Neuroscientists on drugs

NEW ORLEANS—Although the understanding of the neurobiology of addiction has grown substantially in the last decade, this has not had much of an effect on federal drug policy, a roundtable of neurobiologists, policymakers, and criminologists said at the 33rd Annual Meeting of the Society for Neuroscience earlier this week.Glen Hanson, former director and now assistant director of the National Institute on Drug Abuse (NIDA), said during the discussion on Tuesday (November 11) that among policymakers, drug abuse is seen through the opposing lenses of science and morality, and as a result, science often takes a back seat. He offered as an example a government agency that asked for NIDA's imprimatur on a policy statement opposing needle replacement for HIV prevention. NIDA's exhaustive analysis of published studies found that needle replacement programs not only reduced HIV, but also decreased drug use, because addicts were more likely to be drawn into treatment programs. But instead of changing the policy statement, the agency issued it without NIDA as a cosignatory, and NIDA officials were castigated for not being “team players.” But neither did NIDA issue its own statement disagreeing with the policy. ”Sometimes you have to pick your battles,” said Hanson.NIDA Director Nora Volkow said that very long-term downregulation of dopamine receptors in the prefrontal cortex and elsewhere dampen the addicted brain's ability to respond to pleasure and other salient stimuli. Over time, drugs alone can provide the dopamine reward. At the same time, and perhaps even more importantly, changes in other brain centers reduce the signals that usually exert inhibitory control. “Without that,” said Volkow, “your ability to refrain, to say 'Maybe I shouldn't do it,' will be diminished.” Because of these long-lasting receptor changes, which are very well modeled in animal systems, Volkow said that addicts lose the ability even to recognize when the drug is no longer reinforcing: “I don't even know why I take the drug” is a common refrain among addicts, she said. The behavioral changes brought on by these neurobiological alterations last long after withdrawal of the drug, according to Charles P. O'Brien, vice chairman of the department of psychiatry at the University of Pennsylvania. Once you're addicted, he said, “just saying no really doesn't work.” No one type of treatment—psychotherapy, twelve-step programs, medication—is successful alone for the large majority of patients, he said. Neither can short-term treatment bring about long-term change for most addicts: “This is a chronic disease—it doesn't go away.” New types of drugs that reduce craving are proving effective in clinical trials, O'Brien said, cutting relapse rates in half, but these are still not widely used in addiction treatment programs. “Neuroscience-based treatments are not getting used, although they could help society,” he said.But “judges and parole officers don't know any of this,” said Douglas B. Marlowe of the Treatment Research Institute at the University of Pennsylvania. “How has neuroscience penetrated social policy? The answer pretty obviously is not at all,” he said. On the other hand. Marlowe noted, it may not be appropriate to apply conclusions about severe addicts to other drug abusers: “That's where we tend to get into trouble.”Eighty percent of inmates are drug involved, said Marlowe, and “all of them, for all intents and purposes return to their pre-prison drug use” shortly after release. “You can't punish people enough to change their brain chemistry,” he said. “Prison has no effect on the drug use of offenders.”Neither, unfortunately, does much else, Marlowe said. Without coercion, up to two thirds of addicts don't show up for their intake appointments at community treatment centers, and more than half the remainder drop out within 3 months. Even in highly monitored programs, “there are, at best, small effects on high-risk addicts,” said Marlowe.A newer approach, called leveraged treatment, may be somewhat more effective. In this system, punishment—prison, eviction, loss of child custody—is withheld as long as the addict continues treatment, success is rewarded frequently, and the severity of threatened sanctions is gradually eased as progress is made. “For a drug addict, waiting a year is like waiting a lifetime,” said Marlowe. While acknowledging the sorry state of the current criminalistic approach to drug use, none of the panelists favored widespread drug legalization. It's a “bumper sticker solution to a complex problem,” O'Brien said. “Decriminalization is not such a straightforward answer,” Volkow said. O'Brien did predict that marijuana laws are likely to ease soon, but Volkow countered that while there is no evidence that marijuana is toxic to the developing brain, neither is there any that it is not toxic. “What are the consequences of messing with the cannabinoid system in adolescence?” she asked. “Our mission is to bring science to these questions,” she said, not to advocate for policies without enough evidence.

Neuroscientists on drugs

SfN participants say new understanding of addiction has had little effect on gov't policy

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