Multi-session electrical neuromodulation effects on craving, relapse and cognitive functions in cocaine use disorder: A randomized, sham-controlled tDCS study

Psychological factors predicting patients' risk of relapse after enrollment in drug use treatment: A systematic review

BACKGROUND AND AIMS

Despite high rates of relapse after treatment for drug use, to our knowledge there is no systematic literature identifying psychological factors that predict risk of relapse to drug use (excluding alcohol or tobacco). Our aim was to identify psychological factors that predict risk of relapse to drug use after enrollment in drug use treatment. The identification of such factors can support treatment planning and relapse prevention.

METHODS

We searched for peer-reviewed articles published between 2000 and 2023 in PsycINFO, PsycArticles, Web of Science, and PubMed. The inclusion criteria were: peer-reviewed publications, quantitative studies, in English, adult samples, with a prospective design, and analyses of minimum one psychological factor as predictor of relapse to drug use. All authors were involved in abstract and full-text screening, and in assessing risk of bias. The findings are presented in a narrative synthesis and tables are organized by type of drug.

RESULTS

Of 2226 publications initially identified, 45 were eligible. Twenty-three focused on predicting relapse to stimulants, 15 to opioids, and 7 to unspecified drugs. Substance use at baseline was an important factor predicting risk of relapse to opioids, and possibly stimulants. There was an indication that craving and attention problems potentially predict relapse to use of some drugs. Mental health factors (e.g., psychiatric diagnosis) did not predict relapse. Several psychological factors (e.g., cognition, emotion, personality, motivation) were scarcely examined. Over half of the studies had moderate to high risk of bias.

CONCLUSIONS

Based on the 45 studies, few psychological factors predicted risk of relapse to drug use. Higher comparability between studies and more rigorous methodology are necessary in order to derive more precise recommendations that inform and improve clinical practice.

PRE-REGISTRATION

PROSPERO, CRD42020182839.

A systematic review and meta-analysis of neuromodulation therapies for substance use disorders

While pharmacological, behavioral and psychosocial treatments are available for substance use disorders (SUDs), they are not always effective or well-tolerated. Neuromodulation (NM) methods, including repetitive transcranial magnetic stimulation (rTMS), transcranial direct current stimulation (tDCS) and deep brain stimulation (DBS) may address SUDs by targeting addiction neurocircuitry. We evaluated the efficacy of NM to improve behavioral outcomes in SUDs. A systematic literature search was performed on MEDLINE, PsychINFO, and PubMed databases and a list of search terms for four key concepts (SUD, rTMS, tDCS, DBS) was applied. Ninety-four studies were identified that examined the effects of rTMS, tDCS, and DBS on substance use outcomes (e.g., craving, consumption, and relapse) amongst individuals with SUDs including alcohol, tobacco, cannabis, stimulants, and opioids. Meta-analyses were performed for alcohol and tobacco studies using rTMS and tDCS. We found that rTMS reduced substance use and craving, as indicated by medium to large effect sizes (Hedge's g > 0.5). Results were most encouraging when multiple stimulation sessions were applied, and the left dorsolateral prefrontal cortex (DLPFC) was targeted. tDCS also produced medium effect sizes for drug use and craving, though they were highly variable and less robust than rTMS; right anodal DLPFC stimulation appeared to be most efficacious. DBS studies were typically small, uncontrolled studies, but showed promise in reducing misuse of multiple substances. NM may be promising for the treatment of SUDs. Future studies should determine underlying neural mechanisms of NM, and further evaluate extended treatment durations, accelerated administration protocols and long-term outcomes with biochemical verification of substance use.

Targeting cravings in substance addiction with transcranial direct current stimulation: insights from a meta-analysis of sham-controlled trials

Addiction is a substantial health concern; craving-the core symptom of addiction-is strongly associated with relapse. Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that reduces cravings by altering cortical excitability and connectivity in brain regions. This systematic review and meta-analysis was conducted (following the PRISMA guidelines) to evaluate the efficacy of tDCS in reducing cravings for substances. Our analysis included 43 randomized, sham-controlled trials involving 1,095 and 913 participants receiving tDCS and sham stimulation, respectively. We analyzed the changes in craving scores and found that tDCS led to a moderate reduction in cravings compared with the sham effects. This effect was particularly pronounced when bilateral stimulation was used, the anodal electrode was placed on the right dorsolateral prefrontal cortex, current intensities ranged from 1.5 to 2 mA, stimulation sessions lasted 20 minutes, and the electrodes size was ≥35 cm². Notably, tDCS effectively reduced cravings for opioids, methamphetamine, cocaine, and tobacco but not for alcohol or cannabis. Our findings indicate tDCS as a promising, noninvasive, and low-risk intervention for reducing cravings for opioids, methamphetamine, cocaine, and tobacco. Additional studies are warranted to refine stimulation parameters and evaluate the long-term efficacy of tDCS in managing substance cravings.

Can Contingency Management Solve the Problem of Adherence to Antiretroviral Therapy in Drug-Dependent Individuals?

