Abstract
Background:
Craving is attributed as one of the main reasons for relapse in alcohol dependence syndrome. Neurostimulation techniques targeting craving in substance use disorders are being researched. Neuroimaging has shown dorsolateral prefrontal cortex (DLPFC) as one of the potential targets responsible for craving, with frontal dysfunction being quintessential in alcohol use disorder. Evidence suggests that stimulation of DLPFC with low-dose current can help in reducing craving.
Objectives:
To study the effectiveness of transcranial direct current stimulation (tDCS) on craving in patients with alcohol dependence syndrome.
Materials and Methods:
We performed a single-blind, sham-controlled study involving 76 patients with alcohol dependence syndrome (according to ICD-10 DCR). Participants with Clinical Institute of Withdrawal Assessment in Alcohol Withdrawal (CIWA-Ar) scores less than 10, not on any anti-craving medications were included in the study. Patients were allocated to active and sham tDCS groups in a ratio of 1:1. Such that 38 patients received active, and 38 patients sham tDCS stimulations; with anode as right DLPFC and cathode as left DLPFC receiving 2 mA current (twice daily session, total of 10 sessions). The Alcohol Craving Questionnaire (ACQ-NOW) was administered to measure the severity of alcohol craving at baseline and after the last tDCS session.
Results:
Our study showed a significant reduction in craving in the Post-tDCS, ACQ-NOW scores as compared to sham tDCS. There was a significant reduction in the compulsivity and emotionality domain of craving after tDCS. The effect size for treatment with time interaction was (0.58).
Conclusions:
tDCS was superior to sham in reducing caving in patients with alcohol dependence syndrome.
Keywords: Alcohol dependence, craving, neuromodulation, tDCS
INTRODUCTION
Alcohol dependence is a major public health concern worldwide. It is responsible for almost 3.2% of all fatalities and a loss of 4% of all DALYs (58 million). In India, 62.5 million are alcohol consumers, with 17.4% of them (10.6 million) being dependent users, and 20%–30% of hospital admissions are due to alcohol-related problems.[1] The National Mental Health Survey of 2017 highlighted the treatment gap for alcohol dependence to be as high as 85%. Even when several treatment options are available, many patients have shown a chronic course of addiction. The abstinence rates range between 40% and 60% at 1 year post treatment.[2] Gowda et al. stated that around 65%–70% of abstinent alcohol-dependence subjects tend to relapse within 1 year, more within the first 3 months of abstinence.[3]
Craving is attributed as one of the main reasons for relapse into alcohol dependence. It is a multidimensional concept further defined in terms of behavioral, reinforcement, and cognitive processing. It is defined as the “pressing, urgent, and irrepressible desire to give in to the substance.”[4]
The gradual transition from occasional drug use to habitual use, impulsive act to compulsive behavior, and obtaining positive reinforcement (reward) to the loss of negative reinforcement coming from withdrawal is based on neuroadaptive changes in the brain.[5] Neuroplasticity in the basolateral amygdala, orbitofrontal cortex, dorsal striatum, and prefrontal cortex have primarily been associated with craving, and the dorsolateral prefrontal, inferior frontal cortices, and cingulate gyrus are involved in disrupted inhibitory control.
However, most studies suggest that it is the prefrontal region, especially the dorsolateral prefrontal cortex (DLPFC), which plays a major role in cravings pertaining to alcohol and smoking.[6,7]
Neurostimulation techniques with specific targeted interventions such as DLPFC modulation and improving cognitive control over alcohol intake can serve as an alternate treatment option.
Transcranial direct current stimulation (tDCS), a noninvasive brain stimulation technique in which a weak current is applied to the brain for several minutes through electrodes, results in “polarity-dependent modulation of the brain.”[8] It has been demonstrated in the past that modulation of the cortical excitability of the prefrontal cortex by application of tDCS can reduce craving and “cue-reactivity” for alcohol,[9,10,11] marijuana,[12] heroin,[13] and alcohol dependence.[10]
The pioneer studies carried out to assess the anti-craving effects of tDCS had limitations such as small sample size (e.g. Boggio et al., 2008 (N = 13)[9] and Den Uyl et al., 2015 (N = 41)),[14] less number of days of tDCS administration, and unilateral stimulation with the application of low-intensity current for a small duration. It is worth mentioning that discrepancies do exist as Den Uyl et al. found no significant reduction in craving, and the repetitive unilateral anodal tDCS over the left DLPFC was reported to increase relapses in alcohol dependence patients.[14]
The best available evidence suggests that anodal stimulation of right DLPFC and cathodal stimulation of left DLPFC reduces craving.[9]
This study was conducted in accordance with the tDCS protocol used in a recent study that examined the effects of multisession tDCS on craving and relapse in patients.[15]
MATERIALS AND METHODS
Participants
It was a single-blind sham-controlled study aimed at assessing craving in patients of alcohol dependence using tDCS, admitted to the psychiatry in-patient facility of a tertiary care hospital over a period of 1 year (January 2020–December 2020).
