Auditory event-related potentials (P3) and cognitive changes induced by frontal direct current stimulation in alcoholics according to Lesch alcoholism typology

Abstract

Frontal lobe dysfunction is a hallmark of alcohol dependence. Recent studies have shown that a simple but powerful technique of cortical modulation--transcranial direct current stimulation (tDCS)--can induce significant cognitive changes. We therefore aimed to assess the clinical and electrophysiological (as indexed by P3) effects of tDCS of left dorsolateral prefrontal cortex (DLPFC) in different types of alcoholic patients according to Lesch's typology. We enrolled 49 alcoholic subjects, aged between 18 and 75 yr, during the subacute abstinence period to participate in this study. Subjects underwent event-related potential (ERP) registration of alcohol-related and neutral sounds before, during and after active tDCS (1 mA, 35 cm², during 10 min) or sham procedure in a counterbalanced and randomized order. Frontal assessment battery (FAB) and five items of the Obsessive Compulsive Drinking Scale were applied at the beginning and at the end of each experimental session. ERP analysis showed an increase in the mean amplitude of P3 associated with alcohol-related sounds after tDCS. This effect was not seen for neutral sounds. This change was more pronounced in Lesch IV alcoholics. Secondary exploratory analysis showed a significant improvement of FAB performance after active tDCS compared to sham tDCS in Lesch IV alcoholics only. We showed clinical and electrophysiological evidence of tDCS-induced frontal activity enhancement that was specific for Lesch IV alcoholics. Given that frontal dysfunction may contribute to the loss of control over drinking behaviour, local increase in frontal activity induced by tDCS might have a beneficial clinical impact in the future.

Transcranial Direct Current Stimulation: a potential novel treatment for alcohol addiction and abuse

“…Anodal left dlPFCwas also shown to improve executive functioning in Lesch Type IV (as seen by FAB scores). This shows that tDCS can improve cognition in Lesch Type IV alcoholics although no significant effect of tDCS was apparent on MMSE 18 . Efficacy and Safety of tDCS tDCS has been shown to successfully reduce craving and relapse rate besides improving the overall perception on life [17][18][19][20][21] when applied on DLPFC [41][42][43][44][45] .…”

“…This is suggestive of poor frontal lobe activity in alcoholic subjects 40 . In study comparing the different types of Lesch alcoholics, Lesch type IV seem to be more sensitive to effects of tDCS as it showed maximum increase in P3 amplitude on alcohol exposure than other Lesch types and in contrast to Lesch type II alcoholics that showed decrease in P3 amplitude 18 . Anodal left dlPFCwas also shown to improve executive functioning in Lesch Type IV (as seen by FAB scores).…”

“…Hence, craving to drugs may increase the activity in DLPFC through mesolimbic pathway 25 . Three studies were done to measure the effect on craving using anode placed over left DLPFC [17][18][19][20][21] . In only one study, right DLPFC anodal was also used 17 .…”

“…Increase in mean P3 amplitude was seen at Pz and Cz sites in Lesch's IV and decrease in Lesch's II at Pz sites. The study recruited less number of subjects and hence lack of power might explain lack of significant effect on other alcoholic types and lack of correlation between P3 and FAB in Lesch's IV group 18 . A randomized trial was done on Lesch's type IV alcohol-dependent patients (n= 13; sham tDCS = 7; tDCS treatment = 6) who also met DSM-IV criteria for alcohol dependence using cue-reactivity paradigm.…”

“…The effects of tDCS have been shown to last for some time -30-120 mins 13 even after the end of stimulation period 11,12 tDCS has been shown to be effective in ameliorating the signs and symptoms of various psychiatric disorders including major depressive disorder, schizophrenia, obsessive-compulsive disorder 14,15,16 . Very recently, interest has arisen in the potential effect of tDCSon addiction as it has also shown to be effective in reducing craving and relapse rate in people with alcoholic problems [17][18][19][20][21] . In this article, we would review studies done using tDCS in people with AUD.…”