Large-scale analysis of interindividual variability in single and paired-pulse TMS data

OBJECTIVE

This study brought together over 60 transcranial magnetic stimulation (TMS) researchers to create the largest known sample of individual participant single and paired-pulse TMS data to date, enabling a more comprehensive evaluation of factors driving response variability.

METHODS

Authors of previously published studies were contacted and asked to share deidentified individual TMS data. Mixed-effects regression investigated a range of individual and study level variables for their contribution to variability in response to single and paired-pulse TMS data.

RESULTS

687 healthy participant's data were pooled across 35 studies. Target muscle, pulse waveform, neuronavigation use, and TMS machine significantly predicted an individual's single-pulse TMS amplitude. Baseline motor evoked potential amplitude, motor cortex hemisphere, and motor threshold (MT) significantly predicted short-interval intracortical inhibition response. Baseline motor evoked potential amplitude, test stimulus intensity, interstimulus interval, and MT significantly predicted intracortical facilitation response. Age, hemisphere, and TMS machine significantly predicted MT.

CONCLUSIONS

This large-scale analysis has identified a number of factors influencing participants' responses to single and paired-pulse TMS. We provide specific recommendations to minimise interindividual variability in single and paired-pulse TMS data.

SIGNIFICANCE

This study has used large-scale analyses to give clarity to factors driving variance in TMS data. We hope that this ongoing collaborative approach will increase standardisation of methods and thus the utility of single and paired-pulse TMS.

Resting-state electroencephalographic functional network alterations in major depressive disorder following magnetic seizure therapy

Magnetic seizure therapy (MST) is emerging as a safe and well-tolerated experimental intervention for major depressive disorder (MDD), with very minimal cognitive side-effects. However, the underlying mechanism of action of MST remains uncertain. Here, we used resting-state electroencephalography (RS-EEG) to characterise the physiological effects of MST for treatment resistant MDD. We recorded RS-EEG in 21 patients before and after an open label trial of MST applied over the prefrontal cortex using a bilateral twin coil. RS-EEG was analysed for changes in functional connectivity, network topology, and spectral power. We also ran further baseline comparisons between the MDD patients and a cohort of healthy controls (n = 22). Network-based connectivity analysis revealed a functional subnetwork of significantly increased theta connectivity spanning frontal and parieto-occipital channels following MST. The change in theta connectivity was further found to predict clinical response to treatment. An additional widespread subnetwork of reduced beta connectivity was also elucidated. Graph-based topological analyses showed an increase in functional network segregation and reduction in integration in the theta band, with a decline in segregation in the beta band. Finally, delta and theta power were significantly elevated following treatment, while gamma power declined. No baseline differences between MDD patients and healthy subjects were observed. These results highlight widespread changes in resting-state brain dynamics following a course of MST in MDD patients, with changes in theta connectivity providing a potential physiological marker of treatment response. Future prospective studies are required to confirm these initial findings.

Targeting repetitive transcranial magnetic stimulation in depression: do we really know what we are stimulating and how best to do it?

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) is an established treatment for patients with depression who have not achieved optimal outcomes with one or more trials of antidepressant medication. It is an effective antidepressant treatment but there remains considerable scope for improving clinical outcomes. One method to potentially enhance the efficacy of rTMS is through the improvement of methods of stimulation localization.

OBJECTIVE

The purpose of this paper is to review the literature pertaining to rTMS localization methods and approaches relevant to the treatment of major depressive disorder (MDD) and provide specific opinions on the state of the art in regards to targeting of rTMS treatment in depression.

METHODS

A targeted review of the literature on rTMS targeting in depression.

RESULTS

There is emerging evidence that optimal rTMS treatment outcomes are likely to be achieved with stimulation at a relatively anterior stimulation site in the left dorsolateral prefrontal cortex (DLPFC). However, some lines of research suggest that there may be two effective stimulation sites: one quite posterior, and one more anterior, in the DLPFC. The 'Beam F3' method provides reasonable localization to the anterior stimulation site and the posterior stimulation site corresponds to that typically used in studies using the '5 cm method'. Neuro-navigational methods are generally most likely to consistently ensure placement of the TMS coil such that it results in stimulation of a selected cortical site. fMRI - connectivity based approaches to targeting specific circuits in the DLPFC are intellectually attractive but it may not be possible to demonstrate differential effectiveness of these over the methods most commonly been used in clinical practice.

