NIDA supported research to prevent the spread of AIDS related to drug abuse is building on what has been learned from an array of prevention approaches that target specific populations and selected high risk drug- use and sexual practices. At the same time, basic research sponsored by the Institute is probing factors associated with the dual epidemics of AIDS and drug abuse, including the role of drug use in the rate of disease progression to AIDS following exposure to HIV, the human immunodeficiency virus, which causes AIDS.
Presentations at two recent NIDA conferences on AIDS and drug abuse reflect the profound role drug abuse plays in the spread of HIV. (See NIDA Plays Key Role in Studying Links Between AIDS and Drug Abuse," NIDA NOTES, May/June 1995) The conferences were held last summer in Scottsdale and Flagstaff, Arizona.
"We're learning what works for whom" in interventions to reduce the risk of infection with HIV, explains Dr. Richard H. Needle, chief of the Community Research Branch in NIDA's Division of Epidemiology and Prevention Research.
"The cumulative research literature can be examined for indications of progress," says Dr. Needle, whose branch helped sponsor the Flagstaff meeting. "Each individual study has strengths and limitations, but, collectively, generalizations can be drawn. We see where we have been effective and we learn how to be even more effective" in curtailing behaviors that put people at risk of contracting or transmitting HIV.
"These conferences were extremely useful in bringing researchers together, involving other agencies, and sharing important data that have not yet been published," says Dr. Harry W. Haverkos, director of NIDA's Office on AIDS, which sponsored the Scottsdale meeting.
Drug Injection and AIDS Prevention
One conference presentation examined "sociometric and personal networks" of street injecting drug users (IDUs). These risk networks consist of a limited number of core users whose network standing and prominence may influence drug use practices of others at the network fringes. The NIDA funded study queried 687 street recruited injecting drug users in New York City about their drug use and sexual behaviors. Researchers identified two network variables as significant predictors of HIV infection: being a core network member and having an older IDU in one's personal network.
Drs. S. R. Friedman and A. Neaigus of National Development and Research Institutes, Dr. D.C. Des Jarlais of Beth Israel Medical Center, and their colleagues in New York City concluded that future prevention efforts for street IDUs should target core network members and address factors leading to core group membership as well as injection practices among groups of users of different ages and experiences.
Among emerging intervention approaches are those that target groups with dual risks for acquiring HIV. Men who have sex with other men and also inject drugs engage in two high risk behaviors. They can serve as a "bridge" linking others who belong to one of these two high risk populations. In many western states, this dual risk category was identified in as many as 50 percent of HIV cases.
Programs are under way in Seattle, San Francisco, and Los Angeles to target this bridge population composed of both HIV-infected and uninfected persons. Innovative interventions to counsel, educate, and reduce behavioral risks are proving effective, according to several measures. They result in less needle sharing; reduced frequency of drug use; increased knowledge about unsafe sex practices, sexually transmitted diseases, and HIV; and improved compliance with tuberculosis and HIV medication regimens, according to a NIDA funded grantee, Dr. Michael Gorman of the University of Washington. Injecting drug using men who have sex with other men "represent a critical, hidden, heretofore underserved, poorly understood population" that can benefit from innovative public health prevention interventions, he reported.
A similar NIDA facilitated study describes HIV prevention interventions that target men who have sex with men and who use methamphetamine. HIV prevention efforts in Seattle, San Francisco, and Los Angeles cities with a high prevalence of AIDS among men who have sex with men and methamphetamine use are being studied.
Another analysis of Seattle's needle-exchange program examined IDUs who regularly pool their pocket money to buy drugs. The study found a link between pooling money for drugs and high risk practices like the sharing of needles and drug paraphernalia. "It may be worthwhile to target prevention efforts at this clustering of risk around the joint purchase of drugs," reported Dr. James McGough of the King County, Washington, Health Department.
Drug Abuse Treatment
Several studies and analyses presented at the two conferences further document the effectiveness of drug abuse treatment in reducing drug use, crime, and HIV infection.
