TUESDAY, April 5, 2005 (HealthDay News) -- Brain changes caused by long-term methamphetamine use may not be permanent, according to a new study from the University of California, Davis.
Previous research found that methamphetamine use causes abnormalities in areas of the brain associated with selective attention and with memory.
This new study included eight former methamphetamine users who hadn't used the drug for one to five years, as well as 16 former methamphetamine users who had abstained from use for between one to six months. A third group included 13 healthy, non-substance-abusing individuals.
Researchers used proton magnetic resonance spectroscopy (MRS) to measure special biomarkers in an area of the brain called the anterior cingulum cortex, associated with selective attention. The researchers measured levels of N-acetylaspartate (NAA) -- which is present only in neurons -- to gauge the amount of brain cell loss in study participants.
The UCD team also measured levels of choline (Cho), a substance generated by the creation of new membranes which the scientists believe may serve as "an ideal marker" to trace brain cell recovery.
According to the researchers, all the former methamphetamine users had abnormally low levels of NAA, indicating increased levels of brain cell death. In addition, NAA levels appeared to decline in relation to the amount of time a participant had abused methamphetamine.
NAA levels didn't "bounce back," either, when abusers kicked their habit, the researchers noted, with levels staying more or less the same years later.
However, former methamphetamine users who'd been off the drug for one to six months did show elevated Cho levels suggestive of neural growth, while those who'd been off the drug for one to five years had Cho levels equal to those of the healthy control group.
"In the early periods following methamphetamine exposure, the brain may undergo several processes leading to increased membrane turnover," the UCD team explained. "When drug exposure is terminated, adaptive changes occur, which may contribute to some degree of normalization of neuronal structure and function."
"The understanding of how the human brain can recover or partially recover as a function of the extended drug abstinence has important implications both for the neurobiology of addiction and substance abuse treatment," they add.
The findings appear in the April issue of the journal Archives of General Psychiatry.
The U.S. National Institute on Drug Abuse has more about methamphetamine.