CONCLUSIONS

There is an emerging literature helping to improve our understanding of the optimal methods for targeting rTMS treatment for depression. However, we lack substantive prospective clinical trials demonstrating improved clinical outcomes with these techniques.

Neural activity during cognitive reappraisal in chronic low back pain: a preliminary study

OBJECTIVES

Chronic pain patients often report higher levels of negative emotions, suggesting reduced ability to regulate emotions effectively, however, little is known of the underlying neural cognitive mechanisms. Therefore, the aim of this study was to explore brain activity and connectivity during cognitive reappraisal in chronic low back pain (CLBP).

METHODS

This study recruited 24 female participants; 12 with CLBP and 12 healthy controls. Participants completed an emotion regulation task that involved cognitive reappraisal of negative images during functional magnetic resonance imaging. The negative affect following each image and perceived success of the task were reported. Region of interest and seed-to-voxel analyses were conducted using key regions involved in cognitive reappraisal (i.e., amygdalae and dorsomedial prefrontal cortex) as seed regions.

RESULTS

During the task, there were no group differences in the behavioural measures and blood oxygen level-dependent (BOLD) brain activation in the seed regions. Functional connectivity analysis showed reduced coupling between the amygdalae and dorsolateral prefrontal cortex, orbitofrontal cortex and inferior parietal cortex in the CLBP group compared to controls. Connectivity between the amygdala and inferior parietal cortex positively correlated with the percent of reduced negative affect during reappraisal in the CLBP group.

CONCLUSIONS

These preliminary findings demonstrate that individuals with CLBP exhibit similar emotion regulation abilities to healthy controls at the behavioural and BOLD level. However, altered functional connectivity observed in the CLBP group may reduce effective cognitive reappraisal. These results provide evidence for the potential clinical impact of network changes in CLBP.

The place of non-invasive brain stimulation in the RANZCP clinical practice guidelines for mood disorders

Clinical practice guidelines are important documents as they have the capacity to significantly influence and shape clinical practice in important areas of therapeutics. As such, they need to be developed informed by comprehensive and quality-based systematic reviews, involve consensus deliberations representative of the appropriate experts in the field and be subject to thorough critical review. A revised clinical practice guideline for the management of patients with mood disorders was recently published under the auspices of the Royal Australian and New Zealand College of Psychiatrists. However, this clinical practice guideline was not developed in a manner that reflects the appropriate standards that should apply to clinical practice guideline development and it has critical flaws, especially as it pertains to the use of repetitive transcranial magnetic stimulation treatment for patients with depression. The revision of the college clinical practice guideline has explicitly removed clear and unequivocal evidence-based recommendations that were found in a previous version of the clinical practice guideline and replaced these with consensus-based recommendations. However, the consensus-based recommendations were developed without consultation of the appropriate expert body within the college and contradict the scientific literature. There is substantive and unequivocal evidence supporting the antidepressant use of repetitive transcranial magnetic stimulation in the treatment of patients with depression and its use after a patient with depression has failed a limited number (typically around two) of antidepressant medication trials. Readers should refer to the college Professional Practice Guidelines for repetitive transcranial magnetic stimulation published in 2018 for thorough information about the use of this important new treatment.

Left handedness and response to repetitive transcranial magnetic stimulation in major depressive disorder

OBJECTIVES

Considerable research has demonstrated the efficacy of repetitive transcranial magnetic stimulation treatment (rTMS) in patients with major depressive disorder (MDD) with differences in effects related to laterality of stimulation. However, no systematic research has explored whether left-handed subjects respond in the same way as right-handed subjects.

METHODS

Data from 6 clinical trials (n = 310) were pooled and we explored whether left-handed patients with MDD responded in a similar manner to rTMS, including how they responded to both high-frequency left and low-frequency right-sided forms of treatment.

RESULTS

Overall, patients with MDD who were left-handed responded to a greater degree than right-handed patients to rTMS therapy. On subgroup analysis, notably limited by small numbers in the left handed groups, this effect was seen with high-frequency left-sided treatment but not with low-frequency right-sided treatment. The overall effect of a greater response in left-handed patients was not attributable to other clinical or study variables.

CONCLUSIONS

Standard forms of rTMS treatment appear to be effective in patients with MDD who are left-handed and there seems no justification for modifying the laterality of treatment application in these patients.