Data on AIDS risk behaviors of some 10,000 drug abuse treatment clients from 1991 to 1993, collected by NIDA's Drug Abuse Treatment Outcome Study, were analyzed by Dr. Wendee M. Wechsberg and others of the Research Triangle Institute and NIDA. The patients, from 99 treatment programs, reported that behaviors putting them at risk of HIV infection needle sharing, sex with multiple partners, and unprotected sex were reduced somewhat during treatment. Researchers suggest this large scale survey validates findings of smaller studies, demonstrating the benefits of drug abuse treatment and emphasizing the importance of AIDS prevention interventions during treatment.
While drug abuse treatment is generally recognized as effective in reducing HIV risks among those in treatment, the impact of effective treatment extends beyond treated individuals and into their social networks, research indicates. Recent studies in the Philadelphia area suggest that treatment not only reduces the frequency of injection drug use but also changes patterns of use. Individuals in treatment report less injection drug use with strangers and acquaintances. There is a corresponding increase in the number of individuals who report always using drugs alone. Treatment thus has the effect of removing links in drug using networks and reducing the risk of spreading HIV through those networks. In reducing drug use with others, treatment's "role in tertiary prevention is significant and perhaps under appreciated," concluded Dr. Martin Y. Iguchi of the Medical College of Pennsylvania and Hahnemann University.
Basic Research on Drug Abuse and AIDS
A number of NIDA funded basic science investigations examining the relationship between drugs of abuse and the functions of the immune system were presented at the conferences.
Previous research had found evidence that drugs of abuse can suppress the immune system in laboratory animals. But scientists have not demonstrated the clinical impact in humans. It is, therefore, important to select and use appropriate laboratory animal models of HIV infection and progression patterns in humans.
Research by Dr. Lisa H. Gold and colleagues at the Scripps Research Institute demonstrates that neurobehavioral abnormalities in rhesus monkeys and cats infected with viruses similar to HIV (simian and feline immunodeficiency viruses) and in certain genetically engineered mice make these animals suitable experimental models for future studies of the interactions between drugs and HIV. Cognitive testing partially supported by NIDA, along with other neurological assessments, indicates that monkeys infected with the simian immunodeficiency virus undergo nervous system changes similar to those seen in HIV-infected human patients.
Another study examined the effects of morphine on the immune status and disease resistance of monkeys infected with the simian immunodeficiency virus. The study found that the effect of opiates on the immune system may be variably and conditionally dependent on whether the drug doses are long term and steady or sporadic, with sporadic dosing having less apparent effect. The NIDA supported study was conducted by Robert M. Donahoe and colleagues at Emory University and Dr. Mario Aceto of the Medical College of Virginia.
Evidence shows that opiates play a role in modulating HIV infection in the brain, according to another study by Dr. Chun C. Chao of the University of Minnesota and others. They found that an artificial compound called U50,488 that binds selectively to the kappa opioid receptor markedly suppresses HIV cell reproduction in the brain, where the deadly virus usually replicates.
Other AIDS and HIV Prevention Research
More than 100 oral presentations were given and scores of scientific abstracts were displayed at the NIDA conferences, including those with these findings:
- Although drug use itself was not found to be associated with mother-to-child HIV transmission in the women studied, drug users had poorer prenatal care, more adverse birth outcomes, and many clinical characteristics like increased rates of anemia, pneumonia, and smoking that may increase the possibility of HIV transmission to their newborns.
- Interventions with out-of-treatment heroin addicts are more successful when they include actual scheduling of treatment admission instead of simply distributing lists of treatment centers. This active referral results in higher treatment rates, and those persons entering treatment are more strongly associated with reduced drug use and less criminal activity.
- Research on community outreach for HIV prevention in mid-sized towns determined that adding two sessions to a "standard" office-based counseling program led to additional reductions in HIV risks in Flagstaff, Arizona, as reported by Dr. Robert Trotter of Northern Arizona University.