Meth use among HIV-infected MSM poses multiple physical & behavioral problems

Scientists are closer to understanding why

Methamphetamine abuse has been an acknowledged problem among HIV-positive and at-risk men who have sex with men (MSM) since 2000. But there is still much HIV clinicians and researchers do not know about how it interacts with HIV to create greater physical and behavioral problems.

"Methamphetamine is a risk factor for contracting HIV," says William F. Maragos, MD, PhD, an associate professor at the University of Kentucky Medical Center in Lexington, KY.

"Meth use does disinhibit people, and it contributes to further promiscuous sexual behaviors," Maragos says.

MSM often use methamphetamines, which are part of the circuit drug or party drug culture. Those who do are considered high risk for HIV transmission because the drug is associated with a number of risk factors.

These risk factors include multiple partners, unprotected insertive and receptive anal sex, casual partners, decreased use of condoms, and prolonged sexual activity, says Shirley Semple, PhD, a project scientist with the University of California - San Diego.

"Historically, San Diego County has the highest rates of methamphetamine use in the general population, and meth has been popular in the MSM community in San Diego since the 1990's," Semple says.

In a recent study, Semple and co-investigators examined the relationship between meth use and impulsivity, and they found that MSM who had the highest levels of impulsivity also had the strongest relationship between intensity of meth use and total unprotected sex.1

"This whole concept of impulsivity is a promising, but underdeveloped target concept in HIV prevention research," Semple says. "This study suggests it's important and related to sexual risk and also to meth use."

But investigators can't answer questions about causation, and so more research, including studies involving developing and testing clinical intervention strategies, is needed, Semple adds.

What nearly a decade of research into the connection between methamphetamine use and at-risk MSM has demonstrated is that HIV clinicians need to screen patients for methamphetamine use and suggest treatment when necessary.

"Heavier meth users who are high in impulsivity have higher sexual risk behaviors," Semple says.

It would be helpful to screen patients for both methamphetamine use and impulsivity, which at high levels could indicate the patient has an impulse control disorder diagnosis, she adds.

"It's difficult for clinicians because meth use makes people seem like they're impulsive because they're high on the drug," Semple notes. "So does that mean they have an underlying personality trait? We don't know."

The University of California - San Diego has a sexual risk intervention for meth-using, HIV-infected MSM that was begun in 2000, Semple says.

"The primary goal of the intervention was to reduce sexual risk behaviors in this population of active meth users," she says. "We didn't try to change their drug use behavior."

The program has evolved, and now there's an intervention to teach participants how to manage urges and cravings for methamphetamines using cognitive behavioral therapy and technique, Semple says.

Semple was a co-author of the new EDGE study, which assessed the efficacy of a theory-based behavioral intervention for increasing safer sex behaviors among meth-using MSM who were HIV positive.1

The study found that the EDGE intervention, which involved eight sessions designed to reduce high-risk sexual behaviors of meth-using MSM, was superior to the control condition for increasing self-efficacy for condom use.2

Another study found that it isn't easy to identify and reach meth-using MSM in some regions of the country because of geographic and cultural obstacles.

Researchers, who looked at the characteristics of meth-using MSM in North Carolina, found that methamphetamine users were not part of demographic groups that Southeastern clinicians typically associate with the drug. For example, MSM who reported using methamphetamine were more likely to report having higher education and health insurance coverage.3

"We hear a lot about meth use in urban centers, but we're in a part of North Carolina that isn't quite urban," says Scott D. Rhodes, PhD, MPH, an associate professor at Wake Forest University's division of public health sciences/social sciences and health policy in Winston-Salem, NC.

"There are some misconceptions about who is your typical meth user, especially in the South," Rhodes notes.

Due to popular media depictions of meth labs, methamphetamine users typically are associated with abandoned house meth laboratories or housewives in trailer parks, he notes.

"Providers on some levels may not realize what potential users look like in the sense that these people have health insurance, decent incomes, and they're professionals," he adds. "So they think, 'I don't have to screen them.'"

The problem is that broad-scale, social marketing campaigns warning MSM about meth use are difficult to employ in the Southeast, Rhodes says.