The sample consisted of 76 patients who satisfied the inclusion criteria and were hospitalized for 1 week. Patients who met the criteria for alcohol dependence (according to ICD10-DCR), in the age group of 18–60 years, and with a Clinical Institute of Withdrawal Assessment of Alcohol revised (CIWA-Ar) score of ≤10 were included in the study.
Patients with dependence on substances other than alcohol (except nicotine), patients receiving medications other than benzodiazepines, history of any other psychiatric illness or mental retardation, or history of any neurological disorder or electronic or metal implants that might interfere with stimulation were excluded. Institutional ethical approval was obtained prior to the study (MDC/DOME/298).
Patients who satisfied the inclusion criteria were explained in detail about tDCS, and informed written consent was taken for those who wished to participate. The details of those participants who satisfied the criteria but refused participation in the study were also recorded. Patients who wished to enroll in the study were allocated randomly into two groups, active and control, in a ratio of 1:1 [Flowchart 1].
Flowchart 1.
Flowchart of the study
Sampling
Each of the patients was randomized into two groups. Even numbers were allocated as active tDCS group and odd enrollment numbers as sham tDCS group. This went on till the sample size (76) was obtained. This sample size was obtained from a previous similar study[4] with an effect size of 0.58 considering alpha error as 0.10 and power as 0.80. Only the investigators knew about the two different groups. Participants were blinded regarding the same using the sham setting in the device.
A semi-structured proforma was used for recording sociodemographic details along with clinical data such as duration of alcohol use, amount of daily alcohol use, last intake, and history of any medical and psychiatric illness. It included details of the physical examination and mental status examination. The CIWA-Ar for withdrawal symptoms, the Severity of Alcohol Dependence Questionnaire Form-C (SADQ-C) to quantify the severity of alcohol dependence, and the Alcohol Craving Questionnaire (ACQ-NOW) for the estimation of craving at baseline level were applied.[16]
ACQ-NOW is a 47-item multidimensional scale that categorizes craving under four domains: compulsivity, expectancy, emotionality, and purposefulness. Each item is graded on a visual analog scale ranging from 0 (strongly disagree) to 8 (strongly agree).[13]
The questionnaire was translated into the local language following the WHO protocol for self-administration. The handedness preference schedule, Hindi Version (Mandal et al., 1992),[17] was applied for selecting right-handed patients.
The intervention-tDCS
tDCS is a noninvasive procedure that works on the principle of neuronal excitability through mild direct stimulation. Excitation is achieved by anodal stimulation, and inhibition is achieved by cathodal stimulation as the current flows from the anode to the cathode.[12] The strength of stimulation depends on the current intensity and duration and the surface area polarized. In this study, a tDCS - Soterix 1*1 low-intensity current device with sham controlled setting was used that generated current up to 2 mA. For electrodes, 5 × 5 EASYpads (sponge electrodes) were used along with headgear as rubber straps.
The device has a pre-tickle stimulation setting for sensitizing the patients prior to stimulation. The sessions were performed for 20 minutes with a fade-in and fade-out period of 30 seconds and a current intensity of 2 mA. These sessions were conducted twice a day (separated by at least 6 hours) for 5 days.
The active tDCS group received bilateral DLPFC stimulation for 20 minutes. The current intensity was set at 2 mA, the anode was placed over the right DLPFC (F4), and the cathode over the left DLPFC (F3). The right and left DLPFC were located using the 10–20 EEG system.
Sham tDCS group: The second group received sham tDCS with the same position of electrodes as described in the active group. However, in this setting, after 30 seconds of stimulation, the stimulator automatically gets switched off. It is primarily used to elicit sensations; direct current is not delivered. ACQ NOW was re-administered after the last tDCS session to observe the changes in alcohol craving in the individual.
