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Vol. LIX, No. 17
August 24, 2007

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The Drug and Disease Risk
Changing Dynamics of HIV/AIDS Examined

  Dr. David Metzger discusses drug abuse and HIV.  
  Dr. David Metzger discusses drug abuse and HIV.  

As long as scientists have studied the HIV epidemic, they’ve been aware of the large role drug abuse plays in the spread of the virus. Recently, they have started to look more closely at a specific facet of drug abuse: the behavior that leads someone to risk both addiction and possible HIV infection. What do we know about why people take these risks and how does that knowledge help us understand the way the epidemic is changing?

These questions were at the core of “Drug Abuse and Risky Behaviors: The Evolving Dynamics of HIV/AIDS,” a recent 2-day forum sponsored by NIDA, with many other institutes collaborating.

The dynamics of the HIV epidemic have changed, said NIDA director Dr. Nora Volkow. Whereas initially, 30 percent of HIV cases resulted from injection drug use, more effective treatments for injection drug users lowered this percentage. Since these treatments were introduced, however, "there's been a new phase in the development of drug abuse and the HIV epidemic that has to do with the effects of acute drug intoxication on how people engage in behaviors they would otherwise not do."

Because less is known about this new phase, she said "this is a good point to try to assess our portfolio and determine new strategies that we can use to take advantage of new opportunities."

  Dr. Nora Volkow, director of NIDA, welcomes the audience to the forum, "Drug Abuse and Risky Behaviors: The Evolving Dynamics of HIV/AIDS."
  Dr. Nora Volkow, director of NIDA, welcomes the audience to the forum, "Drug Abuse and Risky Behaviors: The Evolving Dynamics of HIV/AIDS."
AIDS: 26 Years and Counting

To start the meeting, Dr. Anthony Fauci, director of NIAID, provided what he called an "historical blitz" of the HIV epidemic. He said that in June 1981, when he first saw an article in Mortality and Morbidity Weekly Report about chronic pneumonia in five gay men in Los Angeles, it "struck me, but didn't stop the day for me." Only a month later, when he read another report on cases of Kaposi's sarcoma and pneumocystis pneumonia in New York and San Francisco, "it became very clear to me that I would be changing my career."

Now, he explained, an estimated 39.5 million people are living with HIV, including 2.3 million children under 15 years old, and 90 percent of people with HIV are in the developing world. In 2006, approximately 4.3 million people became infected with the virus and 2.9 million people died of AIDS.

In the U.S., more than 1 million people are living with HIV, 25 percent of whom are unaware of their infection, Fauci said. "This is important because 65 percent of the new cases are being transmitted by people who do not know they are infected."

The good news in HIV/AIDS research is treatment. There are now more than 25 FDA-approved antiretroviral drugs. However, only about 28 percent of people in need of antiretDr. Nora Volkow, director of NIDA, welcomes the audience to the forum, "Drug Abuse and Risky Behaviors: The Evolving Dynamics of HIV/AIDS." roviral drugs in low and middle income countries are receiving treatment, which tells us "our most spectacular success in drug delivery can't keep up with the bottomless pit of people who need it," Fauci said. This is where prevention comes in.

To elaborate on this topic, Dr. David Metzger, a research associate professor and director of the HIV prevention research division at the University of Pennsylvania, discussed the impact of drug abuse treatment on HIV infection. Historically, research shows that people in drug treatment who remain in treatment "have much lower risk behavior and infections," he said.

And though "most people look at the data and think that injection drug users are the only drug users at risk of HIV infection," studies show that use of other drugs, including alcohol and amphetamines, also plays a role.

Drug treatment can prevent HIV infection, he explained, because effective treatment reduces the frequency of drug use, leading to fewer drug-related risk behaviors and to fewer new infections; because it leads to increased access to HIV treatment; and because being in drug treatment leads to increased adherence to HIV medications for those already infected, which in turn leads to lower rates of new infections.

  Dr. Gregory Berns discusses neuroeconomics.
  Dr. Gregory Berns discusses neuroeconomics.
The Brain on Drugs

One way of learning more about why people engage in the risky behaviors that lead to drug abuse and HIV infection is by looking at the brain. Dr. Gregory Berns, associate professor of psychiatry and behavioral sciences at Emory University School of Medicine, discussed a relatively new approach to studying decision-making: neuroeconomics.

Usually, when he says this word, "I get these puzzled looks," Berns explained. But by merging neuroscience and economics, researchers in this area aim to "learn how the brain makes decisions," he said. "In terms of risky decision-making, we can determine where this is coming from in the brain and what we can do about it."

He displayed a photo of a woman gleefully holding up a lottery ticket. "Now this woman is clearly happy with her decision," he said. "And this decision is questionable, right?"

Lottery tickets are a perfect example of risky decision-making, he explained. "We know what the odds of winning are. If you do the math, it still makes no sense to buy them. Well, lotteries wouldn't exist unless a lot of people bought tickets, so something else is going on."

  NIAID director Dr. Anthony Fauci gives an historical overview of the HIV epidemic.
  NIAID director Dr. Anthony Fauci gives an historical overview of the HIV epidemic.
In lottery ticket purchasing and in drug abuse, he said, "something changes between conscious evaluations and actual behavior." This is where neuroeconomics comes into the mix: trying to understand what happens biologically in the brain that predisposes people to do irrational things.

Berns explained that a key insight of neuroeconomics is that "people make decisions not by what happens to them, but by what they expect to happen." Knowing this, researchers have been using a specific kind of MRI to look at areas of the brain that become active when people expect something from a decision they make. Results show that whether a person is expecting a monetary award, tasty food or a social reward, the brain shows activity in the same place. "This is a big deal," Berns said. "Because whatever the thing people are expecting to get, the brain really does seem to convert it into a common currency."

These findings suggest promising approaches to using brain imaging to predict decisions, an area of research further explained by Dr. Martin Paulus, a professor in residence in the department of psychiatry at the University of California, San Diego. He discussed utilizing neuroimaging to predict high-risk behaviors in methamphetamine users, concluding that in early studies, MRI shows potential for predicting whether a former meth user will relapse.

An Ongoing Discussion

These speakers were just the start. Over 2 days, experts delved more deeply into drug treatment and HIV prevention; looked at drug abuse and HIV in relation to different racial groups and in studies of women and youth; and discussed HIV prevention in criminal justice populations, HIV testing and counseling policy and expanding testing and counseling into community settings.

Dr. Jacques Normand, director of NIDA's AIDS Research Program and moderator of the event, concluded by suggesting that participants work to sustain the discussion and interaction the conference initiated.

This is important because, as Fauci noted at the start, in the HIV epidemic much has been accomplished, but there is much yet to do. "History will judge us as a global society by how well we address the next 25 years of HIV/AIDS," he said, "as much as by what we have done in the first 25 years." NIH Record Icon

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