Accelerated iTBS treatment applied to the left DLPFC in depressed patients results in a rapid volume increase in the left hippocampal dentate gyrus, not driven by brain perfusion

Hippocampal neurogenesis in adult primates: a systematic review

It had long been considered that no new neurons are generated in the primate brain beyond birth, but recent studies have indicated that neurogenesis persists in various locations throughout the lifespan. The dentate gyrus of the hippocampus is of particular interest due to the postulated role played by neurogenesis in memory. However, studies investigating the presence of adult hippocampal neurogenesis (AHN) have reported contradictory findings, and no systematic review of the evidence has been conducted to date. We searched MEDLINE, Embase and PsycINFO on 27th June 2023 for studies on hippocampal neurogenesis in adult primates, excluding review papers. Screening, quality assessment and data extraction was done by independent co-raters. We synthesised evidence from 112 relevant papers. We found robust evidence, primarily supported by immunohistochemical examination of tissue samples and neuroimaging, for newly generated neurons, first detected in the subgranular zone of the dentate gyrus, that mature over time and migrate to the granule cell layer, where they become functionally integrated with surrounding neuronal networks. AHN has been repeatedly observed in both humans and other primates and gradually diminishes with age. Transient increases in AHN are observed following acute insults such as stroke and epileptic seizures, and following electroconvulsive therapy, and AHN is diminished in neurodegenerative conditions. Markers of AHN correlate positively with measures of learning and short-term memory, but associations with antidepressant use and mood states are weaker. Heterogeneous outcome measures limited quantitative syntheses. Further research should better characterise the neuropsychological function of neurogenesis in healthy subjects.

Four weeks standard vs. one week accelerated intermittent Theta Burst Stimulation for the treatment of depression - A retrospective analysis

INTRODUCTION

Intermittent Theta Burst Stimulation (iTBS), a specific form of repetitive transcranial magnetic stimulation (rTMS) is increasingly used for treating affective disorders. Accelerated iTBS protocols (aiTBS) with shorter treatment duration may lead to equal but faster response rates compared to standard protocols.

METHODS

Here, we retrospectively analyzed the records of 66 rTMS in- and out-patients with major depressive disorder in a tertiary care hospital between April 2023 and September 2023. All patients received left prefrontal iTBS with 1200 pulses, either one session/workday over 4 weeks (n = 34) or left prefrontal aiTBS on five sessions/workday for one week (n = 32). Depressive symptoms were assessed with the 21-item Hamilton Depression Rating Scale (HAMD-21) and the Major Depression Inventory (MDI) before and at the end of the respective treatment.

RESULTS

With both treatments, iTBS and aiTBS, the severity of depression improved significantly according to HAMD-21 and MDI. Response rates for iTBS were 38 % (HAMD-21) and 35 % (MDI), for aiTBS 19 % (HAMD-21) and 16 % (MDI), respectively. Remission rates showed a similar pattern. Effect sizes for group differences were small to medium. No serious adverse events occurred in any group. Tolerability was lower in aiTBS. Overall satisfaction was low for aiTBS on a qualitative and subjective level.

CONCLUSION

aiTBS with 1200 pulses and five daily sessions lead to amelioration of symptoms within one week. But benefit, satisfaction, tolerability was slightly lower in contrast to four weeks of iTBS. For everyday clinical practice, aiTBS protocols can be considered after weighing up the logistical disadvantages, such as possible longer waiting time for new patients that want to start a therapy with TMS. Future studies should explore the optimal dosage regime (number of sessions per day, number of pulses per session) for fast and effective symptom reduction.

Antidepressant response time across intermittent theta burst stimulation regimens and efficacy indicators in adolescents depression: a secondary analysis from a randomized controlled trial

BACKGROUND

Accelerated intermittent theta burst stimulation (aiTBS), which involves the administration of multiple daily sessions of iTBS, represents a novel regimen of repetitive transcranial magnetic stimulation. Studies have suggested that aiTBS may facilitate a fast response among patients with major depressive disorders. However, whether aiTBS can accelerate antidepressant response in adolescents suffering from depression is still unclear. Additionally, the potential indicators associated with antidepressant response in this population are still understudied.

METHODS

Ninety adolescents with depression were recruited and randomly assigned to aiTBS (two 600-pulse sessions of iTBS spaced for 10 min, N = 31), iTBS (one 600-pulse session, N = 29), or sham iTBS (N = 30) for two treatment weeks. Kaplan-Meier analysis was used to estimate the mean time to antidepressant response among the three groups. The analysis of covariance and the multiple logistic regression were applied to identify potential indicators associated with treatment response.

