Combined Brain Effects of Methamphetamine and HIV

Combined Brain Effects of Methamphetamine and HIV

Methamphetamine use has been shown in studies to be associated with high-risk sexual behavior. Habitual use of the street drug is subsequently associated with an increase in the risks for infection with the human immunodeficiency virus or HIV. On their own, methamphetamine and HIV can produce changes in brain function that significantly impair a wide range of processes responsible for conscious thought and other key aspects of mental awareness. In methamphetamine users who are positive for HIV, the combined effects of drug abuse and infection commonly produce greater degrees of brain dysfunction than either methamphetamine or HIV produce on their own.


In addition to its ability to produce heightened levels of the intense emotional state called euphoria, methamphetamine typically produces an increase in sexual libido. Since it appears in combination with a number of other meth-related mind-altering effects – including unusual aggressiveness and mood swings – this libido increase can easily lead to willing participation in such risky forms of sexual behavior as unprotected sex and multiple sexual partners with unknown disease histories. In fact, substantial numbers of meth users (typically men) take the drug specifically for its libido- and performance-enhancing effects. As a result of these factors, as well as methamphetamine’s ability to damage the immune system, meth users develop HIV infections much more frequently than the general public.

Methamphetamine’s Brain Effects

Habitual meth use damages the brain by producing long-term changes in the production of two key brain chemicals called dopamine and serotonin. Under normal circumstances, dopamine plays essential roles that include controlling activity in the brain’s reward/pleasure circuitry and regulating coordinated body movement. Serotonin plays such essential roles as maintaining a stable mood, regulating sleep cycles and influencing the ability to learn. In addition to its effects on these chemicals, methamphetamine circulating in the brain can kill off the organ’s main nerve cells, called neurons. It can also damage a blood vessel network called the blood-brain barrier, which helps protect the brain from infection.

The long-term presence of methamphetamine damages structures throughout the brain. Aspects of normal mental function that suffer as a result of this damage include the ability to make and recall memories, the ability to learn or retain new information, the ability to engage in acts of higher-level reasoning or abstract thinking, the ability to concentrate or sustain attention, and the ability to integrate conscious thoughts and commands with body balance or muscle control.

HIV’s Brain Effects

If left unchecked, the presence of HIV will eventually lead to the onset of acquired immune deficiency syndrome (AIDS), an advanced form of dysfunction characterized by immune system collapse and a greatly increased susceptibility to normally harmless microorganisms. However, well before the arrival of AIDS, the presence of HIV in the brain leads to a decline in function that closely mimics the types of mental dysfunction produced by chronic methamphetamine use. Generally speaking, the virus doesn’t cause damage by attacking the brain’s neurons. Instead, HIV apparently damages cells in the brain called glial cells that support neurons structurally and provide them with nutrients. In turn, HIV-compromised glial cells and immune system cells release toxins and other substances that damage the neurons.

Combined Effects

In a study published in 2005 in the journal Neurology,  researchers from UC San Diego measured the brain effects of meth use in people who were HIV-free, the brain effects of HIV in people who didn’t use methamphetamine, and the combined brain effects of methamphetamine and HIV. The common unit of measurement for estimating these effects was the outcome of a neuropsychological test called the global deficit score, or GDS.

The UCSD researchers concluded that, on its own, HIV infection in the average individual produces slightly more brain dysfunction than chronic meth use produces on its own (0.54 on the GDS for HIV, versus 0.52 for methamphetamine). However, HIV positive people who use methamphetamine have an average GDS of 0.65. In real-world terms, this means that while significant brain impairment occurs in about  37 percent of people who only have HIV or only use meth, 53 percent of HIV-positive meth users have significant brain impairment. For comparison, about 20 percent of people who didn’t have HIV and didn’t use methamphetamine had signs of impairment on a GDS test.

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