Research trends and knowledge mapping of transcranial direct current stimulation in depression: a bibliometric study based on web of science, Scopus, and PubMed (2000-2025)

BackgroundDepressive disorders are clinically heterogeneous and mechanistically complex psychiatric conditions. Transcranial direct current stimulation (tDCS), a key non-invasive neuromodulation technique, has expanded rapidly in both therapeutic application and mechanistic research. However, the field is marked by rapid publication growth, thematic diversity, and variability in evidence quality. A systematic quantitative synthesis is therefore needed to map the research landscape, identify hotspots, and inform future directions.MethodsA systematic search was conducted for English-language publications in the Web of Science Core Collection (WoSCC), Scopus, and PubMed using the terms (“Transcranial direct current stimulation” OR “tDCS”) AND (“depression” OR “major depressive disorder” OR “depressive disorder” OR “MDD”). Only articles and reviews were included. Records from 2026 and non-research publications, including conference abstracts, editorials, letters, news items, and errata, were excluded. Deduplication was performed using DOI-based matching followed by title-assisted matching. Bibliometrix (R), VOSviewer, and CiteSpace were used to analyze publication trends, contributions by countries/regions, institutions, authors, and journals, collaboration networks, keyword co-occurrence, thematic clustering, and burst terms. Citation analysis was based on WoSCC data only.ResultsResearch on tDCS for depression showed sustained growth, with marked acceleration after 2020 and a peak in 2024. The United States, Germany, and Brazil occupied central positions in both productivity and international collaboration, with the United States ranking first in publication volume. Major research hubs included the Universidade de São Paulo, the University of Toronto, and Harvard University, while Brain Stimulation, Journal of Affective Disorders, and Frontiers in Psychiatry were the leading publication venues. Highly cited studies mainly focused on neurophysiological mechanisms, pivotal randomized controlled trials, and evidence-based guidelines. Keyword analyses indicated a shift from early attention to cortical excitability, safety, and short-term efficacy toward a more integrated framework involving prefrontal-targeted stimulation, cognitive function, functional connectivity, treatment outcomes, and cross-disorder applications.ConclusiontDCS research in depression is entering a multidimensional and interdisciplinary phase, with increasing emphasis on network-level mechanisms and precision intervention. Functional connectivity is emerging as a potential biomarker for patient stratification and outcome prediction. Further progress depends on multicenter standardization, reproducible analytic pipelines, and high-quality comparative effectiveness research.

Facilitating Thought Progression: A Neurocognitive Framework Linking Thought Dynamics and Mood Disorders

Mood and thought are tightly coupled, but the mechanisms linking them are not understood. This link is particularly important when considering mood disorders such as depression. We propose the Facilitating Thought Progression (FTP) framework, which characterizes depression as a disorder of thought dynamics, encompassing both the temporal evolution and semantic expanse of mental activity. Five parameters jointly determine the fluency of thought progression: breadth, speed, flexibility, novelty, and scope.

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Combinatorial effects of multi-site stimulation on depression-related brain regions: clinical data analysis and predictive modeling

BackgroundDespite growing evidence supporting deep brain stimulation (DBS) for treatment- resistant depression (TRD), how stimulation delivered across hemispheres or across multiple targets interact to shape large-scale network activity remains poorly characterized.ObjectiveUsing a unique opportunity to simultaneously stimulate the subcallosal cingulate (SCC) and ventral capsule/ventral striatum (VC/VS) in subjects with TRD while recording neural activity across putative prefrontal networks underlying depression via intracranial electrodes, we investigated whether bilateral or multi-target stimulation has additive, synergistic/super-additive, or antagonistic/sub-additive effects on power modulation across depression-related brain networks.MethodsFour DBS leads, and ten stereo-electroencephalography (sEEG) leads were implanted in depression-related prefrontal brain regions in three subjects with TRD. Power modulation in response to unilateral and bilateral stimulation, as well as interaction classes of combinatorial stimulations, were evaluated across various combinations of frequency bands and region of interests (ROI) using marginal predictions from a linear mixed-effects model which were then used as input for machine learning classifiers to predict the additive interaction class of combinatorial stimulations.ResultsBilateral and multi-target stimulation produced additive or sub-additive interactions in most cases. A decision tree classifier identified ROI as the most important feature for predicting interaction class, followed by stimulation target and spectral frequency band.