RESULTS

The mean time to antidepressant response was 7.45 weeks (95% CI: 6.19-8.72) in the aiTBS group, 5.62 weeks (95% CI: 4.09-7.16) in the iTBS group, and 5.07 weeks (95% CI: 3.56-6.58) in the sham group, respectively. The log rank test revealed no significant difference in the mean time to antidepressant response among the three groups (χ2 = 4.156, p = 0.125). For the antidepressant response, there were also no significant interactions between iTBS treatment regimens and the baseline characteristics. Notably, participants with higher motor threshold and worse global function at baseline were likely to be associated with early response and final response, respectively, while those who experiencing child-parent separation were associated with both early and final response. In addition, younger participants were more likely to experience recurrence during follow-up.

CONCLUSIONS

aiTBS did not demonstrate an advantage in terms of a fast antidepressant response. However, some pretreatment characteristics might serve as indicators of antidepressant response. This relatively simple application based on pretreatment characteristics seems to be a cost-effective method to identify adolescents who are more likely to develop an early antidepressant response and sustain it.

TRIAL REGISTRATION

This is a secondary analysis of a primary RCT, which was officially registered in the Chinese Clinical Trial Registry at 19/1/2021 with the number of ChiCTR2100042346. https://www.chictr.org.cn/bin/project/edit?pid=66118 .

Comparative antidepressant effects and safety of intravenous racemic ketamine, psilocybin and theta burst stimulation for major depressive disorder: A systematic review and network meta-analyses of randomized controlled trials

The individual efficacy and safety of intravenous racemic (IV) ketamine, psilocybin, and theta burst stimulation (TBS) for major depressive disorder have been demonstrated through meta-analyses of randomized controlled trials (RCTs), but the comparative usefulness of these novel treatments has not yet been fully examined. We systematically searched the CENTRAL, Medline, CINHAL, and ClinicalTrials.gov databases for randomized controlled trials up to July 4, 2024. Random-effects network meta-analyses were conducted to compare the Comparative antidepressant effects and safety of intravenous racemic ketamine, psilocybin and theta burst stimulation for major depressive disorderantidepressant efficacy, tolerability, and acceptability of IV ketamine, psilocybin, and TBS. Twenty-eight RCTs were included. All treatments were superior to placebo, with IV ketamine and psilocybin showing significantly greater antidepressant efficacy than TBS. No significant differences were detected between all treatments and placebo in tolerability and acceptability. In a subgroup analysis focusing on short periods of 1 week or less, only IV ketamine was significantly more effective than placebo. In another subgroup analysis focusing on periods of 4 weeks or longer, IV ketamine and psilocybin showed significantly better antidepressant effects than placebo. The confidence in the evidence ranged from very low to moderate. Specifically, there is a scarcity of studies on psilocybin and a lack of direct comparison trials. The findings suggest that IV ketamine and psilocybin may be more effective treatments compared to TBS. Additionally, IV ketamine may have an advantage in terms of rapid onset of action. The number of included studies is limited, especially for psilocybin, and therefore the current findings are preliminary, necessitating further accumulation of direct-comparison RCTs.

Continuous theta burst stimulation for bipolar depression: A multicenter, double-blind randomized controlled study exploring treatment efficacy and predictive potential of kynurenine metabolites

BACKGROUND

While theta burst stimulation (TBS) shows promise in Major Depressive Disorder (MDD), its effectiveness in bipolar depression (BD-D) remains uncertain. Optimizing treatment parameters is crucial in the pursuit of rapid symptom relief. Moreover, aligning with personalized treatment strategies and increased interest in immunopsychiatry, biomarker-based stratification of patients most likely to benefit from TBS might improve remission rates. We investigated treatment effectiveness of continuous TBS (cTBS) compared to sham in BD-D, and assessed the capacity of plasma kynurenine pathway metabolites to predict treatment outcome.

METHODS

Thirty-seven patients with BD-D underwent accelerated active or sham cTBS treatment in a multicenter, double-blind, randomized controlled trial. Depressive symptoms were measured with the 17-item Hamilton Depression Rating Scale (HDRS-17) before treatment (T0), 3-4 days posttreatment (T1) and 10-11 days posttreatment (T2). Plasma tryptophan, kynurenine, kynurenic acid and quinolinic acid concentrations were quantified with ELISA. Linear mixed models were used for statistical analyses.

RESULTS

Although the total sample showed depressive symptom improvement, active cTBS did not demonstrate greater symptom alleviation compared to sham. However, higher baseline quinolinic acid significantly predicted symptom improvement in the active treatment group, not in sham-stimulated patients.

LIMITATIONS

The modest sample size limited the power to detect significant differences with regard to treatment effect. Also, the follow-up period was 10-11 days, whereas similar studies usually follow up for at least one month.

CONCLUSION

More research is required to optimize cTBS for BD-D and explore the involvement of quinolinic acid in treatment outcome.

