Efficacy and acceptability of transcranial direct current stimulation (tDCS) for major depressive disorder: An individual patient data meta-analysis

Insights into interoceptive and emotional processing: Lessons from studies on insular HD-tDCS

Interoception, the processing of internal bodily signals, is proposed as the fundamental mechanism underlying emotional experiences. Interoceptive and emotional processing appear distorted in psychiatric disorders. However, our understanding of the neural structures involved in both processes remains limited. To explore the feasibility of enhancing interoception and emotion, we conducted two studies using high-definition transcranial direct current stimulation (HD-tDCS) applied to the right anterior insula. In study one, we compared the effects of anodal HD-tDCS and sham tDCS on interoceptive abilities (sensibility, confidence, accuracy, emotional evaluation) in 52 healthy subjects. Study two additionally included physical activation through ergometer cycling at the beginning of HD-tDCS and examined changes in interoceptive and emotional processing in 39 healthy adults. In both studies, HD-tDCS was applied in a single-blind cross-over online design with two separate sessions. Study one yielded no significant effects of HD-tDCS on interoceptive dimensions. In study two, significant improvements in interoceptive sensibility and confidence were observed over time with physical preactivation, while no differential effects were found between sham and insula stimulation. The expected enhancement of interoceptive and emotional processing following insula stimulation was not observed. We conclude that HD-tDCS targeting the insula does not consistently increase interoceptive or emotional variables. The observed increase in interoceptive sensibility may be attributed to the activation of the interoceptive network through physical activity or training effects. Future research on HD-tDCS involving interoceptive network structures could benefit from protocols targeting larger regions within the network, rather than focusing solely on insula stimulation.

Repeated prefrontal tDCS for improving mental health and cognitive deficits in multiple sclerosis: a randomized, double-blind, parallel-group study

BACKGROUND

Multiple Sclerosis (MS) is an autoimmune disease associated with physical disability, psychological impairment, and cognitive dysfunctions. Consequently, the disease burden is substantial, and treatment choices are limited. In this randomized, double-blind study, we conducted repeated prefrontal electrical stimulation in 40 patients with MS to evaluate mental health variables (quality of life, sleep difficulties, psychological distress) and cognitive dysfunctions (psychomotor speed, working memory, attention/vigilance), marking it as the third largest sample size tDCS research conducted in MS to date.

METHODS

The patients were randomly assigned (block randomization method) to two groups of sham (n = 20), or 1.5-mA (n = 20) transcranial direct current stimulation (tDCS) targeting the left dorsolateral prefrontal cortex (F3) and right frontopolar cortex (Fp2) with anodal and cathodal stimulation respectively (electrode size: 25 cm2). The treatment included 10 sessions of 20 min of stimulation delivered every other day. Outcome measures were MS quality of life, sleep quality, psychological distress, and performance on a neuropsychological test battery dedicated to cognitive dysfunctions in MS (psychomotor speed, working memory, and attention). All outcome measures were evaluated at the pre-intervention and post-intervention assessments. Both patients and technicians delivering the stimulation were unaware of the type of stimulation being used.

RESULTS

Repeated prefrontal real tDCS significantly improved quality of life and reduced sleep difficulties and psychological distress compared to the sham group. It, furthermore, improved psychomotor speed, attention, and vigilance compared to the sham protocol. Improvement in mental health outcome variables and cognitive outperformance were interrelated and could predict each other.

CONCLUSIONS

Repeated prefrontal and frontopolar tDCS ameliorates secondary clinical symptoms related to mental health and results in beneficial cognitive effects in patients with MS. These results support applying prefrontal tDCS in larger trials for improving mental health and cognitive dysfunctions in MS.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT06401928.

Non-invasive temporal interference brain stimulation reduces preference on morphine-induced conditioned place preference in rats

Long-term use of opioid drugs such as morphine can induce addiction in the central nervous system through dysregulation of the reward system of the brain. Deep brain stimulation (DBS) is a non-pharmacological technique capable of attenuating behavioral responses associated with opioid drug consumption and possesses the capability to selectively activate and target localized brain regions with a high spatial resolution. However, long-term implantation of electrodes in brain tissue may limit the effectiveness of DBS due to changes in impedance, position, and shape of the tip of the stimulation electrode and the risk of infection of nerve tissue around the implanted electrode. The main objective of the current study is to evaluate the effect of temporal interference (TI) brain stimulation on addictive behaviors of morphine-induced conditioned place preference (CPP) in rats. TI stimulation is a non-invasive technique used transcranially to modulate neural activity within targeted brain regions. It involves applying two high-frequency currents with slightly different frequencies, resulting in interference and targeted stimulation of different brain areas with the desired spatial resolution. The results indicated that TI stimulation with the amplitude ofI 1 = I 2 = 0.5 mA, carrier frequency of 2 kHz, frequency difference of 25 Hz, ON-OFF stimulation frequency of 0.25 Hz, and total duration of 10 min in three consecutive days resulted in a significant reduction of morphine preference in the morphine-stimulation group in comparison with the morphine group (p < 0.001). These findings highlight the potential of TI stimulation as a modulatory intervention in mitigating the addictive properties of morphine and provide valuable insights into the therapeutic implications of this stimulation paradigm for treatment of opioid drugs in human subjects.

Should rTMS be considered a first-line treatment for major depressive episodes in adults?

Treatment-resistant depression (TRD) is an epidemic with rising social, economic, and political costs. In a patient whose major depressive episode (MDE) persists through an adequate antidepressant trial, insurance companies often cover alternative treatments which may include repetitive transcranial magnetic stimulation (rTMS). RTMS is an FDA-cleared neuromodulation technique for TRD which is safe, efficacious, noninvasive, and well-tolerated. Recent developments in the optimization of rTMS algorithms and targeting have increased the efficacy of rTMS in treating depression, improved the clinical convenience of these treatments, and decreased the cost of a course of rTMS. In this opinion paper, we make a case for why conventional FDA-cleared rTMS should be considered as a first-line treatment for all adult MDEs. RTMS is compared to other first-line treatments including psychotherapy and SSRIs. These observations suggest that rTMS has similar efficacy, fewer side-effects, lower risk of serious adverse events, comparable compliance, the potential for more rapid relief, and cost-effectiveness. This suggestion, however, would be strengthened by further research with an emphasis on treatment-naive subjects in their first depressive episode, and trials directly contrasting rTMS with SSRIs or psychotherapy.

Home-based, Remotely Supervised, 6-Week tDCS in Patients With Both MCI and Depression: A Randomized Double-Blind Placebo-Controlled Trial

As depressive symptom is considered a prodrome, a risk factor for progression from mild cognitive impairment (MCI) to dementia, improving depressive symptoms should be considered a clinical priority in patients with MCI undergoing transcranial direct current stimulation (tDCS) intervention. We aimed to comprehensively evaluate the efficacy of the home-based and remotely monitored tDCS in patients with both MCI and depression, by integrating cognitive, psychological, and electrophysiological indicators. In a 6-week, randomized, double blind, and sham-controlled study, 37 community-dwelling patients were randomly assigned to either an active or a sham stimulation group, and received 30 home-based sessions of 2 mA tDCS for 30 min with the anode located over the left and cathode over the right dorsolateral prefrontal cortex. We measured depressive symptoms, neurocognitive function, and resting-state electroencephalography. In terms of effects of both depressive symptoms and cognitive functions, active tDCS was not significantly different from sham tDCS. However, compared to sham stimulation, active tDCS decreased and increased the activation of delta and beta frequencies, respectively. Moreover, the increase in beta activity was correlated with the cognitive enhancement only in the active group. It was not possible to reach a definitive conclusion regarding the efficacy of tDCS on depression and cognition in patients with both MCI and depression. Nevertheless, the relationship between the changes of electrophysiology and cognitive performance suggests potential neuroplasticity enhancement implicated in cognitive processes by tDCS.

Home-based transcranial direct current stimulation in bipolar depression: an open-label treatment study of clinical outcomes, acceptability and adverse events

BACKGROUND

Current treatments for bipolar depression have limited effectiveness, tolerability and acceptability. Transcranial direct current stimulation (tDCS) is a novel non-invasive brain stimulation method that has demonstrated treatment efficacy for major depressive episodes. tDCS is portable, safe, and individuals like having sessions at home. We developed a home-based protocol with real-time remote supervision. In the present study, we have examined the clinical outcomes, acceptability and feasibility of home-based tDCS treatment in bipolar depression.

RESULTS

Participants were 44 individuals with bipolar disorder (31 women), mean age 47.27 ± 12.89 years, in current depressive episode of at least moderate severity (mean Montgomery Asberg Depression Rating Scale (MADRS) score 24.59 ± 2.64). tDCS was provided in bilateral frontal montage, F3 anode, F4 cathode, 2 mA, for 30 min, in a 6-week trial, for total 21 sessions, a follow up visit was conducted 5 months from baseline. Participants maintained their current treatment (psychotherapy, antidepressant or mood stabilising medication) or maintained being medication-free. A research team member was present by video conference at each session. 93.2% participants (n = 41) completed the 6-week treatment and 72.7% of participants (n = 32) completed the 5 month follow up. There was a significant improvement in depressive symptoms following treatment (mean MADRS 8.77 ± 5.37) which was maintained at the 5 month follow up (mean MADRS 10.86 ± 6.90), rate of clinical response was 77.3% (MADRS improvement of 50% or greater from baseline), and rate of clinical remission was 47.7% (MADRS rating of 9 or less). Acceptability was endorsed as "very acceptable" or "quite acceptable" by all participants. No participants developed mania or hypomania.