Effects of repetitive transcranial magnetic stimulation on suicidal behavior: A systematic review

The efficacy and tolerability of repetitive transcranial magnetic stimulation (rTMS) in major depression is well-known and documented by existing studies. However, whether rTMS may be effective on suicidal behavior is unclear and needs to be further investigated. This systematic review is aimed to investigate the available literature about the effects of rTMS on suicidal behavior and provide a comprehensive overview of the available evidence. A systematic search regarding the association between rTMS and suicidal behavior was carried out. All relevant articles concerning this association were comprehensively searched on PubMed, Scopus, Science Direct, and PsycInfo databases. After a careful search, 16 articles (7 sham-controlled studies, 5 uncontrolled studies, 4 case-series) met inclusion criteria and were selected in this systematic review. Overall, the left dorsolateral prefrontal cortex (DLPFC) was identified as the most frequent stimulation target by most studies. Unfortunately, actually it is not clear whether suicidal behavior reduction may be mediated, at least in some cases, by depression attenuation. While some methodological heterogeneity was found in terms of stimulation parameters (e.g., frequency, number of sessions, intensity of stimulation), most of the analyzed articles showed that rTMS is a safe, applicable, well tolerated and reproducible method in treating suicidal behavior. The most effective treatment seems to be the bilateral rTMS as well as the combination with antidepressants. Further longitudinal studies are required in order to replicate the mentioned study results.

Functional Magnetic Resonance Imaging-Guided Personalization of Transcranial Magnetic Stimulation Treatment for Depression

This study assesses whether treatment response for depression could be improved via a single one-site-fits-all dorsolateral prefrontal cortex target, representing the group average optimal site of subgenual cingulate cortex functional connectivity, or whether target site personalization is necessary.

Personalized connectivity-guided DLPFC-TMS for depression: Advancing computational feasibility, precision and reproducibility

Repetitive transcranial magnetic stimulation (rTMS) of the dorsolateral prefrontal cortex (DLPFC) is an established treatment for refractory depression, however, therapeutic outcomes vary. Mounting evidence suggests that clinical response relates to functional connectivity with the subgenual cingulate cortex (SGC) at the precise DLPFC stimulation site. Critically, SGC-related network architecture shows considerable interindividual variation across the spatial extent of the DLPFC, indicating that connectivity-based target personalization could potentially be necessary to improve treatment outcomes. However, to date accurate personalization has not appeared feasible, with recent work indicating that the intraindividual reproducibility of optimal targets is limited to 3.5 cm. Here we developed reliable and accurate methodologies to compute individualized connectivity-guided stimulation targets. In resting-state functional MRI scans acquired across 1,000 healthy adults, we demonstrate that, using this approach, personalized targets can be reliably and robustly pinpointed, with a median accuracy of ~2 mm between scans repeated across separate days. These targets remained highly stable, even after 1 year, with a median intraindividual distance between coordinates of only 2.7 mm. Interindividual spatial variation in personalized targets exceeded intraindividual variation by a factor of up to 6.85, suggesting that personalized targets did not trivially converge to a group-average site. Moreover, personalized targets were heritable, suggesting that connectivity-guided rTMS personalization is stable over time and under genetic control. This computational framework provides capacity for personalized connectivity-guided TMS targets to be robustly computed with high precision and has the flexibly to advance research in other basic research and clinical applications.

A pilot study of magnetic seizure therapy for treatment-resistant obsessive-compulsive disorder

BACKGROUND

There is growing interest in the potential of neuromodulation options in treatment-resistant obsessive-compulsive disorder (OCD). Magnetic seizure therapy (MST), is a new treatment intervention in which generalized seizures are induced with transcranial magnetic stimulation. We conducted a pilot study to assess the efficacy and cognitive effects of MST in patients with treatment-resistant OCD.

METHODS

In an open-label pilot study, participants with treatment-resistant OCD and a baseline Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) scores of ≥16 were treated with up to 24 acute treatments. The primary clinical outcomes were clinical response (Y-BOCS score reduction ≥30%) and remission (final Y-BOCS score ≤8). A neurocognitive battery, the Quick Inventory for Depressive Symptoms-Self Report (QIDS-SR), the Beck Scale for Suicidal Ideation (SSI), and the Quality of Life Enjoyment and Satisfaction Questionnaire-Short Form (Q-LES-Q-SF) were also completed as secondary measures.