Treatment expectations and clinical outcomes following repetitive transcranial magnetic stimulation for treatment-resistant depression

BACKGROUND

Patient expectations, including both positive (placebo) and negative (nocebo) effects, influence treatment outcomes, yet their impact on acute repetitive transcranial magnetic stimulation (rTMS) for treatment-resistant depression (TRD) is unclear.

METHODS

In this single-center retrospective chart review, 208 TRD patients completed the Stanford Expectation of Treatment Scale (SETS) before starting open-label rTMS treatment. Patients were offered two excitatory rTMS protocols (deep TMS or intermittent theta-burst stimulation), which stimulated the left dorsolateral prefrontal cortex. A minimum of 20 once daily treatments were provided, delivered over 4-6 weeks. Primary outcomes were 1) remission, measured by a post-treatment score of <8 on the Hamilton Depression Rating Scale (HAMD-17), and 2) premature discontinuation. The change in HAMD-17 scores over time was used as a secondary outcome. Physicians were blinded to SETS scores. Logistic and linear regression, adjusting for covariates, assessed SETS and HAMD-17 relationships.

RESULTS

Of 208 patients, 177 had baseline and covariate data available. The mean positivity bias score (positive expectancy minus negative expectancy subscale averages) was 0.48 ± 2.21, indicating the cohort was neutral regarding the expectations of their treatment on average. Higher positive expectancy scores were significantly associated with greater odds of remission (OR = 1.90, p = 0.003) and greater reduction in HAMD-17 scores (β = 1.30, p = 0.005) at the end of acute treatment, after adjusting for covariates. Negative expectancy was not associated with decreased odds of remission (p = 0.2) or treatment discontinuation (p = 0.8).

CONCLUSIONS

Higher pre-treatment positive expectations were associated with greater remission rates with open-label rTMS in a naturalistic cohort of patients with TRD.

Efficacy and Safety of Theta Burst Versus Repetitive Transcranial Magnetic Stimulation for the Treatment of Depression: A Meta-Analysis of Randomized Controlled Trials

OBJECTIVES

Theta burst stimulation (TBS) is more energy- and time-efficient than is standard repetitive transcranial magnetic stimulation (rTMS). However, further studies are needed to analyze TBS therapy for its efficacy and safety compared with standard rTMS in treating depression. The aim of this meta-analysis was to compare TBS therapy with standard rTMS treatment regarding their safety and therapeutic effect on individuals with depression.

MATERIALS AND METHODS

Six data bases (Wanfang, the China National Knowledge Infrastructure, PubMed, Embase, Cochrane Library, and PsycINFO) were searched from inception till December 20, 2022. Two independent reviewers selected potentially relevant studies on the basis of the inclusion criteria, extracted data, and evaluated the methodologic quality of the eligible trials using the modified ten-item Physiotherapy Evidence Database scale per Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Finally, ten comparable pairs of nine randomized controlled trials (RCTs) were included for meta-analysis. Summary odds ratios (ORs) of the rates of response, remission, and adverse events were simultaneously calculated using quality-effects (QE) and random-effects (RE) models. Changes in depression scores associated with antidepressant effects were expressed using standardized mean differences simultaneously. This study was registered with the International Prospective Register of Systematic Reviews (CRD42022376790).

RESULTS

Nine of the 602 RCTs, covering 1124 patients (616 who had TBS protocols applied vs 508 treated using standard rTMS), were included. Differences in response rates between the above two treatment modalities were not significant (OR = 1.01, 95% CI: 0.88-1.16, p = 0.44, I2 = 0%, RE model; OR = 1.07, 95% CI: 0.87-1.32, p = 0.44, I2 = 0%, QE model). Differences in adverse event rates between TBS and standard rTMS groups were not statistically significant.

CONCLUSIONS

TBS has similar efficacy and safety to standard rTMS for treating depression. Considering the short duration of daily stimulation sessions, this meta-analysis supports the continued development of TBS for treating depression.

Short-term and long-term efficacy of accelerated transcranial magnetic stimulation for depression: a systematic review and meta-analysis

BACKGROUND

In recent years, accelerated transcranial magnetic stimulation (aTMS) has been developed, which has a shortened treatment period. The aim of this study was to evaluate the efficacy and long-term maintenance effects of aTMS in patients with major depressive disorder (MDD).

METHODS

We systematically searched online databases for aTMS studies in patients with MDD published before February 2023 and performed a meta-analysis on the extracted data.