CONCLUSIONS

In summary, home-based tDCS with real-time supervision was associated with significant clinical improvements and high acceptability in bipolar depression. Due to the open-label design, efficacy findings are preliminary.

TRIAL REGISTRATION

ClinicalTrials.gov number NCT05436613 registered on 23 June 2022 https//www.

CLINICALTRIALS

gov/study/NCT05436613.

Independent effects of transcranial direct current stimulation and social influence on pain

ABSTRACT

Transcranial direct current stimulation (tDCS) is a noninvasive neuromodulatory technique with the potential to provide pain relief. However, tDCS effects on pain are variable across existing studies, possibly related to differences in stimulation protocols and expectancy effects. We investigated the independent and joint effects of contralateral motor cortex tDCS (anodal vs cathodal) and socially induced expectations (analgesia vs hyperalgesia) about tDCS on thermal pain. We employed a double-blind, randomized 2 × 2 factorial cross-over design, with 5 sessions per participant on separate days. After calibration in Session 1, Sessions 2 to 5 crossed anodal or cathodal tDCS (20 minutes 2 mA) with socially induced analgesic or hyperalgesic expectations, with 6 to 7 days between the sessions. The social manipulation involved videos of previous "participants" (confederates) describing tDCS as inducing a low-pain state ("analgesic expectancy") or hypersensitivity to sensation ("hyperalgesic expectancy"). Anodal tDCS reduced pain compared with cathodal stimulation (F(1,19.9) = 19.53, P < 0.001, Cohen d = 0.86) and analgesic expectancy reduced pain compared with hyperalgesic expectancy (F(1,19.8) = 5.62, P = 0.027, Cohen d = 0.56). There was no significant interaction between tDCS and social expectations. Effects of social suggestions were related to expectations, whereas tDCS effects were unrelated to expectancies. The observed additive effects provide novel evidence that tDCS and socially induced expectations operate through independent processes. They extend clinical tDCS studies by showing tDCS effects on controlled nociceptive pain independent of expectancy effects. In addition, they show that social suggestions about neurostimulation effects can elicit potent placebo effects.

The effect of warm-up with transcranial direct current stimulation on performance factors in collegiate golfers

PURPOSE

This study aimed to determine the effects of warm-up using transcranial direct current stimulation (tDCS) on performance factors in collegiate golfers and to provide a scientific basis for the effectiveness and methodology of tDCS. We sought to compare the effects of tDCS as an additional treatment during warm-up. tDCS is generally activated when a small electric current is applied to the motor cortex of the cerebral cortex, which has been reported to be helpful in improving motor function. Therefore, we sought to prove the effectiveness of combined warm-up exercise and tDCS.

METHODS

Twenty-two collegiate male golfers were divided into tDC- (tDCS; n=11) and sham-treated (sham; n=11) groups. To examine performance factors, the following were assessed following tDCS application: carry, clubhead speed (CHS), ball speed (BS) for driver performance, countermovement jump (CMJ) for lower extremity muscle power, global rating of change (GRC) for the subjective change in condition of the participants, and test of attentional interpersonal style (TAIS) for concentration.

RESULTS

This study showed that warm-up with tDCS had positive effects on carry (p=.004), CHS (p=.019), BS (p=.017) of driver performance, CMJ (p=.002), and GRC (p=.005), however, no significant effect on TAIS was found, which suggest that the effects of the warm-up with tDCS were significant for driver performances, CMJ, and GRC.

CONCLUSION

Future studies should independently validate the effectiveness of tDCS and apply it to different situations and timeframes, such as training and competitions, to provide new alternative strategies or performance improvement.

Effectiveness and tolerability of adjunctive transcranial direct current stimulation (tDCS) in management of treatment-resistant depression: A retrospective chart review

Background

There is a limited number of studies from India investigating the role of transcranial direct current stimulation (tDCS) in treatment-resistant depression (TRD). This clinic-based study reports on the effectiveness of tDCS as an add-on treatment in individuals suffering from TRD.

Materials and Methods

Twenty-six right-handed individuals suffering from major depressive disorder who failed to respond to adequate trials of at least two antidepressant drugs in the current episode received tDCS as an augmenting treatment. Twice daily sessions of conventional tDCS were given providing anodal stimulation at the left dorsolateral prefrontal cortex (DLPFC) and cathodal placement at the right DLPFC. A total of 20 sessions were given over 2 weeks. The outcome was assessed based on changes in scores of the Hamilton Rating Scale for Depression (HAMD) and Montgomery-Asberg Depression Rating Scale (MADRS).

Results

There was a significant reduction in outcome assessment after tDCS intervention as compared to baseline, with more than 50% of the participants showing response in both scales, which increased further to approximately 77% by the end of 1 month of the follow-up period.

Conclusion

Twice daily tDCS sessions with anodal stimulation of left DLPFC and cathodal stimulation of right DLPFC is an effective add-on treatment strategy in individuals with TRD.

Quantitative analysis of noninvasive deep temporal interference stimulation: A simulation and experimental study

Background

Deep brain stimulation (DBS) is a method for stimulating deep regions of the brain for the treatment of various neurological and psychiatric disorders such as depression, obsessive-compulsive disorder, addiction, and Parkinson's disease. Generally, DBS can be performed using both invasive and non-invasive approaches. Invasive DBS is associated with several problems, including intracranial bleeding, infection, and changes in the position of the electrode tip. Temporal interference (TI) stimulation is a non-invasive technique used to stimulate deep regions of the brain by applying two high-frequency sinusoidal currents with slightly different frequencies.

New method

This paper presents insights into the response of the spiking in the Hodgkin-Huxley (HH) neuron model of the rat somatosensory cortex by changing the parameters carrier frequency, current ratio, and difference frequency of TI stimulation. Furthermore, in order to experimentally evaluate the effect of TI stimulation on the activation of the left motor cortex, an experiment was conducted to measure the motion induced by the balanced and unbalanced TI stimulation. In the experiment, a three-axis accelerometer was attached to the right hand of the animal to determine the position of the hand.

Results

Simulation results of the HH model showed that the frequency of the envelope of the TI stimulation is identical to the fundamental frequency of the neuron spikes. This result was obtained for difference frequencies of 6 Hz and 9 Hz in balanced and unbalanced TI stimulations. Moreover specifically, when the difference frequency is set to zero, the carrier frequency is within the range of 1300-1400 Hz, and the current range is between 140 and 250 μA/cm2, the firing rate reached to its highest value. In the experimental result, the maximum range of movement at a difference frequency of Δf = 6 Hz was approximately 1.6 mm and 5.3 mm in the z and y directions respectively.

Comparison with existing method

The results of the spatial spectrum of the rat hand movement were consistent with the spectrum information of the simulation results. Additionally, steering the interfering region to the left motor cortex leads to noticeable contralateral movement of the right hand while no movement was observed in the right hand during the stimulation of the right motor cortex.

Conclusion

This technique of stimulation for the deep regions of the brain is a promising tool to noninvasively treat various neurological and psychiatric disorders such as morphine dependence in addicted rats.

Accelerated transcranial magnetic stimulation for psychological distress in advanced cancer: A phase 2a feasibility and preliminary efficacy clinical trial

BACKGROUND

Psychological and existential suffering affects many people with advanced illness, and current therapeutic options have limited effectiveness. Repetitive transcranial magnetic stimulation (rTMS) is a safe and effective therapy for refractory depression, but no previous study has used rTMS to treat psychological or existential distress in the palliative setting.

AIM

To determine whether a 5-day course of "accelerated" rTMS is feasible and can improve psychological and/or existential distress in a palliative care setting.

DESIGN

Open-label, single arm, feasibility, and preliminary efficacy study of intermittent theta-burst stimulation to the left dorsolateral prefrontal cortex, 600 pulses/session, 8 sessions/day (once per hour) for 5 days. The outcomes were the rates of recruitment, completion of intervention, and follow-up (Feasibility); and the proportion of participants achieving 50% improvement on the Hamilton Depression Rating Scale (HDRS) or Hospital Anxiety and Depression Scale (HADS) 2 weeks post-treatment (Preliminary Efficacy).

SETTING/PARTICIPANTS

Adults admitted to our academic Palliative Care Unit with advanced illness, life expectancy >1 month and psychological distress.

RESULTS

Due to COVID-19 pandemic-related interruptions, a total of nine participants were enrolled between August 2021 and April 2023. Two withdrew before starting rTMS, one stopped due to clinical deterioration unrelated to rTMS, and six completed the rTMS treatment. Five of six participants had a >50% improvement in HDRS, HADS-Anxiety, or both between baseline and the 2 week follow up; the sixth died prior to the 2-week follow-up. In this small sample, mean depression scores decreased from baseline to 2 weeks post-treatment (HDRS 18 vs 7, p = 0.03). Side effects of rTMS included transient mild scalp discomfort.

CONCLUSIONS

Accelerated rTMS improved symptoms of depression, anxiety, or both in this small feasibility and preliminary efficacy study. A larger, sham-controlled study is warranted to determine whether rTMS could be an effective, acceptable, and scalable treatment in the palliative setting.

TRIAL REGISTRATION

NCT04257227.

