How Meth Destroys The Body - PBS

View an audio slideshow of the science behind the effects of meth on the brain with Dr. Richard Rawson of UCLA's Integrated Substance Abuse Programs.

Meth and the Brain

• Meth releases a surge of dopamine, causing an intense rush of pleasure or prolonged sense of euphoria.
• Over time, meth destroys dopamine receptors, making it impossible to feel pleasure.
• Although these pleasure centers can heal over time, research suggests that damage to users' cognitive abilities may be permanent.
• Chronic abuse can lead to psychotic behavior, including paranoia, insomnia, anxiety, extreme aggression, delusions and hallucinations, and even death.

"There [are] a whole variety of reasons to try methamphetamine," explains Dr. Richard Rawson, associate director of UCLA's Integrated Substance Abuse Programs. "[H]owever, once they take the drug … their reasons are pretty much the same: They like how it affects their brain[s]." Meth users have described this feeling as a sudden rush of pleasure lasting for several minutes, followed by a euphoric high that lasts between six and 12 hours, and it is the result of drug causing the brain to release excessive amounts of the chemical dopamine, a neurotransmitter that controls pleasure. All drugs of abuse cause the release of dopamine, even alcohol and nicotine, explains Rawson, "[But] methamphetamine produces the mother of all dopamine releases."

For example, in lab experiments done on animals, sex causes dopamine levels to jump from 100 to 200 units, and cocaine causes them to spike to 350 units. "[With] methamphetamine you get a release from the base level to about 1,250 units, something that's about 12 times as much of a release of dopamine as you get from food and sex and other pleasurable activities," Rawson says. "This really doesn't occur from any normally rewarding activity. That's one of the reasons why people, when they take methamphetamine, report having this euphoric [feeling] that's unlike anything they've ever experienced." Then, when the drug wears off, users experience profound depression and feel the need to keep taking the drug to avoid the crash.

Brain scan images from Dr. Volkow's study. Image copyright Nora Volkow/American Journal of Psychiatry.

When addicts use meth over and over again, the drug actually changes their brain chemistry, destroying the wiring in the brain's pleasure centers and making it increasingly impossible to experience any pleasure at all. Although studies have shown that these tissues can regrow over time, the process can take years, and the repair may never be complete. A paper published by Dr. Nora Volkow, director of the National Institute on Drug Abuse, examines brain scans of several meth abusers who, after 14 months of abstinence from the drug, have regrown most of their damaged dopamine receptors; however, they showed no improvement in the cognitive abilities damaged by the drug. After more than a year's sobriety, these former meth users still showed severe impairment in memory, judgment and motor coordination, similar to symptoms seen in individuals suffering from Parkinson's Disease.

In addition to affecting cognitive abilities, these changes in brain chemistry can lead to disturbing, even violent behavior. Meth, like all stimulants, causes the brain to release high doses of adrenaline, the body's "fight or flight" mechanism, inducing anxiety, wakefulness and intensely focused attention, called "tweaking." When users are tweaking, they exhibit hyperactive and obsessive behavior, as journalist Thea Singer's sister Candy did on her meth binges. "When she was high, which was almost always, she had to be on the computer -- diddling with programs to make them run faster, ordering freebies on the Internet," writes Singer. "Then computers faded, and she was obsessed with diving into dumpsters -- rescuing audio equipment from behind Radio Shack, pens from behind Office Depot." Heavy, chronic usage can also prompt psychotic behavior, such as paranoia, aggression, hallucinations and delusions. Some users have been known to feel insects crawling beneath their skin. "He picks and picks and picks at himself, like there are bugs inside his face," the mother of one meth addict told The Spokesman-Review. "He tears his clothes off and ties them around his head." The same article told the story of another former addict, who, even after five years of sobriety, can't go to the bathroom without propping a space heater against the door, in case someone is after him.