RESULTS

Ten participants with OCD who had not responded to medications or psychotherapy enrolled in the study and seven completed an adequate trial (defined as ≥8 treatments). MST was associated with minimal cognitive effects except for some decrease in autobiographical memory and no serious adverse effects. Only one participant met the predefined criteria for response, and none for remission. The baseline and endpoint Y-BOCS scores were not statistically different.

CONCLUSION

Overall, MST was not beneficial in a small group of patients with treatment-resistant OCD. At this time, other studies of MST for OCD are not warranted until different coil placements targeting other brain circuits can be proposed.

Translating Psychedelic Therapies From Clinical Trials to Community Clinics: Building Bridges and Addressing Potential Challenges Ahead

Research exploring the potential of psychedelic-assisted therapies to treat a range of mental illnesses is flourishing, after the problematic sociopolitical history of psychedelics led to the shutdown of clinical research for almost 40 years. Encouraged by positive results, clinicians and patients are now hopeful that further interruptions to research will be avoided, so that the early promise of these therapies might be fulfilled. At this early stage of renewed interest, researchers are understandably focusing more on clinical trials to investigate safety and efficacy, than on longer-term goals such as progression to community practice. Looking to identify and avoid potential pitfalls on the path to community clinics, the authors, a group of Australian clinicians and researchers, met to discuss possible obstacles. Five broad categories of challenge were identified: 1) inherent risks; 2) poor clinical practice; 3) inadequate infrastructure; 4) problematic perceptions; and 5) divisive relationships and fractionation of the field. Our analysis led us to propose some strategies, including public sector support of research and training to establish best practice and optimize translation, and funding to address issues of equitable access to treatment. Above all, we believe that strategic planning and professional cohesion will be crucial for success. Accordingly, our key recommendation is the establishment of a multidisciplinary advisory body, broadly endorsed and representing all major stakeholders, to guide policy and implementation of psychedelic-assisted therapies in Australia. Although these challenges and strategies are framed within the Australian context, we sense that they may generalize to other parts of the world. Wherever they apply, we believe that anticipation of potential difficulties, and creative responses to address them, will be important to avoid roadblocks in the future and keep the "psychedelic renaissance" on track.

Individual alpha frequency proximity associated with repetitive transcranial magnetic stimulation outcome: An independent replication study from the ICON-DB consortium

OBJECTIVE

The aim of the current study was to attempt to replicate the finding that the individual alpha frequency (IAF) as well as the absolute difference between IAF and 10 Hz stimulation frequency (IAF-prox) is related to treatment outcome.

METHODS

Correlations were performed to investigate the relationship between IAF-prox and percentage symptom improvement in a sample of 153 patients with major depressive disorder treated with 10 Hz (N = 59) to the left dorsolateral prefrontal cortex (DLPFC) or 1 Hz (N = 94) to the right DLPFC repetitive Transcranial Magnetic Stimulation (rTMS).

RESULTS

There was a significant negative correlation between IAF-prox and the percentage of symptom improvement only for the 10 Hz group. Curve fitting models revealed that there was a quadratic association between IAF and treatment response in the 10 Hz group, with a peak at 10 Hz IAF.

CONCLUSION

The main result of Corlier and colleagues was replicated, and the findings suggest that the distance between 10 Hz stimulation frequency and the IAF may influence clinical outcome in a non-linear manner.

SIGNIFICANCE

rTMS is often administered at a frequency of 10 Hz, which is the center of the EEG alpha frequency band. The results can make a significant contribution to optimizing the clinical application of rTMS.

Subgenual cingulate connectivity and hippocampal activation are related to MST therapeutic and adverse effects

Aberrant connectivity between the dorsolateral prefrontal cortex (DLPFC) and the subgenual cingulate cortex (SGC) has been linked to the pathophysiology of depression. Indirect evidence also links hippocampal activation to the cognitive side effects of seizure treatments. Magnetic seizure therapy (MST) is a novel treatment for patients with treatment resistant depression (TRD). Here we combine transcranial magnetic stimulation with electroencephalography (TMS-EEG) to evaluate the effects of MST on connectivity and activation between the DLPFC, the SGC and hippocampus (Hipp) in patients with TRD. The TMS-EEG was collected from 31 TRD patients prior to and after an MST treatment trial. Through TMS-EEG methodology we evaluated significant current scattering (SCS) as an index of effective connectivity between the SGC and left DLPFC. Significant current density (SCD) was used to assess activity at the level of the Hipp. The SCS between the SGC and DLPFC was reduced after the course of MST (p < 0.036). The DLPFC-SGC effective connectivity reduction correlated with the changes in Hamilton depression score pre-to-post treatment (R = 0.46; p < 0.031). The SCD localized to the Hipp was reduced after the course of MST (p < 0.015), and the SCD change was correlated with montreal cognitive assessment (MOCA) scores pre-post the course of MST (R = -0.59; p < 0.026). Our findings suggest that MST treatment is associated with SGC-DLPFC connectivity reduction and that changes to cognition are associated with Hipp activation reduction. These findings demonstrate two distinct processes which drive efficacy and side effects separately, and might eventually aid in delineating physiological TRD targets in clinical settings.