Home-Use Transcranial Direct Current Stimulation for the Treatment of a Major Depressive Episode: A Randomized Clinical Trial

Importance

Transcranial direct current stimulation (tDCS) is moderately effective for depression when applied by trained staff. It is not known whether self-applied tDCS, combined or not with a digital psychological intervention, is also effective.

Objective

To determine whether fully unsupervised home-use tDCS, combined with a digital psychological intervention or digital placebo, is effective for a major depressive episode.

Design, Setting, and Participants

This was a double-blinded, sham-controlled, randomized clinical trial with 3 arms: (1) home-use tDCS plus a digital psychological intervention (double active); (2) home-use tDCS plus digital placebo (tDCS only), and (3) sham home-use tDCS plus digital placebo (double sham). The study was conducted between April 2021 and October 2022 at participants' homes and at Instituto de Psiquiatria do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Brazil. Included participants were aged 18 to 59 years with major depression and a Hamilton Depression Rating Scale, 17-item version (HDRS-17), score above 16, a minimum of 8 years of education, and access to a smartphone and internet at home. Exclusion criteria were other psychiatric disorders, except for anxiety; neurologic or clinical disorders; and tDCS contraindications.

Interventions

tDCS was administered in 2-mA, 30-minute prefrontal sessions for 15 consecutive weekdays (1-mA, 90-second duration for sham) and twice-weekly sessions for 3 weeks. The digital intervention consisted of 46 sessions based on behavioral therapy. Digital placebo was internet browsing.

Main Outcomes and Measures

Change in HDRS-17 score at week 6.

Results

Of 837 volunteers screened, 210 participants were enrolled (180 [86%] female; mean [SD] age, 38.9 [9.3] years) and allocated to double active (n = 64), tDCS only (n = 73), or double sham (n = 73). Of the 210 participants enrolled, 199 finished the trial. Linear mixed-effects models did not reveal statistically significant group differences in treatment by time interactions for HDRS-17 scores, and the estimated effect sizes between groups were as follows: double active vs tDCS only (Cohen d, 0.05; 95% CI, -0.48 to 0.58; P = .86), double active vs double sham (Cohen d, -0.20; 95% CI, -0.73 to 0.34; P = .47), and tDCS only vs double sham (Cohen d, -0.25; 95% CI, -0.76 to 0.27; P = .35). Skin redness and heat or burning sensations were more frequent in the double active and tDCS only groups. One nonfatal suicide attempt occurred in the tDCS only group.

Conclusions and Relevance

Unsupervised home-use tDCS combined with a digital psychological intervention or digital placebo was not found to be superior to sham for treatment of a major depressive episode in this trial.

Trial Registration

ClinicalTrials.gov Identifier: NCT04889976.

Efficacy of transcranial direct current stimulation for treating anhedonia in patients with depression: A randomized, double-blind, sham-controlled clinical trial

BACKGROUND

Anhedonia, the core symptom of major depressive disorder (MDD), is highly prevalent in patients with depression. Anhedonia is associated with low efficacy of drug treatment, high suicide rates, and poor social function. Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technology that uses constant, low-intensity direct current to treat MDD by regulating cortical activity and neuronal excitability. However, little is known about the efficacy of tDCS for treating anhedonia in patients with depression, and even the existing results of clinical trials are conflicting. In addition, there is no consensus on what brain regions should be targeted by tDCS during the treatment of anhedonia in patients with depression.

OBJECTIVE

This study aimed to evaluate the efficacy and safety of tDCS over the left dorsolateral prefrontal cortex (DLPFC) and right orbitofrontal cortex (OFC) in the improvement of anhedonia in patients with depression and finally identified suitable brain regions to be stimulated during treatment.

METHODS

This randomized, double-blind, sham-controlled clinical trial recruited 70 patients with anhedonia and depressive episodes. Patients were randomly assigned to three groups according to the stimulation site: right orbitofrontal cortex (OFC), left dorsolateral prefrontal cortex (DLPFC), and sham stimulation. Each group received twelve 20-min interventions (ten as primary treatment and two for consolidation). The primary outcome was a decrease in Snaith-Hamilton Pleasure Scale (SHAPS) scores after primary treatment. Evaluations were performed at baseline, post-treatment, and 8-week follow-up.

RESULTS

The depression mood of the three groups of patients at each time point was better than the baseline, but there was no significant difference in the efficacy between the groups (p>0.05). On the basis of the improvement of depression, this study found that tDCS of the DLPFC significantly improved anhedonia (p = 0.028) after primary treatment (2 weeks), and tDCS of the DLPFC and OFC significantly improved social functioning (p = 0.005) at 8-week follow-up.

LIMITATIONS

The sample size of this study was small, with only about 23/24 patients in each group completing the intervention assessments; due to the impact of the COVID-19 epidemic, data analysis was limited by the lack of patients during the follow-up period.

CONCLUSIONS

tDCS of the DLPFC significantly improves anhedonia in depressed patients and is thus a potential adjuvant therapy for anhedonia in these patients.

Comparing the performance of beamformer algorithms in estimating orientations of neural sources

The efficacy of transcranial electric stimulation (tES) to effectively modulate neuronal activity depends critically on the spatial orientation of the targeted neuronal population. Therefore, precise estimation of target orientation is of utmost importance. Different beamforming algorithms provide orientation estimates; however, a systematic analysis of their performance is still lacking. For fixed brain locations, EEG and MEG data from sources with randomized orientations were simulated. The orientation was then estimated (1) with an EEG and (2) with a combined EEG-MEG approach. Three commonly used beamformer algorithms were evaluated with respect to their abilities to estimate the correct orientation: Unit-Gain (UG), Unit-Noise-Gain (UNG), and Array-Gain (AG) beamformer. Performance depends on the signal-to-noise ratios for the modalities and on the chosen beamformer. Overall, the UNG and AG beamformers appear as the most reliable. With increasing noise, the UG estimate converges to a vector determined by the leadfield, thus leading to insufficient orientation estimates.

Improving depressive symptoms in patients with schizophrenia using bilateral bipolar-nonbalanced prefrontal tDCS: Results from a double-blind sham-controlled trial

BACKGROUND

Treating depressive symptoms in patients with schizophrenia is challenging. While transcranical Dicrect Current Stimulation (tDCS) improved other core symptoms of schizophrenia, conflicting results have been obtained on depressive symptoms. Thus, we aimed to expand current evidence on tDCS efficacy to improve depressive symptoms in patients with schizophrenia.

METHODS

A double-blind RCT was performed with patients randomized to 2 mA active-tDCS or sham-tDCS (15 daily sessions) with a bilateral bipolar-nonbalanced prefrontal placement (anode: left Dorsolateral prefrontal cortex; cathode: right orbitofrontal region). Clinical outcomes included variations of Calgary Depression Scale for Schizophrenia total score (CDSS) and of Depression-hopelessness and Guilty idea of reference-pathological guilt factors. Analysis of covariance was performed evaluating between-group changes over time. The presence/absence of probable clinically significant depression was determined when CDSS > 6.

RESULTS

As 50 outpatients were included (both groups, n = 25), significant improvements following active-tDCS were observed for CDSS total score (p = 0.001), Depression-hopelessness (p = 0.001) and Guilty idea of reference-pathological guilt (p = 0.03). Considering patients with CDSS>6 (n = 23), compared to sham, active-tDCS significantly improved CDSS total score (p < 0.001), Depression-hopelessness (p = 0.001) but Guilty idea of reference-pathological guilt only marginally improved (p = 0.051). Considering response rates of clinically significant depression, important reductions of CDSS score were observed (78 % of the sample scored ≤6; active-tDCS, n = 23; sham-tDCS, n = 16; p = 0.017). Early wakening item did not significantly change in any group.

LIMITATIONS

The study lacks a follow-up period and evaluation of tDCS effects on psychosocial functioning.

CONCLUSIONS

Bilateral bipolar-nonbalanced prefrontal tDCS is a successful protocol for the treatment of depressive symptoms in patients with schizophrenia.

tDCS reduces depression and state anxiety symptoms in older adults from the augmenting cognitive training in older adults study (ACT)

BACKGROUND

Pharmacological interventions for depression and anxiety in older adults often have significant side effects, presenting the need for more tolerable alternatives. Transcranial direct current stimulation (tDCS) is a promising non-pharmacological intervention for depression in clinical populations. However, its effects on depression and anxiety symptoms, particularly in older adults from the general public, are understudied.

OBJECTIVE

We conducted a secondary analysis of the Augmenting Cognitive Training in Older Adults (ACT) trial to assess tDCS efficacy in reducing psychological symptoms in older adults. We hypothesized that active stimulation would yield greater reductions in depression and state anxiety compared to sham post-intervention and at the one-year follow-up. We also explored tDCS effects in subgroups characterized by baseline symptom severity.

METHODS

A sample of 378 older adults recruited from the community completed a 12-week tDCS intervention with cognitive or education training. Electrodes were placed at F3/F4, and participants received active or sham tDCS during training sessions. We assessed the association between tDCS group and changes in depression, state anxiety, and trait anxiety from baseline to post-intervention and one-year controlling for covariates.

RESULTS

The active tDCS group demonstrated greater reductions in depression and state anxiety compared to sham post-intervention, particularly in individuals with mild depression and moderate/severe state anxiety at baseline. Furthermore, the active tDCS group with moderate/severe state anxiety maintained greater symptom reductions at one-year.