RESULTS

Four randomized controlled trials (RCTs) and 10 before-and-after controlled studies were included. The findings showed that depression scores significantly decreased following the intervention (SMD = 1.80, 95% CI (1.31, 2.30), p < 0.00001). There was no significant difference in antidepressant effectiveness between aTMS and standard TMS (SMD = -0.67, 95% CI (-1.62, 0.27), p = 0.16). Depression scores at follow-up were lower than those directly after the intervention based on the depression rating scale (SMD = 0.22, 95% CI (0.06, 0.37), p = 0.006), suggesting a potential long-term maintenance effect of aTMS. Subgroup meta-analysis results indicated that different modes of aTMS may have diverse long-term effects. At the end of treatment with the accelerated repetitive transcranial magnetic stimulation (arTMS) mode, depressive symptoms may continue to improve (SMD = 0.29, 95% CI (0.10, 0.49), I2 = 22%, p = 0.003), while the accelerated intermittent theta burst stimulation (aiTBS) mode only maintains posttreatment effects (SMD = 0.01, 95% CI (-0.45, 0.47), I2 = 66%, p = 0.98).

CONCLUSIONS

Compared with standard TMS, aTMS can rapidly improve depressive symptoms, but there is no significant difference in efficacy. aTMS may also have long-term maintenance effects, but longer follow-up periods are needed to assess this possibility.

TRIAL REGISTRATION

This article is original and not under simultaneous consideration for publication. The study was registered on PROSPERO ( https://www.crd.york.ac.uk/prospero/ ) (number: CRD42023406590).

Effects of a periodic intermittent theta burst stimulation in Alzheimer's disease

Background

Previous studies have demonstrated that excitatory repetitive transcranial magnetic stimulation (rTMS) can improve the cognitive function of patients with Alzheimer's disease (AD). Intermittent theta burst stimulation (iTBS) is a novel excitatory rTMS protocol for brain activity stimulation with the ability to induce long-term potentiation-like plasticity and represents a promising treatment for AD. However, the long-term effects of iTBS on cognitive decline and brain structure in patients with AD are unknown.

Aims

We aimed to explore whether repeating accelerated iTBS every three months could slow down the cognitive decline in patients with AD.

Methods

In this randomised, assessor-blinded, controlled trial, iTBS was administered to the left dorsolateral prefrontal cortex (DLPFC) of 42 patients with AD for 14 days every 13 weeks. Measurements included the Montreal Cognitive Assessment (MoCA), a comprehensive neuropsychological battery, and the grey matter volume (GMV) of the hippocampus. Patients were evaluated at baseline and after follow-up. The longitudinal pipeline of the Computational Anatomy Toolbox for SPM was used to detect significant treatment-related changes over time.

Results

The iTBS group maintained MoCA scores relative to the control group (t=3.26, p=0.013) and reduced hippocampal atrophy, which was significantly correlated with global degeneration scale changes. The baseline Mini-Mental State Examination (MMSE) score, apolipoprotein E genotype and Clinical Dementia Rating were indicative of MoCA scores at follow-up. Moreover, the GMV of the left (t=0.08, p=0.996) and right (t=0.19, p=0.977) hippocampus were maintained in the active group but significantly declined in the control group (left: t=4.13, p<0.001; right: t=5.31, p<0.001). GMV change in the left (r=0.35, p=0.023) and right (r=0.36, p=0.021) hippocampus across the intervention positively correlated with MoCA changes; left hippocampal GMV change was negatively correlated with global degeneration scale (r=-0.32, p=0.041) changes.

Conclusions

DLPFC-iTBS may be a feasible and easy-to-implement non-pharmacological intervention to slow down the progressive decline of overall cognition and quality of life in patients with AD, providing a new AD treatment option.

Trial registration number

NCT04754152.

Effects of intermittent theta-burst transcranial magnetic stimulation on cognition and hippocampal volumes in bipolar depression

INTRODUCTION

Repetitive transcranial magnetic stimulation (TMS) is increasingly used to treat neurocognitive symptoms in mood disorders. Intermittent theta burst stimulation (iTBS) is a brief version of TMS that may preferentially target cognitive functions. This study evaluated whether iTBS leads to cognitive improvements and associated increased hippocampal volumes in bipolar depression.

METHODS

In a two-site double-blind randomised sham controlled trial (NCT02749006), 16 patients received active iTBS to the Left Dorsolateral Prefrontal Cortex (DLPF) and 15 patients received sham stimulation across four weeks. A composite neuropsychological score and declarative memory scores served as the cognitive outcomes. Hippocampal volumes were derived from T1 weighted MRI scans using the longitudinal ComBat method to harmonise data across sites.

RESULTS

No significant improvements were observed in any cognitive variables in the active relative to the sham group; however, there was a trend for increased left hippocampal volume in the former. Left hippocampal volume increases were associated with improvements in nonverbal memory in the active group.

CONCLUSIONS

Although cognitive improvements were not associated with iTBS, the finding that hippocampal volume increases were associated with memory improvement suggests there may be some level of prefrontal-temporal neuroplasticity that could support cognitive change in future studies of iTBS in bipolar disorder.