An update on the clinical use of repetitive transcranial magnetic stimulation in the treatment of depression

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) is an increasingly used treatment for patients with depression. The use of rTMS in depression is supported by over 20 years of clinical trials. There has been a significant increase in knowledge around the use of rTMS in recent years.

OBJECTIVE

The aim of this paper was to review the use of rTMS in depression to provide an update for rTMS practitioners and clinicians interested in the clinical use of this treatment.

METHODS

A targeted review of the literature around the use of rTMS treatment of depression with a specific focus on studies published in the last 3 years.

RESULTS

High-frequency rTMS applied to the left dorsolateral prefrontal cortex is an effective treatment for acute episodes of major depressive disorder. There are several additional methods of rTMS delivery that are supported by clinical trials and meta-analyses but no substantive evidence that any one approach is any more effective than any other. rTMS is effective in unipolar depression and most likely bipolar depression. rTMS courses may be repeated in the management of depressive relapse but there is less evidence for the use of rTMS in the maintenance phase.

CONCLUSIONS

The science around the use of rTMS is rapidly evolving and there is a considerable need for practitioners to remain abreast of the current state of this literature and its implications for clinical practice. rTMS is an effective antidepressant treatment but its optimal use should be continually informed by knowledge of the state of the art.

Modulation of functional network properties in major depressive disorder following electroconvulsive therapy (ECT): a resting-state EEG analysis

Electroconvulsive therapy (ECT) is a highly effective neuromodulatory intervention for treatment-resistant major depressive disorder (MDD). Presently, however, understanding of its neurophysiological effects remains incomplete. In the present study, we utilised resting-state electroencephalography (RS-EEG) to explore changes in functional connectivity, network topology, and spectral power elicited by an acute open-label course of ECT in a cohort of 23 patients with treatment-resistant MDD. RS-EEG was recorded prior to commencement of ECT and again within 48 h following each patient’s final treatment session. Our results show that ECT was able to enhance connectivity within lower (delta and theta) frequency bands across subnetworks largely confined to fronto-central channels, while, conversely, more widespread subnetworks of reduced connectivity emerged within faster (alpha and beta) bands following treatment. Graph-based topological analyses revealed changes in measures of functional segregation (clustering coefficient), integration (characteristic path length), and small-world architecture following ECT. Finally, post-treatment enhancement of delta and theta spectral power was observed, which showed a positive association with the number of ECT sessions received. Overall, our findings indicate that RS-EEG can provide a sensitive measure of dynamic neural activity following ECT and highlight network-based analyses as a promising avenue for furthering mechanistic understanding of the effects of convulsive therapies.

Effect of Aspirin vs Placebo on the Prevention of Depression in Older People: A Randomized Clinical Trial

IMPORTANCE

Depression is associated with increased inflammation, which may precede its onset, especially in older people. Some preclinical data suggest potential antidepressant effects of aspirin, supported by limited observational data suggesting lower rates of depression in individuals treated with aspirin. There currently appears to be no evidence-based pharmacotherapies for the primary prevention of depression.

OBJECTIVE

To determine whether low-dose aspirin (100 mg) reduces the risk of depression in healthy older adults.

DESIGN, SETTING, AND PARTICIPANTS

This double-blinded, placebo-controlled randomized clinical trial was a substudy of the Aspirin in Reducing Events in the Elderly (ASPREE) trial, which examined if aspirin increased healthy life span, defined as survival free of dementia and disability. The prespecified secondary outcome was depression. Individuals of all races/ethnicities older than 70 years in Australia, as well as white individuals older than 70 years and black and Hispanic individuals older than 65 years in the United States, were included.

INTERVENTIONS

Participants were randomized to aspirin (100 mg daily) or placebo, with a median (interquartile range) follow-up of 4.7 (3.5-5.6) years.