CONCLUSIONS

tDCS effectively reduced depression and state anxiety symptoms in a large sample of older adults. These findings highlight the importance of considering symptom severity when identifying those who may benefit most from this intervention.

Non-invasive brain stimulation for patients and healthy subjects: Current challenges and future perspectives

Non-invasive brain stimulation (NIBS) techniques have a rich historical background, yet their utilization has witnessed significant growth only recently. These techniques encompass transcranial electrical stimulation and transcranial magnetic stimulation, which were initially employed in neuroscience to explore the intricate relationship between the brain and behaviour. However, they are increasingly finding application in research contexts as a means to address various neurological, psychiatric, and neurodegenerative disorders. This article aims to fulfill two primary objectives. Firstly, it seeks to showcase the current state of the art in the clinical application of NIBS, highlighting how it can improve and complement existing treatments. Secondly, it provides a comprehensive overview of the utilization of NIBS in augmenting the brain function of healthy individuals, thereby enhancing their performance. Furthermore, the article delves into the points of convergence and divergence between these two techniques. It also addresses the existing challenges and future prospects associated with NIBS from ethical and research standpoints.

Adjunctive duration-doubled transcranial direct current stimulation for the treatment of depressive patients with suicidal ideation: study protocol for a double-blind, randomized, sham-controlled trial

BACKGROUND

The problem of suicide has become increasingly common in individuals with major depressive disorder (MDD). Transcranial direct current stimulation (tDCS) is an effective treatment for MDD with 2 milliamperes (mA) for at least 30 min per day for 2 weeks. This study aims to investigate the efficacy of daily duration-doubled tDCS as an adjunctive intervention for rapidly reducing suicidal ideation and improving depression in MDD patients.

METHODS

In this double-blind, randomized, sham-controlled study, 76 MDD patients with suicidal ideation are randomly assigned to either active (n=38) or sham (n=38) tDCS group. The anode and cathode are placed over the scalp areas corresponding to left and right dorsolateral prefrontal cortex (DLPFC), respectively, and each stimulation lasts for 60 min. The primary outcome is defined as change of Beck Scale for Suicide Ideation (BSI) after 5 and 10 sessions. The change of other clinical assessments, blood biomarkers related to suicidal ideation and depressive sumptoms are defined as secondary outcomes. Blood biomarkers related to suicidal ideation are collected at baseline and after 10 sessions.

DISCUSSION

This study suggests the adjunctive duration-doubled tDCS might be a novel method to rapidly reduce suicidal ideation and improve depressive symptom. The variation of biomarkers could be potential predictive models of suicide risk.

TRIAL REGISTRATION

The trial protocol is registered with ClinicalTrials.gov under protocol registration number NCT05555927. Registered on September 25, 2022.

Sex matters for the enhancement of cognitive training with transcranial direct current stimulation (tDCS)

BACKGROUND

Transcranial direct current stimulation (tDCS) can influence brain network activity and associated cognitive and behavioural functions. In addition to the extensive variety in stimulation parameters, numerous biological factors drive these effects, however these are yet poorly understood. Here, we investigate one of the major biological factors by focusing on sex-dependent effects of tDCS on a challenging cognitive control task (adaptive paced auditory serial addition task [PASAT]) in healthy humans.

METHODS

This sex-specific re-analysis was performed on data of 163 subjects who underwent a 2-week cognitive control training (6 sessions in total). Subjects received either verum (anodal/cathodal) or sham tDCS. Electrodes were placed over the left or right dorsolateral prefrontal cortex and the respective contralateral deltoid muscle. Cognitive control was measured as performance in the PASAT and was analysed in respect to stimulation conditions (sham, anodal, cathodal) and sex.

RESULTS

Regardless of stimulation condition, performance gains between the sexes were higher in females compared to males (p = 0.0038). Female's performance during anodal tDCS exceeded male's (p = 0.0070), yet no effects were found for cathodal or sham tDCS. Moreover, in females we found a superior effect for anodal tDCS over sham stimulation (fanodal: p = 0.0354; fcathodal: p = 0.6181), but no such effect in males (manodal: p = 0.6882; mcathodal: p = 0.4822).

CONCLUSIONS

This study highlights the relevance of biological sex for the effects of tDCS on cognitive training. Thus, an increased attention to biological sex is advisable in future brain stimulation research to highlight and in consequence better understand potentially underlying sex-specific mechanisms. Considering biological sex will further advance customisation and individualisation of tDCS interventions. Trial registration ClinicalTrials.gov, NCT04108663.

Home-administered transcranial direct current stimulation with asynchronous remote supervision in the treatment of depression: feasibility, tolerability, and clinical effectiveness

Introduction Background

Depression is an often chronic condition, characterized by wide-ranging physical, cognitive and psychosocial symptoms that can lead to disability, premature mortality or suicide. It affects 350 million people globally, yet up to 30% do not respond to traditional treatment, creating an urgent need for novel non-pharmacological treatments. This open-label naturalistic study assesses the practical feasibility, tolerability, and clinical effectiveness of home-administered transcranial direct current stimulation (tDCS) with asynchronous remote supervision, in the treatment of depression.

Method

Over the course of 3 weeks, 40 patients with depression received psychotherapy and half of this group also received daily bi-frontal tDCS stimulation of the dorsolateral prefrontal cortex. These patients received tDCS for 30 min per session with the anode placed over F3 and the cathode over F4, at an intensity of 2 mA for 21 consecutive days. We measured patients' level of depression symptoms at four time points using the Beck Depression Inventory, before treatment and at 1-week intervals throughout the treatment period. We monitored practical feasibility such as daily protocol compliance and tolerability including side effects, with the PlatoScience cloud-based remote supervision platform.

Results

Of the 20 patients in the tDCS group, 90% were able to comply with the protocol by not missing more than three of their assigned sessions, and none dropped out of the study. No serious adverse events were reported, with only 14 instances of mild to moderate side effects and two instances of scalp pain rated as severe, out of a total of 420 stimulation sessions. Patients in the tDCS group showed a significantly greater reduction in depression symptoms after 3 weeks of treatment, compared to the treatment as usual (TAU) group [t(57.2) = 2.268, p = 0.027]. The tDCS group also showed greater treatment response (50%) and depression remission rates (75%) compared to the TAU group (5 and 30%, respectively).

Discussion Conclusion

These findings provide a possible indication of the clinical effectiveness of home-administered tDCS for the treatment of depression, and its feasibility and tolerability in combination with asynchronous supervision.

tDCS efficacy and utility of anhedonia and rumination as clinical predictors of response to tDCS in major depressive disorder (MDD)

BACKGROUND

Anhedonia and rumination are mental disorders' transdiagnostic features but remain difficult to treat. Transcranial direct current stimulation (tDCS) is a proven treatment for depression, but its effects on anhedonia and rumination and whether anhedonia and rumination can be used as a predictive biomarker of treatment response is not well known. This study aimed to investigate the tDCS efficacy and identify the predictive role of anhedonia and rumination in response to tDCS in patients with MDD.

METHODS

182 patients received 10 tDCS sessions delivered at 2 mA to left (anode) dorsolateral prefrontal cortex (DLPFC). Hamilton Rating Scale for Depression (HRSD-17), Snaith-Hamilton Pleasure Scale (SHAPS), and the 10-item Ruminative Response Scale (RRS-10) was administered to patients with MDD before treatment, following it, and after two weeks of tDCS.

RESULTS

There was an overall significant improvement in anhedonia from pre- to post-treatment. Regression analyses revealed that responders had higher baseline anhedonia and rumination (reflective pondering) scores. We found that the reduction in HRSD scores after tDCS was significantly associated with anhedonia's baseline values while no relation was found between baseline rumination and tDCS treatment response.

CONCLUSION

These results provide new evidence that pronounced anhedonia may be a significant clinical predictor of response to tDCS. Patients with severe or low baseline rumination had an equal chance of achieving clinical response. Prospective tDCS studies are necessary to validate the predictive value of the derived model.

Transcranial direct current stimulation as an additional treatment to selective serotonin reuptake inhibitors in adults with major depressive disorder in Germany (DepressionDC): a triple-blind, randomised, sham-controlled, multicentre trial

BACKGROUND

Transcranial direct current stimulation (tDCS) has been proposed as a feasible treatment for major depressive disorder (MDD). However, meta-analytic evidence is heterogenous and data from multicentre trials are scarce. We aimed to assess the efficacy of tDCS versus sham stimulation as an additional treatment to a stable dose of selective serotonin reuptake inhibitors (SSRIs) in adults with MDD.

METHODS

The DepressionDC trial was triple-blind, randomised, and sham-controlled and conducted at eight hospitals in Germany. Patients being treated at a participating hospital aged 18-65 years were eligible if they had a diagnosis of MDD, a score of at least 15 on the Hamilton Depression Rating Scale (21-item version), no response to at least one antidepressant trial in their current depressive episode, and treatment with an SSRI at a stable dose for at least 4 weeks before inclusion; the SSRI was continued at the same dose during stimulation. Patients were allocated (1:1) by fixed-blocked randomisation to receive either 30 min of 2 mA bifrontal tDCS every weekday for 4 weeks, then two tDCS sessions per week for 2 weeks, or sham stimulation at the same intervals. Randomisation was stratified by site and baseline Montgomery-Åsberg Depression Rating Scale (MADRS) score (ie, <31 or ≥31). Participants, raters, and operators were masked to treatment assignment. The primary outcome was change on the MADRS at week 6, analysed in the intention-to-treat population. Safety was assessed in all patients who received at least one treatment session. The trial was registered with ClinicalTrials.gov (NCT02530164).