Accelerated Repetitive Transcranial Magnetic Stimulation to Treat Major Depression: The Past, Present, and Future

Repetitive transcranial magnetic stimulation (rTMS) is an effective and evidence-based therapy for treatment-resistant major depressive disorder. A conventional course of rTMS applies 20-30 daily sessions over 4-6 weeks. The schedule of rTMS delivery can be accelerated by applying multiple stimulation sessions per day, which reduces the duration of a treatment course with a predefined number of sessions. Accelerated rTMS reduces time demands, improves clinical efficiency, and potentially induces faster onset of antidepressant effects. However, considerable heterogeneity exists across study designs. Stimulation protocols vary in parameters such as the stimulation target, frequency, intensity, number of pulses applied per session or over a course of treatment, and duration of intersession intervals. In this article, clinician-researchers and neuroscientists who have extensive research experience in accelerated rTMS synthesize a consensus based on two decades of investigation and development, from early studies ("Past") to contemporaneous theta burst stimulation, a time-efficient form of rTMS gaining acceptance in clinical settings ("Present"). We propose descriptive nomenclature for accelerated rTMS, recommend avenues to optimize therapeutic and efficiency potential, and suggest using neuroimaging and electrophysiological biomarkers to individualize treatment protocols ("Future"). Overall, empirical studies show that accelerated rTMS protocols are well tolerated and not associated with serious adverse effects. Importantly, the antidepressant efficacy of accelerated rTMS appears comparable to conventional, once daily rTMS protocols. Whether accelerated rTMS induces antidepressant effects more quickly remains uncertain. On present evidence, treatment protocols incorporating high pulse dose and multiple treatments per day show promise and improved efficacy.

Medial Prefrontal Cortex Theta Burst Stimulation Improves Treatment Outcomes in Alcohol Use Disorder: A Double-Blind, Sham-Controlled Neuroimaging Study

Background

Alcohol use disorder (AUD) is associated with elevated brain response to cues. Recent studies have suggested that theta burst stimulation (TBS) to the medial prefrontal cortex (MPFC) can decrease reactivity to cues in a transdiagnostic manner. The goal of this clinical trial was to evaluate the effect of continuous TBS as a tool to decrease drinking behavior and brain reactivity to alcohol cues among individuals with AUD.

Methods

A total of 50 individuals with AUD were recruited from an intensive outpatient treatment program. Using a randomized, double-blind, sham-controlled design, participants received 10 sessions of continuous TBS (left frontal pole, 1 session/10 days, 110% resting motor threshold, 3600 pulse/session, cue provocation before and during session). Brain reactivity to alcohol cues was acquired at four time points: at baseline and after all TBS sessions (1 month, 2 months, and 3 months).

Results

Overall, 80% of the participants completed all TBS sessions. Individuals who received real TBS were 2.71 times more likely to remain enrolled in the study after 3 months and 3.09 times more likely to remain sober 3 months after treatment initiation. Real TBS also led to a significantly greater reduction in brain reactivity to alcohol cues, specifically a reduction in MPFC-striatum and MPFC-insula connectivity 2 and 3 months after TBS treatment.

Conclusions

Ten days of MPFC TBS is well tolerated, reduces drinking, and decreases brain reactivity to alcohol cues for up to 3 months after treatment initiation. These results pave a critical next step in the path toward developing transcranial magnetic stimulation as an intervention for AUD and disorders associated with elevated cue reactivity.

Efficacy and tolerability of repetitive transcranial magnetic stimulation for late-life depression: A systematic review and meta-analysis

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) is a widely available treatment for major depression, but its efficacy and tolerability are uncertain for patients with late-life depression (LLD). To assess the existing evidence of rTMS for LLD treatment, we conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) according to PRISMA guidelines.

METHODS

We retrieved RCTs from four databases published between 1 January 2000 and 10 September 2021 comparing the effects of active and sham stimulation in LLD patients. We performed subgroup analyses to examine the impact of different parameters. The primary outcomes were the response and discontinuation rates of rTMS for LLD patients, representing for efficacy and tolerability, respectively. Secondary outcomes were remission and dropout rates. Discontinuation referred to patients who withdrew for any reason, while dropout referred to participants who withdrew early because of adverse events.

RESULTS

Nine articles describing 11 studies (two articles each contained two studies) met the eligibility criteria. All outcomes were analyzed using a random-effects model. The summary analysis of nine suitable RCTs revealed a cumulative response rate of 2.86 (95 % confidence interval (95 % CI), 1.87-4.37) and a remission rate of 4.02 (95 % CI, 1.83-8.81) in the active group compared to the sham group. The pooled odds ratios (ORs) for discontinuation and dropout rates were not significantly different between the two groups. In addition, some rTMS parameters were associated with better efficacy.

CONCLUSIONS

The meta-analysis suggested that rTMS is an effective, well-tolerated treatment for patients with LLD. Future efforts should enhance study methodologies to improve their efficacy and increase the homogeneity of rTMS parameters to promote comparability between studies.

