Research Evidence

Transcranial Direct Current Stimulation (tDCS) for Mood Disorders, Alcohol and Drug Addiction: A Comprehensive Review

1. Introduction

Based upon a multitude of double-blind, placebo-controlled studies, Transcranial Direct Current Stimulation (tDCS) as a non-invasive neuromodulation technique has proven to be effective in the treatment of substance abuse disorders (SUD) (Vitor de Souza Brangioni,2018)(Martinotti,2019)(Coles,2018). By improving neuroplasticity, it also helps to alleviate symptoms associated with other behavioral issues such as depression, anxiety, and stress (Halko, 2011)(Gebodh, 2019)(Duke, 2024). This report compiles findings from multiple published studies to provide an in-depth understanding of how tDCS works, its efficacy, treatment duration, long-term effects, relapse rates and recent technological advancements.

2. Mechanisms of Action of tDCS

Transcranial Direct Current Stimulation works by delivering a low-intensity electrical current to specific areas of the brain through electrodes placed on the scalp (Gebodh, 2019). The primary mechanism involves modulation of neuronal excitability: anodal stimulation generally increases cortical excitability, while cathodal stimulation decreases it (Brunoni, 2012). This modulation can safely enhance synaptic plasticity, alter neurotransmitter release, and improve neural network connectivity (Bikson, 2016). 

In addiction treatment, tDCS typically targets regions like the dorsolateral prefrontal cortex (DLPFC) and the mesocorticolimbic pathway, which are associated with reward processing, impulse control, and decision-making (Li, 2022). A double blind, placebo-controlled cross over study used fMRI imaging to demonstrate that stimulation of the DLPFC alters large-scale brain network connectivity related to drug use cues (Soleimani, 2022).

A study using Positron Emission Tomography (PET)/Magnetic Resonance Imaging (MRI) to evaluate the effectiveness of HD-tDCS on migraines concluded that it improved clinical outcomes which may be, in part, facilitated by the increase in the endogenous μ-opiod receptor availability (DaSilva, 2023).

3. Efficacy of tDCS for Smoking, Alcohol and Drug Addiction

Smoking

Transcranial direct current stimulation (tDCS) of the dorsolateral prefrontal cortex (DLPFC) has been shown to modulate cognitive control circuits and improve the ability to resist smoking(Falcone, 2016). Research in both in daily and social smokers showed that 10 sessions of tDCS resulted in reduced craving and a significant decrease in the number of cigarette smoked in both groups compared to the sham group.(Hajloo, 2019). Another double-blind, placebo-controlled study demonstrated that 5 consecutive sessions of tDCS significantly reduced cigarette consumption up to 4-weeks post-intervention (Vitor de Souza Brangioni,2018).

Alcohol Addiction

A randomized placebo-controlled clinical trial, found that tDCS over the DLPFC reduced alcohol craving and consumption over a period of five weeks (Klauss, 2018). A systematic review and meta analysis demonstrated the positive effects of multiple sessions of tDCS protocols on reducing symptoms of alcohol use disorder including reducing alcohol craving (Kim, 2021a).

Drug Addiction

A decade ago it was learned that targeting the orbitofrontal cortex with tDCS reduced SUD and craving (Hone-Blanchet, 2015).  A more recent study demonstrated that multiple sessions of tDCS over several weeks significantly decreased opioid craving and use (Eskandari, 2019). A 2019 systematic review of Clinical Trials concluded that tDCS has therapeutic effects in treating addictions (Yadollahpour, 2019).

Similarly, multiple randomized, placebo-controlled studies have demonstrated that tDCS has been effective in reducing cravings for various substances including cocaine and methamphetamine,(Batista, 2015)(Alizadehgoradel, 2020).

4. Efficacy of tDCS as an adjunct to Medication Assisted Therapy (MAT)

A meta-analysis of twelve randomized, sham-controlled trials concluded that tDCS combined with MAT was more effective on depression score and response rate than MAT alone (Wang, 2021).

Another meta-analysis. determined that tDCS combined with MAT significantly reduced craving-related measures for Opioid use disorder relative to sham stimulation (Bormann, 2024).

A study in 2020 demonstrated that tDCS can be applied as a safe and effective technique to relieve mental disorders among patients receiving Methadone Maintenance Therapy; and that depression, anxiety, and stress of participants were significantly reduced after the seventh session (Sadeghi Bimorgh,, 2020).

A clinical trial the following year with methadone patients resulted in significant improvement in cognitive flexibility, planning, decision making, inhibitory control/selective attention and memory and concluded tDCS is an effective and complementary to MAT treatment for opioid use disorder (Mostafavi, 2021).

Craving and withdrawal decreased significantly among patients with opioid use disorder on buprenorphine-naloxone after 10 treatments over 5 consecutive days. Additionally, there were statistically significant reductions recorded for the Clinical Opiate Withdrawal Scale (COWS), the Desire for Drug Questionnaire (DDQ), the Obsessive-Compulsive Drug Use Scale (OCDUS) (Kumar, 2022a).