Statistical analysis
The data were analyzed using statistical software (IBM SPSS Statistics for Windows, Version 26.0, IBM Corp., Armonk, NY, USA) with different parametric and nonparametric tests, as indicated. The study was powered assuming a two-sided test of group effect at α =0.05 significance level and at the 95% confidence level. Group differences for sample characteristics were examined using independent t test and Fisher’s exact test wherever applicable.
t test was used to compare the two groups at each timepoint. Paired sample t test was used to explore the difference in ACQ-NOW scores between the various timepoints within each group. The two-way repeated measures ANOVA method was used to explore the difference in change in ACQ-NOW scores between the two groups over time.
RESULTS
Baseline sociodemographic and clinical profile
The participants in both groups were comparable with respect to all demographic parameters [Table 1].
Table 1.
Comparison of sociodemographic profiles of the study sample
| Parameters | Group |
P | |
|---|---|---|---|
| Active tDCS (n=38) | Sham tDCS (n=38) | ||
| Age (years) | 37.55±8.47 | 36.58±8.86 | 0.4461 |
| Marital Status | 0.6132 | ||
| Married | 28 (73.7%) | 26 (68.4%) | |
| Unmarried | 10 (26.3%) | 12 (31.6%) | |
| Religion | 0.5673 | ||
| Hindu | 32 (84.2%) | 35 (92.1%) | |
| Christian | 4 (10.5%) | 2 (5.3%) | |
| Muslim | 2 (5.3%) | 1 (2.6%) | |
| SES | 0.1622 | ||
| Lower | 19 (50.0%) | 14 (36.8%) | |
| Middle | 10 (26.3%) | 18 (47.4%) | |
| Upper | 9 (23.7%) | 6 (15.8%) | |
| Education | 0.1543 | ||
| No formal education | 1 (2.6%) | 2 (5.3%) | |
| Primary | 14 (36.8%) | 18 (47.4%) | |
| Middle | 3 (7.9%) | 0 (0.0%) | |
| Intermediate | 3 (7.9%) | 0 (0.0%) | |
| Graduate | 17 (44.7%) | 18 (47.4%) | |
| Occupation*** | 0.0363 | ||
| Skilled | 25 (65.8%) | 23 (60.5%) | |
| Semi-skilled | 6 (15.8%) | 14 (36.8%) | |
| Unskilled | 6 (15.8%) | 1 (2.6%) | |
| Student | 1 (2.6%) | 0 (0.0%) | |
Clinical profile of the study sample
Both the active group and sham group had a similar clinical profile with respect to the age of onset of alcohol consumption, history of delirium or hospital admissions, CIWA scores, and SADQ scores [Table 2].
Table 2.
Clinical profile of the study sample
| Parameters | Group |
P | |
|---|---|---|---|
| Active (n=38) | Sham (n=38) | ||
| Total Years Of Consumption*** | 11.74±6.53 | 9.33±6.94 | 0.0481 |
| Age Of Onset (years) | 26.05±6.16 | 27.11±6.00 | 0.6721 |
| Comorbidities | 0.9643 | ||
| None | 27 (71.1%) | 25 (65.8%) | |
| Diabetes Mellitus | 6 (15.8%) | 5 (13.2%) | |
| Hypertension | 2 (5.3%) | 3 (7.9%) | |
| Others | 1 (2.6%) | 2 (5.3%) | |
| Hypothyroidism | 1 (2.6%) | 2 (5.3%) | |
| Diabetes + Hypertension | 1 (2.6%) | 1 (2.6%) | |
| Primary Form of Alcohol | 0.2263 | ||
| IMFL | 22 (57.9%) | 28 (73.7%) | |
| Beer | 15 (39.5%) | 10 (26.3%) | |
| CML | 1 (2.6%) | 0 (0.0%) | |
| Maximum Abstinence Period (Years) | 0.52±0.52 | 0.79±0.79 | 0.2341 |
| Past H/O Admission (Yes) | 20 (52.6%) | 18 (47.4%) | 0.6462 |
| H/O Delirium (Yes) | 10 (26.3%) | 16 (43.2%) | 0.1242 |
| CIWA Score | 1.26±1.27 | 1.29±1.14 | 0.7661 |
| Level Of Confidence | 0.1722 | ||
| No Confidence | 3 (7.9%) | 6 (15.8%) | |
| Little Confidant | 9 (23.7%) | 7 (18.4%) | |
| Moderately Confident | 7 (18.4%) | 12 (31.6%) | |
| Very Confident | 9 (23.7%) | 10 (26.3%) | |
| Extremely Confident | 10 (26.3%) | 3 (7.9%) | |
| SADQ | 0.1102 | ||
| Mild | 17 (44.7%) | 26 (68.4%) | |
| Moderate | 15 (39.5%) | 8 (21.1%) | |
| Severe | 6 (15.8%) | 4 (10.5%) | |
***Significant at P<0.05, 1: Wilcoxon–Mann–Whitney U test, 2: Chi-squared test, 3: Fisher’s exact test, 4: t-test IMFL (Indian-made foreign liquor)
The mean (SD) of total years of consumption was 11.74 (6.53) in the active group and 9.33 (6.94) in the sham group.