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.

Accelerated low-intensity rTMS does not rescue anxiety behaviour or abnormal connectivity in young adult rats following chronic restraint stress

Currently approved repetitive transcranial magnetic stimulation (rTMS) protocols for the treatment of major depressive disorder (MDD) involve once-daily (weekday) stimulation sessions, with 10 Hz or intermittent theta burst stimulation (iTBS) frequencies, over 4-6 weeks. Recently, accelerated treatment protocols (multiple daily stimulation sessions for 1-2 weeks) have been increasingly studied to optimize rTMS treatments. Accelerated protocols might confer unique advantages for adolescents and young adults but there are many knowledge gaps related to dosing in this age group. Off-label, clinical practice frequently outpaces solid evidence as rigorous clinical trials require substantial time and resources. Murine models present an opportunity for high throughput dose finding studies to focus subsequent clinical trials in humans. This project investigated the brain and behavioural effects of an accelerated low-intensity rTMS (LI-rTMS) protocol in a young adult rodent model of chronic restraint stress (CRS). Depression and anxiety-related behaviours were induced in young adult male Sprague Dawley rats using the CRS model, followed by the 3-times-daily delivery of 10 Hz LI-rTMS, for two weeks. Behaviour was assessed using the Elevated Plus Maze and Forced Swim Test, and functional, chemical, and structural brain changes measured using magnetic resonance imaging techniques. CRS induced an agitated depression-like phenotype but therapeutic effects from the accelerated protocol were not detected. Our findings suggest that the age of rodents may impact response to CRS and LI-rTMS. Future studies should also examine higher intensities of rTMS and accelerated theta burst protocols.

A transdiagnostic review of safety, efficacy, and parameter space in accelerated transcranial magnetic stimulation

BACKGROUND

Accelerated transcranial magnetic stimulation (aTMS) is an emerging delivery schedule of repetitive TMS (rTMS). TMS is "accelerated" by applying two or more stimulation sessions within a day. This three-part review comprehensively reports the safety/tolerability, efficacy, and stimulation parameters affecting response across disorders.

METHODS

We used the PubMed database to identify studies administering aTMS, which we defined as applying at least two rTMS sessions within one day.

RESULTS

Our targeted literature search identified 85 aTMS studies across 18 diagnostic and healthy control groups published from July 2001 to June 2022. Excluding overlapping populations, 63 studies delivered 43,873 aTMS sessions using low frequency, high frequency, and theta burst stimulation in 1543 participants. Regarding safety, aTMS studies had similar seizure and side effect incidence rates to those reported for once daily rTMS. One seizure was reported from aTMS (0.0023% of aTMS sessions, compared with 0.0075% in once daily rTMS). The most common side effects were acute headache (28.4%), fatigue (8.6%), and scalp discomfort (8.3%), with all others under 5%. We evaluated aTMS efficacy in 23 depression studies (the condition with the most studies), finding an average response rate of 42.4% and remission rate of 28.4% (range = 0-90.5% for both). Regarding parameters, aTMS studies ranged from 2 to 10 sessions per day over 2-30 treatment days, 10-640 min between sessions, and a total of 9-104 total accelerated TMS sessions per participant (including tapering sessions). Qualitatively, response rate tends to be higher with an increasing number of sessions per day, total sessions, and total pulses.

DISCUSSION

The literature to date suggests that aTMS is safe and well-tolerated across conditions. Taken together, these early studies suggest potential effectiveness even in highly treatment refractory conditions with the added potential to reduce patient burden while also expediting response time. Future studies are warranted to systematically investigate how key aTMS parameters affect treatment outcome and durability.

Accelerated iTBS changes perfusion patterns in medication resistant depression

Accelerated intermittent Theta Burst Stimulation (aiTBS) is a new non-invasive brain stimulation protocol developed to rapidly treat medication resistant depression (MRD). However, to examine potential neurobiological changes only few sham-controlled studies combining pre/post treatment measures and brain imaging data are available. Consequently, with this Arterial Spin Labeling (ASL) brain imaging study, we investigated in 45 antidepressant-free MRD patients whether clinical improvement following aiTBS treatment applied to the left dorsolateral prefrontal cortex (Trial registration: http://clinicaltrials.gov/show/NCT01832805) would be associated with specific changes in brain perfusion patterns. We primarily expected frontolimbic perfusion changes following active and not sham aiTBS. Our ASL brain imaging findings showed that active aiTBS resulted in prompt perfusion increases in functionally connected brain regions such as the ventromedial prefrontal cortex and the right inferior parietal lobule. We also observed decreased perfusion in the left parahippocampal gyrus and the right posterior cerebellar lobe after active aiTBS. On the other hand, sham aiTBS resulted in right angular perfusion decreases, an area known to be involved in placebo responses. Overall, our perfusion findings indicate that active aiTBS treatment promptly affects brain regions functionally and structurally connected to the stimulated area and known to be part of deregulated brain circuits when clinically depressed. Placebo responses may be part of the clinical effects of accelerated ITS protocols. Our current results further shed light on how accelerated rTMS treatment protocols may promptly improve depressive symptoms in MRD.