5 Efficacy of tDCS for mood disorders, including depression, schizophrenia and bipolar disorder

A double-blinded randomized clinical trial with pretest, posttest, and follow-up design concluded that medication, in combination with tDCS, can reduce the depressive symptoms and improve the executive function of people with Bipolar Disorder (Mardani, 2021b). 

Thirty patients with schizophrenia and medication-refractory auditory verbal hallucinations received 20 minutes of tDCS or sham stimulation twice a day for 5 consecutive days. Auditory verbal hallucinations were robustly reduced by tDCS relative to sham stimulation and the beneficial effect on hallucinations lasted for up to 3 months (Brunelin, 2014).

Bipolar patients who received the mood stabilizers lithium, sodium valproate, and carbamazepine plus tDCS showed improvement in problem-solving and emotional regulation (cognitive reappraisal) skills (Mardani, 2023).

A systematic review of tDCS treatments to alleviate symptoms and improve cognition in psychiatric disorders indicated beneficial clinical effects for major depressive disorder and show promise for schizophrenia and substance use disorder (Mondino, 2014).

6. Duration of Treatment and Long-term Effects

Treatment Duration

The duration and frequency of tDCS treatments vary, but evidence suggests that both single and multiple sessions can be effective (Kim, 2021) and that multiple sessions were well tolerated with no significant adverse events (Klauss, 2018). Repeated sessions over four weeks led to more sustained reductions in alcohol craving compared to single sessions (Klauss, 2018). Similarly, a double-blind placebo-controlled study in 2019 found that a regimen of 10 sessions over two weeks significantly improved outcomes for individuals with substance use disorders (Martinotti, 2019).

Long-term Effects

The long-term effects of tDCS have been promising, though results can vary. A longevity study found that the beneficial effects of tDCS on alcohol craving and consumption were maintained at four-month follow-up (Camchong, 2023). However; some studies have noted that while initial reductions in craving are significant, long-term maintenance may require additional booster sessions (Kim, 2021a).

7. Relapse Rates and Comparative Effectiveness

Relapse Rates

Drug craving is a major problem in addiction treatment. When treating methamphetamine addicts, a single session of tDCS increased cognitive inhibition significantly however multiple treatments are required to develop abstinence (Rezvanian, 2022).

A 2020 randomized placebo-controlled study published in the journal Drug and Alcohol Dependence stated that, “promising results were obtained regarding relapse rates among crack-cocaine users” (Verveer, 2020). The results of a recent longitudinal double-blind placebo-controlled clinical trial demonstrated that tDCS“has an effect on addiction networks supporting abstinence and on relapse rates (Camchong, 2023).

Comparative Effectiveness

When comparing tDCS to other treatment modalities, it often serves as a valuable adjunct. In 2021 a randomized placebo-controlled trial found that combining tDCS with cognitive behavioral therapy (CBT) resulted in better outcomes than CBT alone for treating alcohol addiction (Dubuson, 2021). Similarly, another randomized placebo-controlled trial the same year reported that tDCS combined with CBT showed enhanced efficacy in reducing methamphetamine cravings compared to either modality alone (Xu, 2021).

8. Technological Advances

In traditional tDCS, large foam pads are placed on the head and up to a 2 mA current is applied for up to 20 minutes (Gebodh, 2019).  Although these treatments have been shown to be efficacious, a common complaint regarding the short comings of this modality is the lack of precision (Brunoni, 2012).  High Definition transcranial Direct Current Stimulation (HD-tDCS) has been recently introduced to improve the spatial accuracy of conventional tDCS, by using arrays of smaller, ‘high-definition electrodes’, instead of the two large pad electrodes (To, 2016). This allows for greater accuracy in treating specific brain areas.  

Traditional tDCS technology is a popular means of improving neural plasticity, and a recent study comparing it with HD-tDCS, emphasized that this is an important step to upgrade, refine and optimize the delivery of tDCS (Pellegrini, 2021). Additionally a 2021 study demonstrated HD-tDCS can induce more predictable outcomes than conventional tDCS (Masina, 2021). 

The Neural Science Institute has gone a step further with the Pathfinder Neural Pathway Therapy device.  Prior to any application of current, an EEG is taken on specific points, if necessary a short pulse is applied to the sensor measuring the lowest output.  Another EEG is taken and additional short pulses are applied until there is a measurable change.  Once the brain responds with a changed measurement, the sensors are moved to another position.  Multiple protocols of specific montages have been developed to address a variety of conditions.

9. Conclusion

Transcranial Direct Current Stimulation (tDCS) presents a promising intervention for treating mood disorders and SUD.  Its mechanisms involve modulating neural activity in key brain regions associated with addiction. Evidence from multiple studies supports its efficacy in reducing cravings and consumption, and HD-tDCS has been shown to be even more efficacious (Masina, 2021).  A meta analyses of studies using tDCS for SUD showed the individuals could not enjoy the substance anymore; and thus, recurrence was inhibited (Çabuk, 2024).

Long-term maintenance of these effects may require ongoing or booster sessions. While relapse rates post-treatment are variable, and improved by booster sessions, tDCS shows potential as an adjunctive therapy, enhancing outcomes when combined with other treatment modalities (Dubuson, 2021). 

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