FINDINGS

Between Jan 19, 2016, and June 15, 2020, 3601 individuals were assessed for eligibility. 160 patients were included and randomly assigned to receive either active tDCS (n=83) or sham tDCS (n=77). Six patients withdrew consent and four patients were found to have been wrongly included, so data from 150 patients were analysed (89 [59%] were female and 61 [41%] were male). No intergroup difference was found in mean improvement on the MADRS at week 6 between the active tDCS group (n=77; -8·2, SD 7·2) and the sham tDCS group (n=73; -8·0, 9·3; difference 0·3 [95% CI -2·4 to 2·9]). Significantly more participants had one or more mild adverse events in the active tDCS group (50 [60%] of 83) than in the sham tDCS group (33 [43%] of 77; p=0·028).

INTERPRETATION

Active tDCS was not superior to sham stimulation during a 6-week period. Our trial does not support the efficacy of tDCS as an additional treatment to SSRIs in adults with MDD.

FUNDING

German Federal Ministry of Education and Research.

Personalized Repetitive Transcranial Magnetic Stimulation for Depression

Personalized treatments are gaining momentum across all fields of medicine. Precision medicine can be applied to neuromodulatory techniques, in which focused brain stimulation treatments such as repetitive transcranial magnetic stimulation (rTMS) modulate brain circuits and alleviate clinical symptoms. rTMS is well tolerated and clinically effective for treatment-resistant depression and other neuropsychiatric disorders. Despite its wide stimulation parameter space (location, angle, pattern, frequency, and intensity can be adjusted), rTMS is currently applied in a one-size-fits-all manner, potentially contributing to its suboptimal clinical response (∼50%). In this review, we examine components of rTMS that can be optimized to account for interindividual variability in neural function and anatomy. We discuss current treatment options for treatment-resistant depression, the neural mechanisms thought to underlie treatment, targeting strategies, stimulation parameter selection, and adaptive closed-loop treatment. We conclude that a better understanding of the wide and modifiable parameter space of rTMS will greatly improve the clinical outcome.

Time-course of the tDCS antidepressant effect: An individual participant data meta-analysis

INTRODUCTION

Prefrontal transcranial direct current stimulation (tDCS) shows promise as an effective treatment for depression. However, factors influencing treatment and the time-course of symptom improvements remain to be elucidated.

METHODS

Individual participant data was collected from ten randomised controlled trials of tDCS in depression. Depressive symptom scores were converted to a common scale, and a linear mixed effects individual growth curve model was fit to the data using k-fold cross-validation to prevent overfitting.

RESULTS

Data from 576 participants were analysed (tDCS: n = 311; sham: n = 265), of which 468 were unipolar and 108 had bipolar disorder. tDCS effect sizes reached a peak at approximately 6 weeks, and continued to diverge from sham up to 10 weeks. Significant predictors associated with worse response included higher baseline depression severity, treatment resistance, and those associated with better response included bipolar disorder and anxiety disorder.

CONCLUSIONS

Our findings suggest that longer treatment courses, lasting at least 6 weeks in duration, may be indicated. Further, our results show that tDCS is effective for depressive symptoms in bipolar disorder. Compared to unipolar depression, participants with bipolar disorder may require additional maintenance sessions to prevent rapid relapse.

Transcranial direct current stimulation for bipolar depression: systematic reviews of clinical evidence and biological underpinnings

Despite multiple available treatments for bipolar depression (BD), many patients face sub-optimal responses. Transcranial direct current stimulation (tDCS) has been advocated in the management of different conditions, including BD, especially in treatment-resistant cases. The optimal dose and timing of tDCS, the mutual influence with other concurrently administered interventions, long-term efficacy, overall safety, and biological underpinnings nonetheless deserve additional assessment. The present study appraised the existing clinical evidence about tDCS for bipolar depression, delving into the putative biological underpinnings with a special emphasis on cellular and molecular levels, with the ultimate goal of providing a translational perspective on the matter. Two separate systematic reviews across the PubMed database since inception up to August 8^th 2022 were performed, with fourteen clinical and nineteen neurobiological eligible studies. The included clinical studies encompass 207 bipolar depression patients overall and consistently document the efficacy of tDCS, with a reduction in depression scores after treatment ranging from 18% to 92%. The RCT with the largest sample clearly showed a significant superiority of active stimulation over sham. Mild-to-moderate and transient adverse effects are attributed to tDCS across these studies. The review of neurobiological literature indicates that several molecular mechanisms may account for the antidepressant effect of tDCS in BD patients, including the action on calcium homeostasis in glial cells, the enhancement of LTP, the regulation of neurotrophic factors and inflammatory mediators, and the modulation of the expression of plasticity-related genes. To the best of our knowledge, this is the first study on the matter to concurrently provide a synthesis of the clinical evidence and an in-depth appraisal of the putative biological underpinnings, providing consistent support for the efficacy, safety, and tolerability of tDCS.

Brain stimulation treatment for bipolar disorder

AIMS

Bipolar disorders are clinically complex, chronic and recurrent disorders. Few treatment options are effective across hypomanic, manic, depressive and mixed states and as continuation or maintenance treatment after initial symptom remission. The aim of this review was to provide an up-to-date overview of research on the efficacy, tolerability and cognitive effects of electroconvulsive therapy (ECT), transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), magnetic seizure therapy (MST), deep brain stimulation (DBS) and vagus nerve stimulation (VNS).

METHODS

References included in this review were identified through multiple searches of the Embase, PubMed/MEDLINE and APA PsycINFO electronic databases for articles published from inception until February 2022. Published reviews, meta-analyses, randomised controlled trials and recent studies were prioritised to provide a comprehensive and up-to-date overview of research on brain stimulation in patients with bipolar disorders.

RESULTS

The evidence base for brain stimulation as an add-on or alternative to pharmacological and psychological treatments in patients with bipolar disorders is limited but rapidly expanding. Brain stimulation treatments represent an opportunity to treat all bipolar disorder states, including cognitive dysfunction during euthymic periods.

CONCLUSION

Whilst findings to date have been encouraging, larger randomised controlled trials with long-term follow-up are needed to clarify important questions regarding treatment efficacy and tolerability, the frequency of treatment-emergent affective switches and effects on cognitive function.

Novel and emerging treatments for major depression

Depression is common, costly, debilitating, and associated with increased risk of suicide. It is one of the leading global public health problems. Although existing available pharmacological treatments can be effective, their onset of action can take up to 6 weeks, side-effects are common, and recovery can require treatment with multiple different agents. Although psychosocial interventions might also be recommended, more effective treatments than those currently available are needed for people with moderate or severe depression. In the past 10 years, treatment trials have developed and tested many new targeted interventions. In this Review, we assess novel and emerging biological treatments for major depressive disorder, evaluate their putative brain and body mechanisms, and highlight how close each might be to clinical use.

How does IL-6 change after combined treatment in MDD patients? A systematic review

A growing amount of research suggests that inflammatory responses have a crucial role in the complex pathophysiology of Major Depressive Disorder (MDD), a disabling medical condition. The present review has two primary goals. Firstly, to highlight and summarize results from studies that investigated the changes of IL-6 in MDD patients before and after combined treatment. The second aim is to enlighten the need for further research on the difference in the concentration of the pro-inflammatory cytokines between MDD and Treatment-Resistant MDD. The protocol of this study was written using PRISMA, and it is registered at PROSPERO (identification: CRD42021289233). We searched the following bibliographic databases to identify potentially eligible articles without any time limit until September 2021: Pubmed, Web of Science, Scopus, PsycINFO. As they met the eligibility criteria, 14 articles were included in this systematic review. The selected studies assessed twelve different elements as an adjunction to the standard pharmacotherapy (ECT, Ketamine, CBT, NCT, Ketoprofene, Lithium, Celecoxib, Metformin tDCS, Pentoxifylline, ethyl-EPA, Zinc). Significant results were found in the studies that analyzed the impact of combined treatment with the adjunction of the following elements: ECT, Ketamine, CBT, NCT, Celecoxib, Metformin, and Pentoxifylline. Overall, this systematic review identifies several potentially beneficial combined treatments for MDD patients. Further evidence is needed to confirm the efficacy of reducing IL-6 levels in patients with Treatment-Resistant MDD.

Is transcranial direct current stimulation beneficial for treating pain, depression, and anxiety symptoms in patients with chronic pain? A systematic review and meta-analysis

Background

Chronic pain is often accompanied by emotional dysfunction. Transcranial direct current stimulation (tDCS) has been used for reducing pain, depressive and anxiety symptoms in chronic pain patients, but its therapeutic effect remains unknown.

Objectives

To ascertain the treatment effect of tDCS on pain, depression, and anxiety symptoms of patients suffering from chronic pain, and potential factors that modulate the effectiveness of tDCS.

Methods

Literature search was performed on PubMed, Embase, Web of Science, and Cochrane Library from inception to July 2022. Randomized controlled trials that reported the effects of tDCS on pain and depression and anxiety symptoms in patients with chronic pain were included.