The Impact of Accelerated HF-rTMS on Canine Brain Metabolism: An [18F]-FDG PET Study in Healthy Beagles

Background

Repetitive transcranial magnetic stimulation (rTMS) has been proven to be a useful tool for the treatment of several severe neuropsychiatric disorders. Accelerated (a)rTMS protocols may have the potential to result in faster clinical improvements, but the effects of such accelerated paradigms on brain function remain to be elucidated.

Objectives

This sham-controlled arTMS study aimed to evaluate the immediate and delayed effects of accelerated high frequency rTMS (aHF-rTMS) on glucose metabolism in healthy beagle dogs when applied over the left frontal cortex.

Methods

Twenty-four dogs were randomly divided into four unequal groups: five active (n = 8)/ sham (n = 4) stimulation sessions (five sessions in 1 day), 20 active (n = 8)/ sham (n = 4) stimulation sessions (five sessions/ day for 4 days), respectively. [¹⁸F] FDG PET scans were obtained at baseline, 24 h poststimulation, after 1 and 3 months post the last stimulation session. We explicitly focused on four predefined regions of interest (left/right prefrontal cortex and left/right hippocampus).

Results

One day of active aHF-rTMS- and not sham- significantly increased glucose metabolism 24 h post-active stimulation in the left frontal cortex only. Four days of active aHF-rTMS only resulted in a nearly significant metabolic decrease in the left hippocampus after 1 month.

Conclusions

Like in human psychiatric disorders, active aHF-rTMS in healthy beagles modifies glucose metabolism, although differently immediately or after 1 month post stimulation. aHF-rTMS may be also a valid option to treat mentally disordered dogs.

Insight Into the Effects of Clinical Repetitive Transcranial Magnetic Stimulation on the Brain From Positron Emission Tomography and Magnetic Resonance Imaging Studies: A Narrative Review

Repetitive transcranial magnetic stimulation (rTMS) has been proposed as a therapeutic tool to alleviate symptoms for neurological and psychiatric diseases such as chronic pain, stroke, Parkinson’s disease, major depressive disorder, and others. Although the therapeutic potential of rTMS has been widely explored, the neurological basis of its effects is still not fully understood. Fortunately, the continuous development of imaging techniques has advanced our understanding of rTMS neurobiological underpinnings on the healthy and diseased brain. The objective of the current work is to summarize relevant findings from positron emission tomography (PET) and magnetic resonance imaging (MRI) techniques evaluating rTMS effects. We included studies that investigated the modulation of neurotransmission (evaluated with PET and magnetic resonance spectroscopy), brain activity (evaluated with PET), resting-state connectivity (evaluated with resting-state functional MRI), and microstructure (diffusion tensor imaging). Overall, results from imaging studies suggest that the effects of rTMS are complex and involve multiple neurotransmission systems, regions, and networks. The effects of stimulation seem to not only be dependent in the frequency used, but also in the participants characteristics such as disease progression. In patient populations, pre-stimulation evaluation was reported to predict responsiveness to stimulation, while post-stimulation neuroimaging measurements showed to be correlated with symptomatic improvement. These studies demonstrate the complexity of rTMS effects and highlight the relevance of imaging techniques.

Biophysical mechanisms of electroconvulsive therapy-induced volume expansion in the medial temporal lobe: A longitudinal in vivo human imaging study

Background:

Electroconvulsive therapy (ECT) applies electric currents to the brain to induce seizures for therapeutic purposes. ECT increases gray matter (GM) volume, predominantly in the medial temporal lobe (MTL). The contribution of induced seizures to this volume change remains unclear.

Methods:

T1-weighted structural MRI was acquired from thirty patients with late-life depression (mean age 72.5 ± 7.9 years, 19 female), before and one week after one course of right unilateral ECT. Whole brain voxel-/deformation-/surface-based morphometry analyses were conducted to identify tissue-specific (GM, white matter: WM), and cerebrospinal fluid (CSF) and cerebral morphometry changes following ECT. Whole-brain voxel-wise electric field (EF) strength was estimated to investigate the association of EF distribution and regional brain volume change. The association between percentage volume change in the right MTL and ECT-related parameters (seizure duration, EF, and number of ECT sessions) was investigated using multiple regression.

Results:

ECT induced widespread GM volume expansion with corresponding contraction in adjacent CSF compartments, and limited WM change. The regional EF was strongly correlated with the distance from the electrodes, but not with regional volume change. The largest volume expansion was identified in the right MTL, and this was correlated with the total seizure duration.