Loss of Smell Therapies Informed by Olfactory Receptor Spatial Mapping

A new study published in Cell titled, “A spatial code governs olfactory receptor choice and aligns sensory maps in the nose and brain,” led by researchers from Harvard Medical School (HMS) has created the first detailed map of the spatial distribution of over 1,000 olfactory receptors in the epithelium. The study informs the development of therapies for loss of smell, where treatment options are limited.

The researchers examined approximately 5.5 million neurons in more than 300 individual mice using single-cell sequencing and spatial transcriptomics. Results showed that neurons are organized into tight, overlapping, horizontal stripes from the top to the bottom of the nose based on the type of smell receptor expressed. This highly organized receptor map was consistent across mouse models and mirrored the organization of smell maps in the brain. Similar maps have been observed in vision, hearing, and touch.

Notably, the olfactory map was informed by a gradient of retinoic acid in the nose, which allowed each neuron to express the correct type of smell receptor based on its spatial location.  

“Our results bring order to a system that was previously thought to lack order, which changes conceptually how we think this works,” said Sandeep (Robert) Datta, PhD, professor of neurobiology at HMS and senior author and corresponding author of the study. “We show that development can achieve this feat of organizing a thousand different smell receptors into an incredibly precise map that’s consistent across animals.” 

The authors also found that the receptor map in the nose matches up with smell maps in the olfactory bulb of the brain, shedding insight into how information moves from the nose to the brain. 

While sensory maps that describe how receptors in the eye, ear, and skin are organized to capture and interpret auditory, visual, and touch information, mapping olfactory receptors has been a longstanding challenge due to high receptor diversity. As an example, mice have approximately 20 million olfactory neurons that express more than a thousand types of smell receptors, compared with only three main types of visual receptors for color vision. Each type of smell receptor detects a unique subset of odor molecules. 

The team is also studying smell receptors in human tissue to understand to what degree the smell map is consistent across species to inform treatments, such as stem cell therapies and loss of smell and its consequences, such as an increased risk of depression. 

“Smell has a really profound and pervasive effect on human health, so restoring it is not just for pleasure and safety but also for psychological well-being,” Datta said. “Without understanding this map, we’re doomed to fail in developing new treatments.” 

The post Loss of Smell Therapies Informed by Olfactory Receptor Spatial Mapping appeared first on GEN – Genetic Engineering and Biotechnology News.

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<![CDATA[Lifestyle medicine pillars help reshape depression and anxiety treatment in psychiatry.]]>

Effects of bifrontal-transcranial direct current stimulation combined with music listening on sleep quality, cortical activation and functional connectivity in patients with insomnia: a randomised controlled trial by fNIRS

BackgroundAlthough music listening and transcranial direct current stimulation (tDCS) alone have certain effects in the treatment of insomnia, the sleep regulatory effects and neural mechanisms of the combined treatment in patients with insomnia disorder (ID) are unclear. This study aimed to investigate the efficacy of combined bifrontal-tDCS (F3: anode, F4: cathode) with music listening in patients with ID using functional near-infrared spectroscopy (fNIRS).Methods76 ID patients were randomly divided into an intervention group (n=38) and a control group (n=38), and received 4 weeks of a total of 20 sessions of music + tDCS therapy and music + sham tDCS therapy (30-second stimulation with fade-in/fade-out to mimic somatic sensations), respectively. The Pittsburgh Sleep Quality Index Scale (PSQI), Self-rating Depression Scale (SDS), Self-rating Anxiety Scale (SAS), and Perceived Stress Scale (PSS-14) were compared between the two groups before and after treatment. Oxy-haemoglobin (HbO2) concentration and functional connectivity (FC) were assessed during the verbal fluency task using fNIRS.ResultsCompared with the control group, the PSQI total score (mean difference: -2.57 points, 95% CI: -4.43 to -0.71, p = 0.001), PSQI sub-scores except “sleep disturbance and daytime dysfunction”, SDS and SAS scores of the intervention group improved significantly after treatment. It was observed by fNIRS that the HbO2 concentration in the medial prefrontal cortex (mPFC), left dorsolateral prefrontal cortex (DLPFC), right ventrolateral prefrontal cortex, and right superior frontal cortex (SFC) increased significantly after treatment in the intervention group but was not superior to the control group. In addition, the FC enhancement of left SFC-left DLPFC and left SFC-mPFC after treatment was significantly better in the intervention group than in the control group, and the PSQI improvement was positively correlated with the FC enhancement of channel-averaged and left SFC-right DLPFC.ConclusionsCombining bifrontal-tDCS with music listening is more helpful in improving sleep quality and prefrontal functional connectivity in ID patients compared with music listening alone. For ID patients, music electrical stimulation headphones may be a safe, effective, and convenient new treatment strategy.Clinical trial registrationhttps://www.chictr.org.cn/, identifier ChiCTR2400086233.

