she said.
The Complexity of the Issue
Before moving away from her brain circuitry update, Volkow underscored the complexity of addiction and how she wishes someone could develop a compound that could increase expression of what she referred to as dopamine 2 (D2) receptors, which are proteins that help bind dopamine in the brain. She suggested that the number of D2 receptors a person has seems to be an indicator of who might be more vulnerable to addiction. By understanding more about how D2 receptors function, she noted, “We would do a world of good, not just for drug addiction, but for other diseases involving self control.”
Cognizant of the time, Volkow shifted gears near the end of her talk from reward circuitry to what she referred to as the dark side of addiction, mentioning some nicotine research which helped identify a gene cluster association in an area of the brain called the habenula which has been shown to regulate dopamine cell firing and can inhibit dopamine neurons. “This is a fascinating new area that we are exploring.”
(Robin Mackar is the news director in the NIEHS Office of Communications and Public Liaison.)
Institutes with Common Interests
Volkow pointed out that this was the second time she had been to the beautiful NIEHS campus. She recalled her visit in March 2005 when she received the Spirit Award from the NIEHS Diversity Council (see story(http://www.niehs.nih.gov/news/newsletter/2006/april/spotlight-nida.cfm))
Volkow spent time talking about some of the commonalities between NIEHS and NIDA. “Drugs are chemicals, which are ultimately environmental exposures, which makes them of interest to both institutes,” she pointed out.
In addition to giving a public lecture, Volkow took time during her rainy day trip to North Carolina to meet with members of the leadership team and with key staff from the extramural research and training division and with the two intramural divisions, the Division of Intramural Research and the Division of the NTP.