Conclusions:

Right unilateral ECT induces widespread, bilateral regional volume expansion and contraction, with the largest change in the right MTL. This dynamic volume change cannot be explained by the effect of electrical stimulation alone and is related to the cumulative effect of ECT-induced seizures.

Cognitive behavioral based group psychotherapy focusing on repetitive negative thinking: Decreased uncontrollability of rumination is related to brain perfusion increases in the left dorsolateral prefrontal cortex

Repetitive negative thinking (RNT) is a core process underlying various psychiatric disorders. 'Uncontrollability of rumination (UOR)' is one the most maladaptive factors of rumination, but little is known on how cognitive behavioral focused RNT psychotherapy may alter brain activity. In a subsample of 47 patients suffering from RNT who also underwent brain imaging (registered RCT trial NCT01983033), we evaluated the effect of cognitive behavioral based group psychotherapy (CBGP) (n = 25) as compared to a delayed treatment control group (DTCG) (n = 22) on frontolimbic brain perfusion with a focus on UOR. This RNT construct was measured using the subscale 'uncontrollability' of the Dutch version of the Rumination on Sadness Scale (LARSS-U). Brain perfusion was assessed with arterial spin labeling (ASL)-fMRI. LARSS-U scale scores significantly decreased in the CBGP cohort whereas no significant changes emerged in the DTCG group. Compared to the DTCG, this decrease on UOR in the CBGP group was related to significant perfusion increases in the left (dorsolateral) prefrontal cortex, part of the executive network. Besides the fact that CBGP significantly reduced RNT, this attenuation of uncontrollable ruminative thoughts was related to brain perfusion increases areas documented to be involved in the top down control of adaptive emotion regulation and the inhibition of ruminative processes.

The intervention, the patient and the illness - Personalizing non-invasive brain stimulation in psychiatry

Current hypotheses on the therapeutic action of non-invasive brain stimulation (NIBS) in psychiatric disorders build on the abundant data from neuroimaging studies. This makes NIBS a very promising tool for developing personalized interventions within a precision medicine framework. NIBS methods fundamentally vary in their neurophysiological properties. They comprise repetitive transcranial magnetic stimulation (rTMS) and its variants (e.g. theta burst stimulation - TBS) as well as different types of transcranial electrical stimulation (tES), with the largest body of evidence for transcranial direct current stimulation (tDCS). In the last two decades, significant conceptual progress has been made in terms of NIBS targets, i.e. from single brain regions to neural circuits and to functional connectivity as well as their states, recently leading to brain state modulating closed-loop approaches. Regarding structural and functional brain anatomy, NIBS meets an individually unique constellation, which varies across normal and pathophysiological states. Thus, individual constitutions and signatures of disorders may be indistinguishable at a given time point, but can theoretically be parsed along course- and treatment-related trajectories. We address precision interventions on three levels: 1) the NIBS intervention, 2) the constitutional factors of a single patient, and 3) the phenotypes and pathophysiology of illness. With examples from research on depressive disorders, we propose solutions and discuss future perspectives, e.g. individual MRI-based electrical field strength as a proxy for NIBS dosage, and also symptoms, their clusters, or biotypes instead of disorder focused NIBS. In conclusion, we propose interleaved research on these three levels along a general track of reverse and forward translation including both clinically directed research in preclinical model systems, and biomarker guided controlled clinical trials. Besides driving the development of safe and efficacious interventions, this framework could also deepen our understanding of psychiatric disorders at their neurophysiological underpinnings.

Cortical Thickness in the Right Anterior Cingulate Cortex Relates to Clinical Response to Left Prefrontal Accelerated Intermittent Theta Burst Stimulation: An Exploratory Study

Objectives

Accelerated intermittent theta burst stimulation (aiTBS) is a promising treatment option for depressed patients. However, there is a large interindividual variability in clinical effectiveness and individual biomarkers to guide treatment outcome are needed.

Materials and Methods

Here, the relation between cortical thickness and clinical response (17‐item Hamilton Depression Rating Scale) was studied using anatomical MRI data of 50 depressed patients who were included in a randomized, sham‐controlled, double‐blinded, cross‐over aiTBS design (NCT01832805).

Results

Baseline cortical thickness in the right caudal part of the anterior cingulate cortex (cACC) was significantly correlated with direct clinical responses in the subgroup who received active aiTBS during the first stimulation week. No correlations were found between baseline cortical thickness and delayed clinical effectiveness. In this particular region, longitudinal changes in cortical thickness were significantly correlated with clinical effectiveness. Furthermore, direct changes in cortical thickness in the right cACC showed predictive potential of delayed clinical responses.

Conclusion

Cortical thickness within the right cACC might be an important biomarker to predict clinical responses to aiTBS. Additional studies are warranted to substantiate the specific biomarker potential of these parts of the ACC.