When viewing a photo of an alcohol cue, people with alcohol use disorder experience a decrease in concentrations of the neurotransmitter glutamate in the brain, according to a study published online in Alcohol and Alcoholism.
“This is the first study to document changes in glutamate levels during exposure to alcohol cues in people with alcohol use disorders and shines a spotlight on glutamate levels as an important target for new therapies to treat the condition,” said Sharlene Newman, PhD, a professor in the department of psychological and brain sciences at Indiana University in Bloomington.
Researchers used magnetic resonance spectroscopy to gauge glutamate concentrations in 17 people with alcohol use disorder and 18 people without the disorder. When people with the disorder viewed a photo of alcohol in a glass or similar images associated with drinking, glutamate levels in the anterior cingulate cortex dropped, according to the study. Neutral photos had no such effect on participants, and participants without alcohol use disorder had no change in glutamate levels upon viewing any of the images.
Previous research has suggested sights and sounds linked with addictive substances affect glutamate levels in rats with addiction.
“Glutamate is the real workhorse of all transmitters in the brain," said George Rebec, PhD, professor emeritus in the department of psychological and brain sciences at Indiana University, who led the animal study. “Dopamine is the more popularly known neurotransmitter, a lack of which contributes to depression, anxiety, attention-deficit/hyperactivity disorder, and Parkinson's disease—but it actually accounts for less than 5% of all synaptic activity. By contrast, glutamate accounts for about 50% of this activity and is especially involved in the reward-motivation circuits integral to addiction.”
Added Dr. Newman, “Scientists can now confidently target glutamate levels in the brain as they develop new treatments for alcoholism and other forms of addiction.”