There was a significant difference between the two groups in terms of total years of consumption (W = 910.000, P = 0.048), with the median total years of consumption being the highest in the active group [Figure 1].
Figure 1.
The Box-and-Whisker plot depicts the distribution of total years of alcohol consumption in the groups. The middle horizontal line represents the median total years, the upper and lower bounds of the box represent the 75th and the 25th centile, respectively, and the upper and lower extent of the whiskers represent the Tukey limits for total years of consumption in each of the groups
The mean (SD) of the maximum abstinence period (years) in active and sham groups were 0.52 (0.52) and 0.79 (0.79), respectively. Twenty-six participants had a past history of delirium. As per ACQ NOW, “Levels of confidence,” that is, confidence to quit alcohol for 1 year, was also assessed.
Participants response varied from “Little confident” (21%) to “Very confident” (25%). Ten participants in the active group were extremely confident, whereas only three participants in the sham group reported being so. The dependence pattern was assessed using the SADQ scale as mild (52%), moderate (30.3%), and severe dependence (13%).
Treatment outcomes
Effect of tDCS in craving scores as measured by ACQ-NOW the Pre and Post (tDCS) Scores.
Baseline craving scores were compared in both groups, and no statistically significant difference was found between the groups in terms of ACQ-NOW: Total Score (Pre-tDCS) (P = 0.117) [Table 3].
Table 3.
Change in the mean ACQ-NOW scores with time in both groups
| Groups Mean (SD) |
P for comparison of the two groups at each of the timepoints (t-test) | Overall P for comparison of the change in ACQ-NOW: **(Generalized Estimating Equations) | ||
|---|---|---|---|---|
| Active | Sham | |||
| ACQ-NOW: Total Score* | ||||
| Pre-tDCS | 175.89 (32.75) | 163.13 (37.17) | 0.117 | 0.024* |
| Post-tDCS | 121.08 (31.11) | 126.63 (29.43) | 0.427 | |
| P Value for change in ACQ-NOW: Total Score over time within each group (Paired t-test) | <0.001 | <0.001 | ||
| ACQ-NOW: Compulsivity | ||||
| Pre-tDCS | 47.11 (10.80) | 45.37 (11.56) | 0.347 | 0.081 |
| Post-tDCS | 32.24 (10.95) | 34.82 (10.79) | 0.42 | |
| P Value for change in ACQ-NOW: Compulsivity over time within each group (Wilcoxon Test) | <0.001 | <0.001 | ||
| ACQ-NOW: Expectancy | ||||
| Pre-tDCS | 25.58 (5.95) | 24.58 (6.77) | 0.496 | 0.059 |
| Post-tDCS | 17.05 (5.57) | 18.61 (4.69) | 0.193 | |
| P Value for change in ACQ-NOW: Expectancy over time within each group (Paired t-test) | <0.001 | <0.001 | ||
| ACQ-NOW: Purposefulness* | ||||
| Pre-tDCS | 33.26 (8.82) | 28.32 (6.20) | 0.006 | 0.027* |
| Post-tDCS | 23.55 (6.26) | 22.16 (4.88) | 0.282 | |
| P Value for change in ACQ-NOW: Purposefulness over time within each group (Paired t-test) | <0.001 | <0.001 | ||
| ACQ-NOW: Emotionality | ||||
| Pre-tDCS | 10.34 (4.06) | 10.34 (3.30) | 1.000 | 0.058 |
| Post-tDCS | 7.08 (2.57) | 8.34 (2.75) | 0.042 | |
| P Value for change in ACQ-NOW: Emotionality over time within each group (Paired t-test) | <0.001 | <0.001 | ||
**Two-way repeated measures ANOVA was used to explore the difference in change in ACQ-NOW scores between the two groups over time ; *Significant at P<0.05
In the active tDCS group, the mean ACQ-NOW: Total Score decreased from a maximum of 175.89 at the Pre-tDCS timepoint to a minimum of 121.08 at the Post-tDCS timepoint. This change was statistically significant (Paired t test: t = 8.9, P = <0.001) [Figure 2].
