Permanent changes in the brain due to methamphetamine use
Methamphetamine is a particularly dangerous drug, both during immediate use, for obvious reasons, but also in the long term. A recent study produced by the University of Washington and others, which was published in the April 10th issue of Neuron, used mice to look at the effects of methamphetamine on the brain. According to the researchers, methamphetamine depresses parts of the brain over time and this cannot be undone by abstinence. Specifically, the drug depressed terminals in the cortex and striatum that control the flow of information between these two areas of the brain. The drug actually causes permanent changes or adaptations in the brain to compensate for the continual release of dopamine. According to Nigel Bamford, M.D., “What we found is that the repeated use of methamphetamine causes adaptations in the brain, and that only re-introducing the drug can reverse that. We think these changes in the brain may account for at least some of the physiological components of meth addiction.” The following is an excerpt of an article from Medical News Today that reviews the study:
Scientists have believed that abuse of drugs like meth can cause changes to the neurons in the brain and the synapses and terminals that control transmission of information in the brain. In this project, researchers focused on the mouse brain, and how it was affected by methamphetamine over 10 days, which is the mouse equivalent of chronic use in humans.
They found that the long administration and withdrawal of the drug depressed the neural terminals controlling the flow of signals between two areas of the brain, the cortex and striatum. Even a long period of withdrawal — the equivalent of years in humans — did not return the terminals to normal activity level. Re-introducing the drug, however, reversed the changes in the brain.
The areas affected by the drug are called pre-synaptic terminals, and are related to the flow of information from the cortex to the striatum. When a person sees something new in their environment, the scientists explained, she focuses attention on that item. At the neuron level, that process stimulates the release of dopamine, a chemical involved in transmitting signals in the brain. As the person sees the new item over and over again, the dopamine response drops, and synapses in the brain adapt to the no-longer-new item.