Results

Twenty-two studies were included in this review. Overall pooled results indicated that the use of tDCS can effectively alleviate short-term pain intensity [standard mean difference (SMD): -0.43, 95% confidence interval (CI): -0.75 to -0.12, P = 0.007] and depressive symptoms (SMD: -0.31, 95% CI, -0.47 to -0.14, P < 0.001), middle-term depressive symptoms (SMD: -0.35, 95% CI: -0.58 to -0.11, P = 0.004), long-term depressive symptoms (ES: -0.38, 95% CI: -0.64 to -0.13, P = 0.003) and anxiety symptoms (SMD: -0.26, 95% CI: -0.51 to -0.02, P = 0.03) compared with the control group.

Conclusion

tDCS may be an effective short-term treatment for the improvement of pain intensity and concomitant depression and anxiety symptoms in chronic pain patients. Stimulation site, stimulation frequency, and type of chronic pain were significant influence factors for the therapeutic effect of tDCS.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=297693, identifier: CRD42022297693.

Can brain stimulation enhance cognition in clinical populations? A critical review

Many psychiatric and neurological conditions are associated with cognitive impairment for which there are very limited treatment options. Brain stimulation methodologies show promise as novel therapeutics and have cognitive effects. Electroconvulsive therapy (ECT), known more for its related transient adverse cognitive effects, can produce significant cognitive improvement in the weeks following acute treatment. Transcranial magnetic stimulation (TMS) is increasingly used as a treatment for major depression and has acute cognitive effects. Emerging research from controlled studies suggests that repeated TMS treatments may additionally have cognitive benefit. ECT and TMS treatment cause neurotrophic changes, although whether these are associated with cognitive effects remains unclear. Transcranial electrical stimulation methods including transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS) are in development as novel treatments for multiple psychiatric conditions. These treatments may also produce cognitive enhancement particularly when stimulation occurs concurrently with a cognitive task. This review summarizes the current clinical evidence for these brain stimulation treatments as therapeutics for enhancing cognition. Acute, or short-lasting, effects as well as longer-term effects from repeated treatments are reviewed, together with potential putative neural mechanisms. Areas of future research are highlighted to assist with optimization of these approaches for enhancing cognition.

A pilot randomized clinical trial of tDCS for increasing exercise engagement in individuals with elevated depressive symptoms: Rationale, design, and baseline characteristics

Regular exercise protects against overweight/obesity as well as numerous chronic diseases. Yet, less than half of Americans exercise sufficiently. Elevated levels of depressive symptoms have been identified as an important correlate of physical inactivity as well as poor adherence to exercise programs. Individuals with depression are less sensitive to rewards and demonstrate an attentional bias toward negative stimuli. These, and other features of depression, may place them at increased risk for effectively managing the affective experience of exercise. Lower baseline levels of activation of the left (vs right) frontal cortex, an area implicated in affect regulation, have also been found in depression, potentially pointing to this region as a potential target for intervening on affect regulation during exercise. Transcranial direct current stimulation (tDCS) has shown promise in impacting a variety of cognitive and affective processes in a large number of individuals, including people with depression. Some findings have suggested that tDCS targeting the left dorsolateral prefrontal cortex (DLPFC), specifically, may improve emotion regulation. Transcranial direct current stimulation could theoretically be a novel and potentially promising approach to improving the affective experience of exercise, thereby increasing exercise adherence among individuals with depressive symptoms. Here we present the rationale, design, and baseline characteristics of a pilot randomized controlled trial of tDCS versus sham delivered 3x/week for 8 weeks in the context of supervised aerobic exercise (AE) program among 51 low-active individuals with elevated depressive symptoms (86.3% female; mean age = 49.5). Follow-up assessments were conducted at end of treatment, and three and six months after enrollment to examine changes in levels of objectively-measured moderate-to-vigorous physical activity (MVPA). If effective, this approach could have high public health impact on preventing obesity and chronic diseases among these at-risk individuals.

A Single Session of Bifrontal tDCS Can Improve Facial Emotion Recognition in Major Depressive Disorder: An Exploratory Pilot Study

Emotional processing deficits are key features in major depressive disorder (MDD). Neuroimaging studies indicate that the dorsolateral prefrontal cortex (DLPFC) plays a pivotal role in both depressive symptoms and emotional processing. Recently, transcranial Direct Current Stimulations (tDCS) applied over the DLPFCs have held the promise to alleviate the symptoms in patients with MDD, but the effect on emotional processing in the patients is unclear. Here, we investigated the effect of a single session of tDCS over the DLPFCs on the emotional processing in patients with treatment-resistant MDD. In a randomized sham-controlled study, 35 patients received a single 30 min session of either active (2 mA, n = 18) or sham tDCS (n = 17). The anode was placed over the left and the cathode over the right DLPFC. Emotional processing accuracy was measured by a facial emotion recognition (FER) task. We observed an overall improvement in FER performance after the active tDCS, but not the sham tDCS. These exploratory results suggest that a single session of tDCS over the DLPFCs may improve FER in MDD, a crucial function of social cognition. Further studies are needed to investigate whether this acute improvement of FER in response to a single tDCS session could translate into clinical benefits or predict remission following repeated sessions of stimulation.

Boosting psychological change: Combining non-invasive brain stimulation with psychotherapy

Mental health disorders and substance use disorders are a leading cause of morbidity and mortality worldwide, and one of the most important challenges for public health systems. While evidence-based psychotherapy is generally pursued to address mental health challenges, psychological change is often hampered by non-adherence to treatments, relapses, and practical barriers (e.g., time, cost). In recent decades, Non-invasive brain stimulation (NIBS) techniques have emerged as promising tools to directly target dysfunctional neural circuitry and promote long-lasting plastic changes. While the therapeutic efficacy of NIBS protocols for mental illnesses has been established, neuromodulatory interventions might also be employed to support the processes activated by psychotherapy. Indeed, combining psychotherapy with NIBS might help tailor the treatment to the patient's unique characteristics and therapeutic goal, and would allow more direct control of the neuronal changes induced by therapy. Herein, we overview emerging evidence on the use of NIBS to enhance the psychotherapeutic effect, while highlighting the next steps in advancing clinical and research methods toward personalized intervention approaches.

Variation of cerebrospinal fluid in specific regions regulates focality in transcranial direct current stimulation

Background

Conventionally, transcranial direct current stimulation (tDCS) aims to focalize the current reaching the target region-of-interest (ROI). The focality can be quantified by the dose-target-determination-index (DTDI). Despite having a uniform tDCS setup, some individuals receive focal stimulation (high DTDI) while others show reduced focality ("non-focal"). The volume of cerebrospinal fluid (CSF), gray matter (GM), and white matter (WM) underlying each ROI govern the tDCS current distribution inside the brain, thereby regulating focality.

Aim

To determine the regional volume parameters that differentiate the focal and non-focal groups.

Methods

T1-weighted images of the brain from 300 age-sex matched adults were divided into three equal groups- (a) Young (20 ≤ × < 40 years), (b) Middle (40 ≤ × < 60 years), and (c) Older (60 ≤ × < 80 years). For each group, inter and intra-hemispheric montages with electrodes at (1) F3 and right supraorbital region (F3-RSO), and (2) CP5 and Cz (CP5-Cz) were simulated, targeting the left- Dorsolateral Prefrontal Cortex (DLPFC) and -Inferior Parietal Lobule (IPL), respectively. Both montages were simulated for two current doses (1 and 2 mA). For each individual head simulated for a tDCS configuration (montage and dose), the current density at each region-of-interest (ROI) and their DTDI were calculated. The individuals were categorized into two groups- (1) Focal (DTDI ≥ 0.75), and (2) Non-focal (DTDI < 0.75). The regional volume of CSF, GM, and WM of all the ROIs was determined. For each tDCS configuration and ROI, three 3-way analysis of variance was performed considering- (i) GM, (ii) WM, and (iii) CSF as the dependent variable (DV). The age group, sex, and focality group were the between-subject factors. For a given ROI, if any of the 3 DV's showed a significant main effect or interaction involving the focality group, then that ROI was classified as a "focal ROI."

Results

Regional CSF was the principal determinant of focality. For interhemispheric F3-RSO montage, interaction effect (p < 0.05) of age and focality was observed at Left Caudate Nucleus, with the focal group exhibiting higher CSF volume. The CSF volume of focal ROI correlated positively (r ∼ 0.16, p < 0.05) with the current density at the target ROI (DLPFC). For intrahemispheric CP5-Cz montage, a significant (p < 0.05) main effect was observed at the left pre- and post-central gyrus, with the focal group showing lower CSF volume. The CSF volume correlated negatively (r ∼ -0.16, p < 0.05) with current density at left IPL. The results were consistent for both current doses.

Conclusion

The CSF channels the flow of tDCS current between electrodes with focal ROIs acting like reservoirs of current. The position of focal ROI in the channel determines the stimulation intensity at the target ROI. For focal stimulation in interhemispheric F3-RSO, the proximity of focal ROI reserves the current density at the target ROI (DLPFC). In contrast, for intrahemispheric montage (CP5-Cz), the far-end location of focal ROI reduces the current density at the target (IPL).