Acupoint temperature as a biomarker: infrared thermography in the diagnosis of adolescents with major depressive disorder

BackgroundThe prevalence of adolescent major depressive disorder (MDD) is rising; however, diagnosis relies on subjective measures due to a lack of objective biomarkers. This study explored infrared thermography (IRT) as a non-invasive tool to quantify thermal radiation characteristics of acupoints in adolescents with MDD. The objective was to establish diagnostic models based on acupoint temperature-derived biomarkers.MethodsA prospective, multi-center observational study enrolled 108 participants (65 adolescents with MDD and 43 healthy controls [HCs]). We first examined correlations between acupoint temperatures and depression severity using Pearson analysis. Multiple linear and binary logistic regression models were developed to diagnose MDD and assess severity. The diagnostic model for MDD was visualized as a nomogram and validated using Receiver Operating Characteristic (ROC) curves, Hosmer-Lemeshow tests, calibration plots, and decision curve analysis (DCA). Internal validation was performed using the bootstrap method.ResultsAmong 27 acupoints analyzed, adolescents with MDD exhibited altered acupoint temperatures at Taiyang (EX-HN5), Quchi (LI11), Yanggu (SI5), and Waiqiu (GB36). Subsequent Pearson correlation analysis revealed negative correlations between the infrared relative temperatures of Taiyang (EX-HN5), Quchi (LI11), and Waiqiu (GB36) and depression severity (P = 0.001, r = -0.319; P = 0.022, r = -0.229; P = 0.001, r = -0.325) and a weak positive correlation between the infrared relative temperature of Yanggu (SI5) and depression severity (P = 0.043, r = 0.202). Building on these findings, two diagnostic models were developed: a linear regression model for depression severity of adolescents (Y = 52.25-9.52*TEX-HN5-13.07*TGB36) and a logistic regression model for adolescents with MDD diagnosis (P = ex/(1+ex), x = 0.22-1.14*TEX-HN5+0.45*TSI5-2.19*TGB36). The nomogram-based model demonstrated good calibration (Hosmer-Lemeshow P = 0.855), discrimination (AUC = 0.785, 95%CI: 0.693 – 0.876), and clinical utility. Internal validation using the bootstrap method produced a C-index of 0.752 (95% CI: 0.617 – 0.877), further confirming the model’s robustness.ConclusionsIn conclusion, acupoint temperature-based models show promising efficacy for the objective and non-invasive diagnosis and severity quantification of adolescents with MDD, offering valuable tools for early clinical intervention. Future studies should validate these findings across diverse populations and integrate multi-modal biomarkers to enhance diagnostic precision.Clinical Trial RegistrationClinicalTrials.gov, identifier NCT06750640.

Prevalence of Cognitive Distortion Markers in a Suicide Prevention Chat Service: Mixed Methods Study

Background: Suicide helplines increasingly employ chat services to aid those in urgent need, but the wording and structure of text-driven exchanges may affect their effectiveness. Objective: Given the association of cognitive distortions with depression and anxiety, this study investigated their prevalence in the language of individuals seeking help from the Dutch 113 suicide helpline. Methods: We observed the prevalence of cognitive distortions for both help seekers and counselors in a large volume of chat sessions (N=71,148) of the Dutch 113 suicide chat helpline using natural language processing. The results were compared to 2 large collections of online text data from Dutch social media and web content. Results: We found that nearly all types of cognitive distortions are more prevalent in the language of help seekers compared to the control group of helpline counselors. Distortions of the personalizing, emotional reasoning, and mental filtering types were, respectively, 20.22, 7.87, and 4.53 times more prevalent among help seekers, revealing a distinct pattern of thought and language among individuals affected by suicidality. Conclusions: Our results raise the prospect of improving the effectiveness of online therapeutic interventions that target cognitive distortions through lexical analysis that detects the cognitive and lexical markers of suicidality.
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