12/10/04
For the first time, scientists have seen exactly which brain areas in both chronic meth users and recovering meth addicts change. Paul Thompson, a University of California at Los Angeles brain researcher, used high-resolution MRI brain scans to compare the brains of 22 chronic meth users with those of 21 non-users.
Thompson told Discover Magazine that the MRI scans of addicts showed evidence of considerable brain inflammation and that two key brain areas associated with memory—the same ones damaged in early Alzheimer's—shrunk some 10 percent.
"One thing the drug users reported was loss of memory," he says. "They have poorer memory than people of the same age and the loss of tissue in the memory areas of the brain linked with this functional decline. So, people who lost most tissue in the memory areas actually had worse performance on tasks that involved memory."
That's not all. Thompson's colleague, Edythe London, a neuroscientist also at the University of California at Los Angeles, used PET scans—or positron emission tomography—to image how glucose is processed in the brains of 17 methamphetamine abusers who had stopped using the drug nearly a week before they participated in her study. She then compared those brain images with the brain images of 18 non-abusers, who completed the same attention task as their brains were measured.
"When people take crystal meth and become dependent on the drug, there is a real change in how the brain works," she says. "Very specifically, those circuits in the brain that are primarily in the pre-frontal cortex are down-regulated." The pre-frontal cortex is responsible for controlling behavior, but it also regulates an area in the lower brain—the amygdala—responsible for emotion. "The methamphetamine abuser, at least in early abstinence, has a pre-frontal cortex that's not doing its job of controlling the amygdala. So when the methamphetamine user is reminded of drug taking by being in a place where he or she took the drug before…or even the feeling of money in the pocket that could be used to take the drug, this turns on the amygdala and other areas of the brain that are important for craving."
Coupled with cranked-up craving is another danger, a depression so crushing the alternative—more meth—seems preferable. "There's an incredible manic high that's followed by this depression that feels like it's ripping me apart," Lee L. says.
This jumbled biochemical process helps explain in part why chronic crystal users have such a difficult time quitting, London says: "This really can color how they feel and make them want to take the drug again."
Worldwide, crystal meth use has reached epidemic proportions, Thompson warns: "It's a spreading problem and really the increase has to do with the availability of the drug…it's very easy to abuse and very easy to actually get this drug."
National Institutes of Health figures show that, for now, crystal meth use amongst teens stabilized in 2003 at 6.2 percent of high school seniors, unchanged from 6.9 percent in 2001. All told, 12.4 million Americans age 12 and older—or 5.3 percent of the population—had tried methamphetamine at least once by 2002, the National Survey on Drug Use and Health reported on the same NIH website.
Now that researchers know what's happening in the meth abuser's brain, teatment options might soon change, both London and Thompson agree. For starters, doctors could prescribe anti-depressants during the initial phases of recovery to get addicts over the depression hump, London suggests. The new information "is absolutely critical," she adds, if doctors want to "tailor make therapies for this brain as it changes and approaches recovery."
