Tuesday, August 14, 2007

Zap the Brain to cut Alcohol Craving

Scientists at Harvard and in Brazil have just published a study that shows using low voltage current delivered through a pair of saline-soaked sponges to specific sites on the head can cut down an alcoholics craving for alcohol.

Prefrontal cortex modulation using transcranial DC stimulation reduces alcohol craving: A double-blind, sham-controlled study.

Previously studies have shown that high-frequency rTMS over the dorsolateral prefrontal cortex (DLPFC) can cut down smoking and cocaine craving. They postulated that by using tDCS to apply "subthreshold neuronal membrane depolarization" as a result of electrical current flow they could mimic the effects of rTMS. They had previously shown that tDCS delivered to both sides of the brain could reduce the craving for smoking and a craving for alcohol has been shown to increase activity in the DLPFC, so they juiced up some volunteers.

The study design was double-blind, sham-controlled, cross-over study that stimulated the brain using two mirror-image montages: one placed the active anode over the left DLPFC and the one that placed it over the right. The third was a sham control. They used validated scales to measure alcohol craving as well as side-effect questionnaires for tDCS. 13 subjects were examined at baseline and then went through the different protocols. The stimulation used 2mA for 20 minutes. They were shown videos, both before stimulation or sham stimulation, as well as after, that exposed them to alcohol cues for five minutes. After the exposure they were questioned about their craving for alcohol.

After the subjects were exposed to alcohol cues there was an 8% increase in their craving. There was a decrease in cravings after both left and right anode stimulation of 20-27%! To make things even more interesting cravings could not be increased by alcohol cues after the stimulation with active electrodes but it could be increased in the sham group.

Their conclusion is that "...both anodal left/cathodal right and anodal right/cathodal left DLPFC stimulation significantly decreased craving as compared to sham stimulation." They then go on to suggest the possible mechanisms for the changes including alteration of activity in the dopamine pathways.

"One potential advantage of developing tDCS as an alternative therapeutic strategy is the fact that the effects of tDCS are immediate.""...a single treatment that can transiently block craving levels quickly would be highly desirable compared to drug treatment therapies that are typically more long-lasting and lead to tonic effects and thus can-not capture craving variations."

Side-effects were very mild.