11 April 2006 

Crystal meth and HIV: Twin toxins for the brain

According to researchers in the United States, methamphetamine, or crystal meth (meth), is one of the most commonly abused street drugs among people with HIV and people at high risk for HIV infection.

Meth is toxic to brain cells. And HIV infection produces proteins that are also damaging to the brain. So, a team of neuroscientists at the University of California at San Diego wanted to find out if meth’s brain-damaging properties were enhanced as a result of HIV infection, particularly in people with very weakened immune systems.

Researchers found that meth addiction was linked to problems with memory and thinking clearly (neuro-cognitive impairment). These problems were most severe in people who had less than 200 CD4+ cells.

Study details
The team enrolled 284 HIV positive people, some of whom were addicted to meth and others who were not. None of the participants were dependent on alcohol, cocaine or other street drugs. However, researchers did not exclude people who were using marijuana.

The profile of the HIV positive participants (the focus of our report) is as follows:

  • 6% female, 94% male
  • average age – 38 years
  • CD4+ cell counts ranged between 50 and 635 cells
  • only 60% of participants who had less than 200 CD4+ cells were on anti-HIV therapy
  • on average, participants had been using meth for about 12 years

The research team gave participants neuropsychological tests that helped to assess concentration, memory, ability to process information, learning and intellectual functioning. Ultimately, the test results revealed the level of cognitive impairment.

Researchers found that participants who had less than 200 CD4+ cells or who were addicted to meth were significantly likely to suffer from cognitive impairment. Indeed, for all participants, the lower the CD4+ count, the greater the degree of cognitive impairment. And meth addiction made this worse.

These findings linking meth addiction to weakened immunity in HIV confirm previous research by other teams.

Researchers are not sure precisely how the combination of meth and HIV produces such a disturbing result. Preliminary results from other research teams suggest that meth enhances HIV neuro-toxicity and vice versa. Proteins from HIV and meth appear to damage the energy-producing parts of brain cells—the mitochondria—causing these cells to malfunction and die. Understanding the effects of meth is important so that scientists can hopefully find ways to reverse the brain damage that it causes.

Implications for addiction recovery and HIV treatment
The findings from this study underscore the need for increased support for HIV positive meth users trying to escape the downward spiral of life with meth. People with such a high degree of neuro-cognitive damage may have difficulty learning and maintaining the skills necessary to escape addiction and seek proper treatment and care.

Another impact of neuro-cognitive impairment is that it may affect users’ ability to adhere to anti-HIV therapy. In this study, 60% of participants who had less than 200 CD4+ cells—a level that puts them at high risk for life-threatening infections—were not on anti-HIV therapy. The reasons for this are not clear, but the research team speculated that perhaps participants’ health care providers were leery of prescribing therapy to people at high risk for experiencing non-adherence, treatment failure or drug interactions.

Possible solutions
The study team suggested that PHAs who are meth users or who appear to be suffering from cognitive impairment be referred to a psychologist for an evaluation. This would help to develop strategies to compensate for the loss of cognitive function and enhance their ability to recover from addiction and adhere to anti-HIV therapy. Education about meth’s devasting impact also needs to be enhanced.

—Sean R. Hosein


1. Carey CL, Woods SP, Rippeth JD, et al. Additive deleterious effects of methamphetamine dependence and immunosuppression on neuropsychological functioning in HIV infection. AIDS and Behaviour 2006; in press.

2. In SW, Son EW, Rhee DK, et al. Methamphetamine administration produces immunomodulation in mice. Journal of Toxicology and Environmental Health part A. 2005;68(23-24):2133-45.