Adjunctive home-based transcranial direct current stimulation treatment for major depression with real-time remote supervision: An open-label, single-arm feasibility study with long term outcomes

Current treatments for major depressive disorder (MDD) have limited effectiveness and acceptability. Transcranial direct current stimulation (tDCS) is a novel non-invasive brain stimulation method that has demonstrated treatment efficacy in MDD. tDCS requires daily sessions, however clinical trials have been conducted in research centers requiring repeated visits. As tDCS is portable and safe, it could be provided at home. We developed a home-based protocol with real-time supervision, and we examined the clinical outcomes, acceptability and feasibility. Participants were 26 MDD (19 women), mean age 40.9 ± 14.2 years, in current depressive episode of moderate to severe severity (mean 17-item Hamilton Rating Scale for Depression (HAMD) score 19.12 ± 2.12). tDCS was provided in a bilateral frontal montage, F3 anode, F4 cathode, 2 mA, each session 30 min, in a 6-week trial, for a total 21 sessions. Participants maintained their current treatment (antidepressant medication, psychotherapy, or were enrolled in online CBT). Two tDCS device brands were used, and a research team member was present in person or by real-time video call at each session. 92.3% MDD participants (n = 24) completed the 6-week treatment. Attrition rate was 7.7%. There was a significant improvement in depressive symptoms following treatment (mean HAMD 5.33 ± 2.33), which was maintained at 6 months (mean HAMD 5.43 ± 2.73). Acceptability was endorsed as "very acceptable" or "quite acceptable" by all participants. Due to the open-label feasibility design, efficacy findings are preliminary. In summary, home-based tDCS with real-time supervision was associated with significant clinical improvements and high acceptability which were maintained in the long term.

Efficiency of Transcranial Direct Current Stimulation (tDCS) in Anorexia Nervosa Treatment- Case Report

Introduction: Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation with considerable potential as a treatment for many CNS disorders. Individuals suffering from eating disorders have elevated rates of lifetime depression, anxiety and obsessive-compulsive disorder, also affecting specific brain regions. More studies assess the effect of brain modulation in anorexia nervosa (AN). This study aimed to evaluate the effect, tolerability and safety of tDCS stimulation in the patient with an AN diagnosis.

Material and method: The therapy was implemented in an 18-year-old female hospitalized at the I Department of Psychiatry, Psychotherapy and Early Intervention Medical University of Lublin. The simulation was performed twice daily for 25 minutes for two weeks, 20 sessions. To assess a. anthropometric measures, bioelectrical impedance analysis was conducted; b. biological factors fasting venous blood was drawn; c. psychological aspects: Eating Attitudes Test, Rosenberg self-esteem scale, Beck Depression Inventory, Eating Disorder Examination Questionnaire, Body Esteem Scale, Perceived Stress Scale were used.

Results: The patient responded well to stimulation - apart from a mild headache. After tDCS sessions, improvement in anthropometric measurements, mood, and body self-esteem was observed. No severe changes in blood parameters were observed after the intervention.

Conclusions: Described study case offer preliminary support for achieving meaningful clinical outcomes using transcranial stimulation. However, future clinical studies compared to the placebo group are necessary for proposing a new type of AN therapy.

Non-invasive stimulation with Temporal Interference: Optimization of the electric field deep in the brain with the use of a genetic algorithm

OBJECTIVE

Since the introduction of transcranial temporal interference stimulation (tTIS), there has been an ever-growing interest in this novel method, as it theoretically allows non-invasive stimulation of deep brain target regions. To date, attempts have been made to optimize the electrode montages and injected current to achieve personalized area targeting using two electrode pairs. Most of these methods use exhaustive search to find the best match, but faster and, at the same time, reliable solutions are required. In this study, the electrode combinations as well as the injected current for a two-electrode pair stimulation were optimized using a genetic algorithm, considering the right hippocampus as the region of interest (ROI).

METHODS

Simulations were performed on head models from the Population Head Model (PHM) repository. First, each model was fitted with an electrode array based on the 10-10 international EEG electrode placement system. Following electrode placement, the models were meshed and solved for all single-pair electrode combinations, using an electrode on the left mastoid as a reference (ground). At the optimization stage, different electrode pairs and injection currents were tested using a genetic algorithm to obtain the optimal combination for each model, by setting three different maximum electric field thresholds (0.2, 0.5, and 0.8 V/m) in the ROI. The combinations below the set threshold were given a high penalty.

RESULTS

Greater focality was achieved with our optimization, specifically in the ROI, with a significant decrease in the surrounding electric field intensity. In the non-optimized case, the mean brain volumes stimulated above 0.2 V/m were 99.9% in the ROI, and 76.4% in the rest of the gray matter. In contrast, the stimulated mean volumes were 91.4% and 29.6%, respectively, for the best optimization case with a threshold of 0.8 V/m. Additionally, the maximum electric field intensity inside the ROI was consistently higher than that outside of the ROI for all optimized cases.

SIGNIFICANCE

Given that the accomplishment of a globally optimal solution requires a brute-force approach, the use of a genetic algorithm can significantly decrease the optimization time, while achieving personalized deep brain stimulation. The results of this work can be used to facilitate further studies that are more clinically oriented; thus, enabling faster and at the same time accurate treatment planning for the stimulation sessions.

Disentangling cognitive inflexibility in major depressive disorder: A transcranial direct current stimulation study

BACKGROUND

Cognitive dysfunction is a persistent residual symptom in major depressive disorders (MDDs) that hinders social and occupational recovery. Cognitive inflexibility is a typical cognitive dysfunction in MDD and refers to difficulty in switching tasks, which requires two subcomponents: forgetting an old task and adapting to a new one. Here, we aimed to disentangle the subcomponents of cognitive inflexibility in MDD and investigate whether they can be improved by transcranial direct current stimulation (tDCS) on the prefrontal cortex.

METHODS

The current study included 20 patients with MDD (seven females) and 22 age-matched healthy controls (HCs) (seven females). The participants received anodal tDCS on either the dorsomedial prefrontal cortex (DMPFC) or dorsolateral prefrontal cortex (DLPFC) in a crossover design. Before and after the application of tDCS, the participants performed a modified Wisconsin Card Sorting Test, in which the task-switching rules were explicitly described and proactive interference from a previous task rule was occasionally released.

RESULTS

We found that the behavioral cost of a task switch was increased in patients with MDD, but that of proactive interference was comparable between patients with MDD and HCs. The response time for anodal DMPFC tDCS was decreased compared with that for anodal tDCS on the DLPFC in MDD.

CONCLUSIONS

These findings suggest that cognitive inflexibility in MDD is primarily explained by the difficulty to adapt to a new task and environment, and that tDCS on the DMPFC improves behavioral performance during cognitively demanding tasks that require conflict resolution.

What role for cognitive remediation in the treatment of depressive symptoms? A superiority and noninferiority meta-analysis for clinicians

BACKGROUND

Cognitive remediation (CR) is a promising technique in the treatment of the cognitive dimension of depression. The present study evaluated the potential of CR in treating depressive symptoms and provides practical information about its usefulness in clinical settings.

METHODS

We performed two meta-analyses of published randomized (and nonrandomized) clinical trials, comparing CR to control conditions in subjects with current depressive symptomatology. The superiority meta-analysis aimed to determine the superiority of CR when compared with placebo/waiting list interventions and its efficacy when used as an augmentation therapy. The noninferiority meta-analysis determined whether CR had noninferior efficacy compared with standard antidepressant interventions.

RESULTS

CR was found to significantly improve depressive symptomatology in the superiority meta-analysis (CR: n = 466, control n = 478). Moreover, CR seemed to be noninferior to standard antidepressant interventions (CR: n = 230, control n = 235). CR was more effective when addressing hot (vs. cold) cognition, when involving younger patients (i.e., <30 years), and in the case of mild-moderate (vs. severe) depression.

CONCLUSIONS

CR should be considered an augmentation treatment to improve treatment outcomes in depressed subjects, especially among young individuals. Interventions addressing hot cognition seem to be the most promising.

A Clinical Case Series of Acute and Maintenance Home Administered Transcranial Direct Current Stimulation in Treatment-Resistant Depression

OBJECTIVES

Transcranial direct current stimulation (tDCS) is a noninvasive neurostimulation technique being translated clinically for the treatment of depression. There is limited research documenting the longer-term effectiveness and safety of tDCS treatment. This case series is the first report of remotely supervised, home-administered tDCS (HA-tDCS) for depression in a clinical setting.

METHODS

We report clinical, cognitive, and safety outcomes from 16 depressed patients who received acute and/or maintenance HA-tDCS. We retrospectively examined clinical data from up to 2.5 years of treatment. Descriptive statistics are reported to document patient outcomes.

RESULTS

Twelve patients received acute treatment for a current depressive episode and 4 commenced tDCS maintenance therapy after responding to ECT or repetitive transcranial magnetic stimulation (rTMS). The cohort was highly treatment-resistant wherein 15 of 16 patients failed 3 trials or more of antidepressant medication in the current episode, and 6 patients failed to gain significant benefit from prior ECT or rTMS. Five of 12 patients responded to acute tDCS within 6 weeks, and 9 patients who received tDCS for more than 12 weeks maintained improvements over several months. Cognitive tests showed no evidence of impairments in cognitive outcomes after up to 2 years of treatment. Two patients were withdrawn from treatment because of blurred vision or exacerbation of tinnitus. Transcranial direct current stimulation was otherwise safe and well tolerated.

CONCLUSIONS

Transcranial direct current stimulation given for at least 6 weeks may be of clinical benefit even in treatment-resistant depression. Results provide support for long-term effectiveness, safety, and feasibility of remotely supervised HA-tDCS and suggest a role for maintenance tDCS after acute treatment with tDCS, rTMS, or ECT.

Differences in electric field strength between clinical and non-clinical populations induced by prefrontal tDCS: A cross-diagnostic, individual MRI-based modeling study

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MDD and SCZ showed lower prefrontal tDCS-induced e-field strengths compared to HC.