Figure 2.
The following is a line diagram depicting the change in ACQ-NOW: Total Score and its different domains of craving over time in the two groups. In the group receiving active tDCS, the mean ACQ-NOW: Total Score decreased from a maximum of 175.89 at the Pre-tDCS timepoint to a minimum of 121.08 at the Post-tDCS timepoint. This change was statistically significant (Paired t-test: t=8.9, P=<0.001). In the Sham group, the mean ACQ-NOW: Total Score decreased from a maximum of 163.13 at the Pre-tDCS timepoint to a minimum of 126.63. This change was statistically significant (Paired t-test: t=6.7, P=<0.001). The overall change in ACQ-NOW: Total Score over time was compared in the two groups using the Generalized Estimating Equations method. There was a significant difference in the trend of ACQ-NOW: Total Score over time between the two groups (P=0.024)
In the sham tDCS, the mean ACQ-NOW: Total Score decreased from a maximum of 163.13 at the Pre-tDCS timepoint to a minimum of 126.63 at the Post-tDCS timepoint. This change was statistically significant (Paired t test: t = 6.7, P = <0.001). The two-way repeated measures ANOVA method was used to explore the difference in change in ACQ-NOW: Total Score between the two groups over time. The overall change over time was compared in the two groups by using generalized estimating equations. There was a statistically significant reduction in craving active group when compared to sham group after 10 tDCS sessions (P = 0.024) [Table 3].
The effect of tDCS in reducing craving in different domains was also studied in detail pre and post intervention with significant reductions in “Purposefulness” over time and was compared in the two groups by using generalized estimating equations (P = 0.027).
DISCUSSION
Craving is one of the main triggers for relapse in alcohol use disorder. Neurostimulation techniques such as tDCS have emerged as a novel treatment option. With specific targeted interventions such as DLPFC modulation and improving cognitive control, it has been shown to be useful in reducing craving in alcohol dependence. This study was conducted to explore the effect of tDCS on multidimensional aspects of craving. The measures to assess craving differ from one study to the other, as well as the number of participants and the process of stimulation. The tool used in this study to assess craving was ACQ NOW. This scale has been shown to correlate with other multidimensional measures and visual analogs used to monitor changes in levels of craving from pre-intervention through post-intervention.
As described in the results above, the reduction in total craving score post tDCS was significant. This result highlighted the point that polarity-dependent modulation of targeted brain areas such as the DLPFC can be significant in reducing craving pertaining to alcohol and thereby reducing relapse. This finding correlated with some of the important pioneer research done in this field.
The multidimensional aspect of craving is not limited to mere drug-seeking behavior but different domains as described in the ACQ-Now. “Compulsivity” is the urge and desire in anticipation of loss of control over drinking.[14] It is regulated by the orbitofrontal cortex. As hypothesized by Boggio et al.,[9] neuromodulation targeting DLPFC also co-activates the orbitofrontal and ventromedial cortex. The peculiarity of their study was that both strategies of DLPFC stimulation, that is, anodal left/cathodal right and anodal right/cathodal left stimulation, resulted in craving reduction.
However, the overall change in ACQ-NOW: Compulsivity over time was compared in the two groups Two-way repeated measures ANOVA revealed no significant difference (P = 0.081). The percent change in ACQ-NOW: Compulsivity scores was more significant in the active group than in the sham group (−30.22 ± 21.22 vs. −21.53 ± 18.33) (P = 0.037) [Table 4]. Similarly, other domains such as “Expectancy,” which is the urge and desire to drink in anticipation of the positive benefits of drinking, and “Emotionality,” which is the urge and desire to drink in anticipation of relief from withdrawal effect, did not yield significant differences when compared over time (P = 0.059 and 0.058, respectively) [Table 4].
Table 4.
Association between group and parameters (pre and post tDCS)
| ACQ-NOW SCORES | Active (n=38) | SHAM (n=38) | P |
|---|---|---|---|
| Percent Change in ACQ-NOW: Total Score*** | −29.54±18.85 | −20.57±15.67 | 0.0371 |
| Percent Change in ACQ-NOW: Compulsivity*** | −30.22±21.22 | −21.53±18.33 | 0.0371 |
| Percent Change in ACQ-NOW: Expectancy*** | −31.47±22.30 | −21.76±16.72 | 0.0354 |
| Percent Change in ACQ-NOW: Purposefulness | −26.51±20.03 | −20.18±14.90 | 0.2031 |
| Percent Change in ACQ-NOW: Emotionality*** | −25.83±25.79 | −14.81±28.97 | 0.0381 |
***Significant at P<0.05, 1: Wilcoxon–Mann–Whitney U test, 2: Chi-squared test, 3: Fisher’s exact test, 4: t-test
The findings reinstate the possibility of an increased number of stimulations and a follow-up assessment of these parameters of craving.
