This Is Your Brain on Speed
At the same time, researchers note that the drug use causes metabolism to slow down in other parts of the brain -- another feature seen in patients with Parkinson's disease.
Even more ominous: Three of the people examined in these studies had been off methamphetamine for 11 months or more -- but the researchers could find no evidence that this long period of abstinence had resulted in any recovery from the drug-induced brain damage.
In fact, lead researcher Nora D. Volkow, MD, tells WebMD she plans to follow those who participated in this study to see whether there is ever a point at which detoxification can reverse the damage.
Although methamphetamine is manufactured illegally, using many highly toxic ingredients, Volkow believes it is the drug itself that causes the problems and not any possible contaminants.
One characteristic of methamphetamine, she explains, is that it causes a massive increase in the production of dopamine in the brain, which sets off a chain of damaging events that eventually destroys parts of the brain cells where dopamine acts.
The damage isn't something that happens overnight, she believes -- after, for example, a single hit of methamphetamine.
Although the brain damage is profound, Volkow says it could be even worse, except for the fact that methamphetamine users generally smoke the drug -- either in a pipe like crack cocaine or mixed together with tobacco -- and they routinely smoke cigarettes as well.
"One of the [things] that's very important is that methamphetamine abusers smoke cigarettes -- and that's not a bad thing," says Volkow, who explains that nicotine has been found to protect brain cells in animal studies.
On the other hand, smoking methamphetamine (as opposed to taking it by mouth) delivers a higher dose of the drug to the brain.
At one time, methamphetamine taken by mouth was used to treat attention deficit hyperactivity disorder, or ADHD. Volkow says these recent studies raise a key issue.
"After seeing data like these, you have to ask whether taking methamphetamine at low doses by mouth [is damaging]. It's a very important question," she says.