"We don't have parts of town where gay men and women congregate or hang out," Rhodes says. "There are a few bars around, but there is no gay center."

While some researchers propose using the Internet to reach this at-risk group, it's less than ideal of a strategy, he says.

"I think not having a visible gay community is challenging, and requires us to think creatively about how to reach these men," Rhodes says.

"Create an environment conducive to disclosure," Rhodes suggests. "Don't make assumptions about sexual behavior or drug use behavior."

One potential strategy is to have HIV clinicians screen patients for meth use by asking both direct and indirect questions. For example, one indirect question could be to ask whether the man has mail-ordered Viagra, or another such drug.

Many MSM who use methamphetamines, which can enhance sexual desire, but makes it more difficult to achieve sexual satisfaction, also use an erectile dysfunction drug that they've been prescribed from a doctor or from an Internet source, Rhodes says.

"If you have a 25-year-old patient who you realize is buying drugs for treating erectile dysfunction, or if the patient is trying to get a prescription to one of those drugs from you, then there probably is something going on other than the patient's need for that drug," Rhodes explains.

While more behavioral studies are needed to fully understand the impact of methamphetamine use among MSM who are HIV infected, there also is a need for additional basic research about what methamphetamines do to the bodies of infected patients.

For instance, what investigators have not yet demonstrated is whether, and how, methamphetamine use results in increased infectivity in the brains of HIV patients, Maragos says.

"We don't know how that is, but there seems to be a somewhat larger [viral] burden in the brains of people who use methamphetamines," Maragos says.

Maragos' research involves looking at toxic HIV proteins, including the tat protein, which enhances the replication of the virus.

"The tat protein has a number of other interactions, and one of them is toxic to cell neurons," Maragos says.

"So there are several things that are very interesting about HIV and methamphetamine and/or tat, and that is they both affect the same area of the brain called the basal ganglia, which is the part of the brain that impacts Parkinson's disease," Maragos explains. "Also, they both involve free radical formation."

Investigators directly injected the tat protein into the basal ganglia of a rat, and after 24 hours, they exposed the rat to methamphetamine, Maragos says.

"We chose concentrations that alone were not toxic and did not cause any damage to this area of the brain," Maragos says. "But when given 24 hours apart, they cause 65 percent loss in the transmitter dopamine, which is an important transmitter in the basal ganglia."

This basic research may eventually answer why clinical studies have found that HIV-positive patients who abuse methamphetamines have increased deficits in their brain's metabolic processes, he adds.

"A lot of people who have HIV develop an HIV-associated dementia," Maragos says. "And people who are methamphetamine abusers tend to have more severe cognitive deficits, as well as an increased risk of these defects."

The goal is to clarify the mechanism of what's happening with tat and methamphetamine exposure, he notes.

"People have established the mechanism of meth toxicity, but we really don't know in detail what the tat is doing to make meth so much more toxic," Maragos says. "So we're looking at pathways that might prime the brain in such a way that nontoxic doses of methamphetamine become highly toxic."

For instance, investigators are looking closely at the effect tat has on dopamine compartmentalization of basal ganglia and transporter function, he adds.

"We've only demonstrated that there are some motor deficits due to this interaction of HIV and methamphetamine," Maragos explains. "That's not published and that's just motor deficits."

What has been published is evidence of an impact on cognitive behavior and higher cortical functions, and this could be what leads to increased risky behavior, Maragos says.

References

  1. Semple SJ, et al. Methamphetamine use, impulsivity, and sexual risk behavior among HIV-positive men who have sex with men. J Addictive Dis. 2007;25:105-114.
  2. Mausbach BT, et al. Efficacy of a behavioral intervention for increasing safer sex behaviors in HIV-positive MSM methamphetamine users: Results from the EDGE study. Drug & Alcohol Dependence. 2007;87:249-257.
  3. Rhodes SD, et al. Characteristics of a sample of men who have sex with men, recruited from gay bars and Internet chat rooms, who report methamphetamine use. AIDS Pat Care & STDs. 2007;21:575-583.