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Average e-field strengths did not significantly differ between MDD and SCZ patients.

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Inter-individual variability of e-field intensities and distribution was prominent.

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Inter-rater variability emphasizes the importance of standardized positioning.

Introduction

Prefrontal cortex (PFC) regions are promising targets for therapeutic applications of non-invasive brain stimulation, e.g. transcranial direct current stimulation (tDCS), which has been proposed as a novel intervention for major depressive disorder (MDD) and negative symptoms of schizophrenia (SCZ). However, the effects of tDCS vary inter-individually, and dose–response relationships have not been established. Stimulation parameters are often tested in healthy subjects and transferred to clinical populations. The current study investigates the variability of individual MRI-based electric fields (e-fields) of standard bifrontal tDCS across individual subjects and diagnoses.

Method

The study included 74 subjects, i.e. 25 patients with MDD, 24 patients with SCZ, and 25 healthy controls (HC). Individual e-fields of a common tDCS protocol (i.e. 2 mA stimulation intensity, bifrontal anode-F3/cathode-F4 montage) were modeled by two investigators using SimNIBS (2.0.1) based on structural MRI scans.

Result

On a whole-brain level, the average e-field strength was significantly reduced in MDD and SCZ compared to HC, but MDD and SCZ did not differ significantly. Regions of interest (ROI) analysis for PFC subregions showed reduced e-fields in Sallet areas 8B and 9 for MDD and SCZ compared to HC, whereas there was again no difference between MDD and SCZ. Within groups, we generally observed high inter-individual variability of e-field intensities at a higher percentile of voxels.

Conclusion

MRI-based e-field modeling revealed significant differences in e-field strengths between clinical and non-clinical populations in addition to a general inter-individual variability. These findings support the notion that dose–response relationships for tDCS cannot be simply transferred from healthy to clinical cohorts and need to be individually established for clinical groups. In this respect, MRI-based e-field modeling may serve as a proxy for individualized dosing.

How a transdiagnostic approach can improve the treatment of emotional disorders: Insights from clinical psychology and neuroimaging

Multiple psychological treatments for emotional disorders have been developed and implemented, improving the quality of life of individuals. Nevertheless, relapse and poor response to psychotherapy are common. This article argues that a greater understanding of both the psychological and neurobiological mechanisms of change in psychotherapy is essential to improve treatment for emotional disorders. It aims to demonstrate how an understanding of these mechanisms provides a basis for (i) reconceptualizing some mental disorders, (ii) refining and establishing the evidence for existing therapeutic techniques and (iii) designing new techniques that precisely target the processes that maintain these disorders. Possible future directions for researchers and practitioners working at the intersection of neuropsychology and clinical psychology are discussed.

Dissociating the role of dACC and dlPFC for emotion appraisal and mood regulation using cathodal tDCS

Several neuroimaging studies have shown that a distributed network of brain regions is involved in our ability to appraise the emotions we experience in daily life. In particular, scholars suggested that the dorsal anterior cingulate cortex (dACC) may play a role in the appraisal of emotional stimuli together with subcortical regions, especially when stimuli are negatively valenced, and the dorsolateral prefrontal cortex (dlPFC) may play a role in regulating emotions. However, proofs of the causal role of these regions are lacking. In the present study, we aim at testing this model by stimulating both the dACC and the left dlPFC via cathodal tDCS. Twenty-four participants were asked to attend and rate the arousal and valence of negative and neutral emotional stimuli (pictures and words) in three different experimental sessions: cathodal stimulation of dACC, left dlPFC, or sham. In addition to the experimental task, the baseline affective state was measured before and after the stimulation to further assess the effect of stimulation over the baseline affective state after the experimental session. Results showed that cathodal stimulation of dACC, but not the left dlPFC, was associated with reduced arousal ratings of emotional stimuli, both compared with the sham condition. Moreover, cathodal stimulation of left dlPFC decreased participant's positive affective state after the session. These findings suggest for the first time, a dissociation between the dACC and dlPFC, with the former more involved in emotion appraisal, and the latter more involved in mood modulation.

Safety and Feasibility of Tele-Supervised Home-Based Transcranial Direct Current Stimulation for Major Depressive Disorder

Major depressive disorder (MDD) is a worldwide cause of disability in older age, especially during the covid pandemic. Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique that has shown encouraging efficacy for treatment of depression. Here, we investigate the feasibility of an innovative protocol where tDCS is administered within the homes of older adults with MDD (patient participants) with the help of a study companion (i.e. caregiver). We further analyze the feasibility of a remotely-hosted training program that provides the knowledge and skills to administer tDCS at home, without requiring them to visit the lab. We also employed a newly developed multi-channel tDCS system with real-time monitoring designed to guarantee the safety and efficacy of home-based tDCS. Patient participants underwent a total of 37 home-based tDCS sessions distributed over 12 weeks. The protocol consisted of three phases each lasting four weeks: an acute phase, containing 28 home-based tDCS sessions, a taper phase containing nine home-based tDCS sessions, and a follow up phase, with no stimulation sessions. We found that the home-based, remotely-supervised, study companion administered, multi-channel tDCS protocol for older adults with MDD was feasible and safe. Further, the study introduces a novel training program for remote instruction of study companions in the administration of tDCS. Future research is required to determine the translatability of these findings to a larger sample.

Clinical Trial Registration:https://clinicaltrials.gov/ct2/show/NCT04799405?term=NCT04799405&amp;draw=2&amp;rank=1, identifier NCT04799405.

Ten Sessions of 30 Min tDCS over 5 Days to Achieve Remission in Depression: A Randomized Pilot Study

Although transcranial Direct Current stimulation (tDCS) shows promise in the treatment of major depressive episodes, the optimal parameters and population to target remain unclear. We investigated the clinical interest of a 10 session tDCS regimen in patients with mild to severe treatment-resistant depression, in a pilot double-blind, randomized sham-controlled trial. tDCS was delivered over 5 consecutive days (two 30 min sessions per day separated by at least 2 h, 2 mA). The anode and cathode were placed over the left and the right dorsolateral prefrontal cortex, respectively. One month after tDCS, we observed significantly fewer patients who achieved remission (MADRS₁₀ < 10) in the sham group (0 out of 18 patients) than in the active group (5 out of 21 patients; p = 0.05). However, no significant difference was observed between the groups regarding the mean scores of severity changes throughout the study period. Bifrontal add-on tDCS delivered twice per day over 5 days, in combination with antidepressant medication, can be a safe and suitable approach to achieve remission in patients with mild to severe treatment-resistant major depressive disorder. However, in regards to the pilot nature and limitations of the present study, further studies are needed before any frank conclusions can be made regarding the use of tDCS with the proposed parameters in clinical settings.

Transcranial Electrical Stimulation for Psychiatric Disorders in Adults: A Primer

Transcranial electrical stimulation (tES) comprises noninvasive neuromodulation techniques that deliver low-amplitude electrical currents to targeted brain regions with the goal of modifying neural activities. Expanding evidence from the past decade, specifically using transcranial direct current simulation and transcranial alternating current stimulation, presents promising applications of tES as a treatment for psychiatric disorders. In this review, the authors discuss the basic technical aspects and mechanisms of action of tES in the context of clinical research and practice and review available evidence for its clinical use, efficacy, and safety. They also review recent advancements in use of tES for the treatment of depressive disorders, schizophrenia, substance use disorders, and obsessive-compulsive disorder. Findings largely support growing evidence for the safety and efficacy of tES in the treatment of patients with resistance to existing treatment options, particularly demonstrating promising treatment outcomes for depressive disorders. Future directions of tES research for optimal application in clinical settings are discussed, including the growing home-based, patient-friendly methods and the potential pairing with existing pharmacological or psychotherapeutic treatments for enhanced outcomes. Finally, neuroimaging advancements may provide more specific mapping of brain networks, aiming at more precise tES therapeutic targeting in the treatment of psychiatric disorders.

Altered Visual Cortical Excitability Is Associated With Psychopathological Symptoms in Major Depressive Disorder

Previous studies suggest that in people with major depressive disorder (MDD), there exists a perturbation of the normal balance between the excitatory and inhibitory neurotransmitter systems in the visual cortex, indicating the possibility of altered visual cortical excitability. However, investigations into the neural activities of the visual cortex in MDD patients yielded inconsistent findings. The present study aimed to evaluate the visual cortical excitability utilizing a paired-pulse stimulation paradigm in patients with MDD and to access the paired-pulse behavior of recording visual evoked potentials (VEPs) as a marker of MDD. We analyzed the amplitudes of VEPs and paired-pulse suppression (PPS) at four different stimulus onset asynchronies (SOAs) spanning 93 ms to 133 ms. Further, the relationship between PPS and the symptom severity of depression was investigated using Spearman's correlation. We found that, whereas the first VEP amplitude remained unchanged, the second VEP amplitude was significantly higher in the MDD group compared to the healthy controls. As a result, the amplitude ratio (second VEP amplitude/first VEP amplitude) increased, indicating reduced PPS and thus increased excitability in the visual cortex. Moreover, we found the amplitude ratios had a significantly positive correlation with the symptom severity of depression in MDD, indicating a clinically useful biomarker for MDD. Our findings provide new insights into the changes in the excitation-inhibition balance of visual cortex in MDD, which could pave the way for specific clinical interventions.