MAIN OUTCOMES AND MEASURES

The primary outcome was a proxy measure of major depressive disorder defined as a score of 8 or more on the Center for Epidemiologic Studies Depression 10-item (CES-D-10) scale.

RESULTS

Of the 19 114 participants enrolled in the trial, 9525 received aspirin and 9589 received a placebo. The mean (SD) age was 75.2 (4.0) years in the aspirin group and 75.1 (4.5) years in the placebo group; 9531 (56.4%) were women. Participants' demographics and clinical characteristics at baseline were similar between groups. A total of 79 886 annual CES-D-10 measurements were taken, with a mean of 4.2 measurements per participant. There were no significant differences at annual visits in the proportions of CES-D-10 scores of 8 or more between the aspirin and placebo groups. The incidence rate of new CES-D-10 scores of 8 or more was 70.4 events per 1000 person-years in the aspirin group and 69.1 in the placebo group (hazard ratio, 1.02 [95% CI, 0.96-1.08]; P = .54).

CONCLUSIONS AND RELEVANCE

Low-dose aspirin did not prevent depression in this large-scale study of otherwise healthy older adults.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01038583.

Magnetic seizure therapy is efficacious and well tolerated for treatment-resistant bipolar depression: an open-label clinical trial

BACKGROUND

Treatment-resistant bipolar depression can be treated effectively using electroconvulsive therapy, but its use is limited because of stigma and cognitive adverse effects. Magnetic seizure therapy is a new convulsive therapy with promising early evidence of antidepressant effects and minimal cognitive adverse effects. However, there are no clinical trials of the efficacy and safety of magnetic seizure therapy for treatment-resistant bipolar depression.

METHODS

Participants with treatment-resistant bipolar depression were treated with magnetic seizure therapy for up to 24 sessions or until remission. Magnetic seizure therapy was applied over the prefrontal cortex at high (100 Hz; n = 8), medium (50 or 60 Hz; n = 9) or low (25 Hz; n = 3) frequency, or over the vertex at high frequency (n = 6). The primary outcome measure was the 24-item Hamilton Rating Scale for Depression. Participants completed a comprehensive battery of neurocognitive tests.

RESULTS

Twenty-six participants completed a minimally adequate trial of magnetic seizure therapy (i.e., ≥ 8 sessions), and 20 completed full treatment per protocol. Participants showed a significant reduction in scores on the Hamilton Rating Scale for Depression. Adequate trial completers had a remission rate of 23.1% and a response rate of 38.5%. Per-protocol completers had a remission rate of 30% and a response rate of 50%. Almost all cognitive measures remained stable, except for significantly worsened recall consistency on the autobiographical memory inventory.

LIMITATIONS

The open-label study design and modest sample size did not allow for comparisons between stimulation parameters.

CONCLUSION

In treatment-resistant bipolar depression, magnetic seizure therapy produced significant improvements in depression symptoms with minimal effects on cognitive performance. These promising results warrant further investigation with larger randomized clinical trials comparing magnetic seizure therapy to electroconvulsive therapy.

CLINICAL TRIAL REGISTRATION

NCT01596608; clinicaltrials.gov

Fixel Based Analysis Reveals Atypical White Matter Micro- and Macrostructure in Adults With Autism Spectrum Disorder: An Investigation of the Role of Biological Sex

Atypical white matter (WM) microstructure is commonly implicated in the neuropathophysiology of autism spectrum disorder (ASD). Fixel based analysis (FBA), at the cutting-edge of diffusion-weighted imaging, can account for crossing WM fibers and can provide indices of both WM micro- and macrostructure. We applied FBA to investigate WM structure between 25 (12 males, 13 females) adults with ASD and 24 (12 males, 12 females) matched controls. As the role of biological sex on the neuropathophysiology of ASD is of increasing interest, this was also explored. There were no significant differences in WM micro- or macrostructure between adults with ASD and matched healthy controls. When data were stratified by sex, females with ASD had reduced fiber density and cross-section (FDC), a combined metric comprised of micro- and macrostructural measures, in the corpus callosum, a finding not detected between the male sub-groups. We conclude that micro- and macrostructural WM aberrations are present in ASD, and may be influenced by biological sex.

Large-scale analysis of interindividual variability in theta-burst stimulation data: Results from the 'Big TMS Data Collaboration'

BACKGROUND

Many studies have attempted to identify the sources of interindividual variability in response to theta-burst stimulation (TBS). However, these studies have been limited by small sample sizes, leading to conflicting results.

