Microglial cells support brain health by attacking infectious agents and clearing away damaged neurons, but too much microglial activity can initiate a biochemical cascade that assaults healthy neurons. Chronic methamphetamine abuse precipitates just such neurodegeneration, says Dr. Jean Lud Cadet of the NIDA Intramural Research Program.
Dr. Cadet and colleagues used positron emission tomography to document more than double the levels of activated microglia in all brain areas examined in 12 former methamphetamine abusers compared with 12 nonabusers. A lesser degree of excess glial activation was related to longer abstinence from the drug, suggesting that the abnormality resolves gradually. Individuals who had remained methamphetamine-free for 2 years exhibited activation levels similar to those measured in nonabusers.
The Journal of Neuroscience 28(22):5756-5761, 2008. [Full Text (PDF, 184KB)]