Newsletter readers working on the front lines in the battle against substance abuse are becoming more and more familiar with the blank stare displayed by recovering methamphetamine addicts. Sometimes called the “1000 mile stare” or “blank affect,” the empty look communicates the neurochemical disruption caused by repeated use of this powerful stimulant drug. Effecting dopamine, norepinehrine and serotonin networks, serial methamphetamine use can result in neurotransmitter depletion that leads to depression, withdrawal, anhedonia and sleep disruption. Further, it seems that chronic methamphetamine use can also lead to disruptions in the size and volume of gray-matter and white-matter in the brain.

With the continuing development of MRI technology, scientists have been able to better follow the sequence of events that occurs in the brains of methamphetamine abusers. Methamphetamine is a central nervous system stimulant drug that causes the release of dopamine, a monoamine and principal neurotransmitter in the sympathetic nervous system. Dopamine is neurotoxic; as a result there has been growing concern that excessive release of dopamine might lead to damage involving the nerve cells that are involved with its activity. In furtherance of the interests that scientists have had about this process, high-resolution MRI and computational brain mapping was employed in the analysis of the brains of 22 chronic methamphetamine users whose length of drug use averaged 10.5 years. A group of 21 people who had no history of drug abuse were used as controls in this study. The methamphetamine abusers were interviewed and examined by physicians, each met the criteria called for by DSM-IV. Cognitive function and other measurements of mood and thought processes were undertaken. Memory was also analyzed and measured.

MRI results showed that there were very noticeable gray-matter deficits in the area of the brain that includes the corpus callosum, cingulate gyrus and paralimbic belts. The cingulate area displayed the most noticeable change with an overall loss of gray matter volume that averaged 11.3%. The deficits were measured by comparing the test subject gray matter against the control subject gray matter. The Hippocampus was observed to have reduced volume, the average deficit there was 7.8 %. Interestingly, white matter volumes were 7% greater in the white matter of the methamphetamine users.

What does this all mean? White-matter and gray-matter are the types of nerve tissue that are found in our brains. Men and women have differing amounts of each, but the purpose of each type of matter is the same for both sexes. In the gray-matter there are structures that are critically involved with emotions, memory and behavior. The areas mentioned as being affected in the corpus callosum are involved to one degree or another with how we remember people and events in our lives. Deficits in gray matter may be associated with behavioral disturbances as well as a variety of mental illnesses. Violent or aggressive reactions to our environment are also regulated through some of the areas identified as having experienced volume changes. The hippocampus consists of circuitry that moves recent information and experiences into memory; this system decides what information and experiences you decide to keep in memory and that which is chosen to be forgotten or discarded.

White-matter differs from gray-matter in several ways; it all starts with the color though. As you can imagine, gray-matter appears light gray in color, white matter an off-white color. White matter is protected by an outer covering a sheath that extends over the nerve cell. Gray-matter and white-matter work together in a very complex relationship that shapes our personality. The increase in the volume of white-matter amongst methamphetamine using subjects is as interesting maybe as the volume loss is in gray-matter. The interaction between white-matter and gray-matter volume is not completely understood. It is clear that white-matter acts as a mechanism that integrates information and as a sort of switchboard that connects separate parts of the brain into a unified structure. The amphetamines have proven capabilities in elevating some aspects of cognitive function, somewhere hidden in the pharmacology of the amphetamines might be the explanation for the increased white-matter volume.

This study casts light on the insidious consequences of methamphetamine use. Concern about the long-term consequences for regular users of methamphetamine is warranted. The abnormal behavior and emotions that we often see with recovering chronic methamphetamine users may be tied to significant changes in brain anatomy. These types of studies underscore the need for better access to drug treatment and the development of better pharmacological therapeutics that can be brought to bear in the struggle to manage methamphetamine abuse.

Reproduced with permission from The MEDTOX® Journal