Purposefulness is “the urge and desire coupled with intent and planning to drink.”[14] It is regulated by the reward and emotional circuits of the brain. They take part in executive functions. Downregulation of dopamine signaling, which dulls the reward circuits’ sensitivity to pleasure, also occurs in prefrontal brain regions and associated circuits, impairing executive functions such as self-regulation, decision-making, action selection and initiation, and attribution of salience. After ten sessions of tDCS, there was a reduction in purposefulness in both groups [Table 3]. The mean scores decreased from a maximum of 33.26 at the Pre-tDCS timepoint to a minimum of 23.55 at the Post-tDCS timepoint (Paired t test: t = 7.3, P = <0.001) and for the sham group 28.32 at the Pre-tDCS to 22.16 at the Post-tDCS timepoint. This change was statistically significant (Paired t test: t = 6.5, P = <0.001). The overall change in ACQ-NOW: Purposefulness over time was compared in the two groups was significant (P = 0.027). It can be inferred that by targeting planning and execution, impulse associated with drug-seeking behavior and enhancing frontal lobe functions such as executive functions as stated before by da Silvia et al. (2013)[10]; tDCS reduces purposefulness associated with craving.
Based on these results, it can be concluded that tDCS reduces craving in alcohol dependence, specifically in those individuals who score high in the Purposefulness domain of craving.
The findings of the current study correlated with that of Boggio et al. (2008)[12] (n = 13, P < 0.0001).
However, both studies differed in their sample size along with assessment of craving. In another study conducted by Den Uyl et al. (2015),[16] it was found that there was significant reduction in craving in patients with alcohol dependence syndrome.
However, the number of sessions administered in their study was three, whereas in our study, we administered ten sessions. Another study conducted by Den Uyl et al. (2016)[11] also showed reduction in patients with alcohol dependence syndrome; however, their study sample included only hazardous drinkers. A study conducted by da Silvia, Mc, et al. (2013)[10] showed a reduction in craving in patients with alcohol dependence syndrome. However, tDCS stimulations were given unilaterally, whereas in our study, the stimulations were bilateral.
Adverse effects
In our study, the majority of the patients tolerated tDCS well. Two patients in the active group reported tingling and itching sensations with stimulation. Three (2 in the active and 1 in the sham group) patients reported headache, which subsided after giving analgesics. Our study findings were comparable to the side effects reported in a study conducted by Boggio et al. (2008),[9] where discomfort at the site of stimulation was the most common adverse effect (1 report in the sham and 2 reports in anodal left/cathodal right and anodal right/cathodal left stimulation conditions) followed by headache (1, 0, and 2 reports, respectively).
Through these findings, we can infer that tDCS is safe and well tolerated in patients.
STRENGTH
Our study had the advantage of having a larger sample size as compared to most previous studies. The number of sessions was also more (10 sessions) as compared to previous studies, which gave fewer sessions (ranging between 3 and 5 sessions). The target areas of stimulations were bilateral stimulation with a current intensity of 2 mA as compared to previous studies, where target stimulation areas were unilateral with a current intensity of 1 mA. The current study is also different in terms of the assessment of craving. Few studies have used cue-based (images), and some studies have also tried to incorporate frontal assessment battery (FAB). Our study used a self-rating questionnaire in which the participants themselves answered 47 questions pertaining to craving before and after tDCS. Given the relatively rapid suppressive effect of tDCS and the fluctuating nature of alcohol craving, tDCS can serve as a valuable treatment strategy.
Limitations
This was an in-patient study. The study findings cannot be generalized to out-patient or community settings. This study could have included more number of days or simulations, which could have elicited a stronger effect on craving. Our study was also limited by a lack of double-blinding and randomization.
CONCLUSION
The current study showed that tDCS is superior to placebo in reducing craving in patients of Alcohol dependence syndrome in in-patient settings. Out of the four domains of craving that were studied, purposefulness had a significant reduction in craving over time.
Abbreviations
DLPFC – Dorsolateral prefrontal cortex
tDCS – transcranial direct current stimulation
ACQ-NOW – Alcohol craving questionnaire
CIWA-Ar – Clinical Institute of Withdrawal Assessment of Alcohol revised.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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