OBJECTIVE/HYPOTHESIS

This study brought together over 60 TMS researchers to form the 'Big TMS Data Collaboration', and create the largest known sample of individual participant TBS data to date. The goal was to enable a more comprehensive evaluation of factors driving TBS response variability.

METHODS

118 corresponding authors of TMS studies were emailed and asked to provide deidentified individual TMS data. Mixed-effects regression investigated a range of individual and study level variables for their contribution to iTBS and cTBS response variability.

RESULTS

430 healthy participants' TBS data was pooled across 22 studies (mean age = 41.9; range = 17-82; females = 217). Baseline MEP amplitude, age, target muscle, and time of day significantly predicted iTBS-induced plasticity. Baseline MEP amplitude and timepoint after TBS significantly predicted cTBS-induced plasticity.

CONCLUSIONS

This is the largest known study of interindividual variability in TBS. Our findings indicate that a significant portion of variability can be attributed to the methods used to measure the modulatory effects of TBS. We provide specific methodological recommendations in order to control and mitigate these sources of variability.

Magnetic Seizure Therapy for Suicidality in Treatment-Resistant Depression

Importance

There is an unmet need for effective treatments for suicidality in mental disorders. Magnetic seizure therapy (MST) has been investigated as an alternative to electroconvulsive therapy, a known effective treatment for suicidality, in the management of treatment-resistant major depressive disorder, with promising findings. Yet, there are very limited data on the association of MST with suicidality directly. It is important to explore the potential of MST as a viable treatment alternative to electroconvulsive therapy for suicidality.

Objective

To determine the association of MST with suicidality in patients with treatment-resistant major depressive disorder.

Design, Setting, and Participants

This nonrandomized controlled trial took place at a single tertiary care psychiatric facility in Canada. It followed an open-label study design with consecutive treatment cohorts. Consecutive groupings of 67 patients with treatment-resistant major depressive disorder and with baseline suicidality present were treated for up to 24 treatments. The study was run from February 2012 through June 2019. Patients were followed up for 6 months at the end of the treatment period. This post hoc secondary analysis of the trial was performed from January to November 2019.

Interventions

MST was delivered at 100% stimulator output over the prefrontal cortex with low (25 Hz), moderate (50 or 60 Hz), or high (100 Hz) frequency, for a maximum of 24 sessions.

Main Outcomes and Measures

Remission from suicidality was measured as an end point score of 0 on the Beck Scale for Suicidal Ideation. A linear mixed model was used to assess the trajectory of Beck Scale for Suicidal Ideation scores.

Results

A total of 67 patients (mean [SD] age, 46.3 [13.6] years; 40 women [60.0%]) received a mean (SD) of 19.5 (5.1) MST treatments. The overall number of patients achieving remission was 32 (47.8%). Sixteen patients (55.2%) receiving low-frequency MST achieved remission, as well as 12 patients (54.5%) in the moderate-frequency group, and 4 patients (25.0%) in the high-frequency group. The linear mixed model revealed an association of time with Beck Scale for Suicidal Ideation scores (F8,293.95 = 5.73; P < .001).

Conclusions and Relevance

These findings suggest that MST may be an effective treatment for suicidality, and sensitivity analysis shows this may be particularly so at low and moderate frequencies. Future studies should directly compare MST with electroconvulsive therapy for treating suicidality and should evaluate MST as a treatment for suicidality across mental disorders.

Trial Registration

ClinicalTrials.gov Identifier: NCT01596608.

Transforming treatments for schizophrenia: Virtual reality, brain stimulation and social cognition

Schizophrenia is characterised by delusions, hallucinations, anhedonia and apathy; while impairments in social cognition are often less recognised. Poor social cognition can lead to difficulties in obtaining and maintaining employment, academic progression, interpersonal relationships, and community functioning. Current interventions are highly intensive, require significant resources and have only modest effects on functional outcomes. Virtual reality (VR) and non-invasive brain stimulation (NIBS) may have a role in addressing these limitations. VR allows treatments that are potentially more accessible, less delivery intensive, and have higher ecological validity. While NIBS is able to directly modulate activity in social brain areas in order to promote neuroplasticity, strengthen neural connections and enhance brain function related to social cognitive behaviours. Therefore, the combination of VR and NIBS may allow for more efficient and transferrable interventions than those currently available. This review will explore the potential role of these technologies in the treatment of social cognitive impairment.