Drug misuse among people living with HIV (human immunodeficiency virus) is associated with higher mortality. It is a frequently observed reason for treatment abandonment, with people who misuse drugs showing a 10 to 25 times higher risk of HIV than the general population. The authors conducted a systematic review and meta-analysis to assess the efficacy of contingency management (CM) to improve adherence to antiretroviral therapy in people living with HIV and substance use disorder (SUD). The inclusion criteria consisted of studies written in English, Italian, Spanish, German, and French; studies conducted with humans; and clinical trials that combined SUD treatment with CM for people living with HIV. Two hundred twenty-two articles were identified, five met all inclusion criteria, and three provided enough data to perform the meta-analysis. We considered treatment adherence by measuring the increase in the CD4 count as our primary outcome. We found a significant increase in treatment adherence in the patient group compared with the control groups during the intervention phase. Positive findings did not persist after the cessation of the incentives. The meta-analysis showed that the intervention improved patient adherence by 2.69 (95% confidence interval: [0.08, 0.51]; p = .007) compared with the control group during the intervention period. All short-term CM studies converged on a positive result for adherence to antiretroviral therapy.

The Effect of Transcranial Direct Current Stimulation (tDCS) on Cocaine Addiction: A Narrative Review

Cocaine addiction is a significant problem worldwide. The development of addiction involves a reward system, which consists of certain brain regions like the ventral tegmental area, nucleus accumbens, and prefrontal cortex. Currently, there are no approved medications for treating cocaine dependence, so researchers are actively searching for effective treatments that can impact the brain. One potential treatment under investigation is transcranial direct current stimulation (tDCS), a non-invasive method of stimulating the brain to modulate its activity. In this review, we explore the use of tDCS in treating cocaine addiction. We found nine relevant articles via a literature search, and the results indicate that applying tDCS to the right dorsolateral prefrontal cortex (DLPFC) holds promise for reducing drug cravings in individuals with cocaine addiction. The review also discusses the possible mechanisms by which tDCS works and provides recommendations for future research in this field.

Effects of Transcranial Electrical Stimulation on Gambling and Gaming: A Systematic Review of Studies on Healthy Controls, Participants with Gambling/Gaming Disorder, and Substance Use Disorder

Gambling disorder (GD) and internet gaming disorder (IGD) are formally recognized behavioral addictions with a rapidly growing prevalence and limited treatment options. Recently, transcranial electrical stimulation (tES) techniques have emerged as potentially promising interventions for improving treatment outcomes by ameliorating cognitive functions implicated in addictive behaviors. To systematize the current state of evidence and better understand whether and how tES can influence gambling and gaming-related cognitive processes, we conducted a PRISMA-guided systematic review of the literature, focusing on tES effects on gaming and gambling in a diverse range of population samples, including healthy participants, participants with GD and IGD, as well as participants with substance abuse addictions. Following the literature search in three bibliographic databases (PubMed, Web of Science, and Scopus), 40 publications were included in this review, with 26 conducted on healthy participants, 6 focusing on GD and IGD patients, and 8 including participants with other addictions. Most of the studies targeted the dorsolateral prefrontal cortex, using transcranial direct current stimulation (tDCS), and assessed the effects on cognition, using gaming and gambling computerized cognitive tasks measuring risk taking and decision making, e.g., balloon analogue risk task, Iowa gambling task, Cambridge gambling task, etc. The results indicated that tES could change gambling and gaming task performances and positively influence GD and IGD symptoms, with 70% of studies showing neuromodulatory effects. However, the results varied considerably depending on the stimulation parameters, sample characteristics, as well as outcome measures used. We discuss the sources of this variability and provide further directions for the use of tES in the context of GD and IGD treatment.

Transcranial direct current stimulation of the frontal-parietal-temporal brain areas reduces cigarette consumption in abstinent heroin users

Transcranial direct current stimulation (tDCS) has been demonstrated to modulate neural activity and related brain functions. In clinical studies, tDCS has been shown to reduce craving in various substance use disorders including cocaine, heroin and nicotine. Our previous report suggested that cathodal tDCS on the frontal-parietal-temporal (FPT) brain areas reduced cigarette consumption in moderate smokers. However, whether it is effective in smokers with history of drug use is unknown. This study investigated the effects of bilateral FPT areas cathodal tDCS on smokers with history of heroin use. 22 abstinent heroin users were recruited and randomly assigned to sham group and tDCS group. The sham group received 30 s tDCS treatment and tDCS group received normal tDCS (one trial of 20 min, 1 mA, cathodal electrodes were placed bilaterally on the FPT areas). The average of daily cigarettes consumption was recorded for the week before the tDCS and the following day after tDCS. In addition, pupil light reflex was measured right before and after tDCS treatment. One trial of tDCS stimulation significantly reduced daily cigarette consumption in smokers who had heroin use history. This reducing effect was also observed in heavy smokers. In addition, this effect on cigarette consumption lasted at least 48 h after the stimulation. Furthermore, it has been shown that opiates decrease pupillary size in humans, we found detectable changes of the dynamic pupil light reflex after bilateral tDCS stimulation. These findings suggest that FPT cathodal tDCS may be an effective approach to reduce cigarette craving in heroin users.