Obsessive-compulsive disorder (OCD) is associated with increased electroencephalographic (EEG) delta and theta oscillatory power but reduced delta connectivity

Obsessive-Compulsive Disorder (OCD) is a mental health condition causing significant decline in the quality of life of sufferers and the limited knowledge on the pathophysiology hinders successful treatment. The aim of the current study was to examine electroencephalographic (EEG) findings of OCD to broaden our understanding of the disease. Resting-state eyes-closed EEG data was recorded from 25 individuals with OCD and 27 healthy controls (HC). The 1/f arrhythmic activity was removed prior to computing oscillatory powers of all frequency bands (delta, theta, alpha, beta, gamma). Cluster-based permutation was used for between-group statistical analyses, and comparisons were performed for the 1/f slope and intercept parameters. Functional connectivity (FC) was measured using coherence and debiased weighted phase lag index (d-wPLI), and statistically analyzed using the Network Based Statistic method. Compared to HC, the OCD group showed increased oscillatory power in the delta and theta bands in the fronto-temporal and parietal brain regions. However, there were no significant between-group findings in other bands or 1/f parameters. The coherence measure showed significantly reduced FC in the delta band in OCD compared to HC but the d-wPLI analysis showed no significant differences. OCD is associated with raised oscillatory power in slow frequency bands in the fronto-temporal brain regions, which agrees with the previous literature and therefore is a potential biomarker. Although delta coherence was found to be lower in OCD, due to inconsistencies found between measures and the previous literature, further research is required to ascertain definitive conclusions.

Functional connectivity analysis of the depression connectome provides potential markers and targets for transcranial magnetic stimulation

BACKGROUND

Despite efforts to improve targeting accuracy of the dorsolateral prefrontal cortex (DLPFC) as a repetitive transcranial magnetic stimulation (rTMS) target for Major Depressive Disorder (MDD), the heterogeneity in clinical response remains unexplained.

OBJECTIVE

We sought to compare the patterns of functional connectivity from the DLPFC treatment site in patients with MDD who were TMS responders to those who were TMS non-responders.

METHODS

Baseline anatomical T1 magnetic resonance imaging (MRI), resting-state functional MRI, and diffusion weighted imaging scans were obtained from 37 participants before they underwent a course of rTMS to left Brodmann area 46. A novel machine learning method was utilized to identify brain regions associated with each item of the Beck's Depression Inventory II (BDI-II), and for 26 participants who underwent rTMS treatment over the left Brodmann area 46, identify regions differentiating rTMS responders and non-responders.

RESULTS

Nine parcels of the Human Connectome Project Multimodal Parcellation Atlas matched to at least three items of the Beck's Depression Inventory II (BDI-II) as predictors of response to rTMS, with many in the temporal, parietal and cingulate cortices. Additionally, pre-treatment mapping for 17 items of the BDI-II demonstrated significant variability in symptom to parcel mapping. When parcels associated with symptom presence and symptom resolution were compared, 15 parcels were uniquely associated with resolution (potential targets), and 12 parcels were associated with both symptom presence and resolution (blockers or biomarkers).

CONCLUSIONS

Machine learning approaches show promise for the development of pathoanatomical diagnosis and treatment algorithms for MDD. Prospective studies are required to facilitate clinical translation.

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.

Effects of medial prefrontal transcranial alternating current stimulation on neural activity and connectivity in people with Huntington's disease and neurotypical controls

We investigated the effects of transcranial alternating current stimulation (tACS) targeted to the medial prefrontal cortex (mPFC) on resting electroencephalographic (EEG) indices of oscillatory power, aperiodic exponent and offset, and functional connectivity in 22 late premanifest and early manifest stage individuals with HD and 20 neurotypical controls. Participants underwent three 20-minute sessions of tACS at least 72 hours apart; one session at alpha frequency (either each participant's Individualised Alpha Frequency (IAF), or 10Hz when an IAF was not detected); one session at delta frequency (2Hz); and a session of sham tACS. Session order was randomised and counterbalanced across participants. EEG recordings revealed a reduction of the spectral exponent ('flattening' of the 1/f slope) of the eyes-open aperiodic signal in participants with HD following alpha-tACS, suggestive of an enhancement in excitatory tone. Contrary to expectation, there were no changes in oscillatory power or functional connectivity in response to any of the tACS conditions in the participants with HD. By contrast, alpha-tACS increased delta power in neurotypical controls, who further demonstrated significant increases in theta power and theta functional connectivity in response to delta-tACS. This study contributes to the rapidly growing literature on the potential experimental and therapeutic applications of tACS by examining neurophysiological outcome measures in people with HD as well as neurotypical controls.

Medial prefrontal transcranial alternating current stimulation for apathy in Huntington's disease

We investigated the effects of transcranial alternating current stimulation (tACS) targeted to the bilateral medial prefrontal cortex (mPFC) and administered at either delta or alpha frequencies, on brain activity and apathy in people with Huntington's disease (HD) (n = 17). Given the novelty of the protocol, neurotypical controls (n = 20) were also recruited. All participants underwent three 20-min sessions of tACS; one session at alpha frequency (Individualised Alpha Frequency (IAF), or 10 Hz when an IAF was not detected); one session at delta frequency (2 Hz); and a session of sham tACS. Participants completed the Monetary Incentive Delay (MID) task with simultaneous recording of EEG immediately before and after each tACS condition. The MID task presents participants with cues signalling potential monetary gains or losses that increase activity in key regions of the cortico-basal ganglia-thalamocortical networks, with dysfunction of the latter network being implicated in the pathophysiology of apathy. We used the P300 and Contingent Negative Variation (CNV) event-related potentials elicited during the MID task as markers of mPFC engagement. HD participants' CNV amplitude significantly increased in response to alpha-tACS, but not delta-tACS or sham. Neurotypical controls' P300 and CNV were not modulated by any of the tACS conditions, but they did demonstrate a significant decrease in post-target response times following alpha-tACS. We present this as preliminary evidence of the ability of alpha-tACS to modulate brain activity associated with apathy in HD.

Analgesic efficacy of theta-burst stimulation for postoperative pain

OBJECTIVE

Repetitive transcranial magnetic stimulation (rTMS) may be a relevant method to assist postoperative pain. However, studies to date have only used conventional 10 Hz rTMS and targeted the DLPFC for postoperative pain. A more recent form of rTMS, termed intermittent Theta Burst Stimulation (iTBS), enables to increase cortical excitability in a short period of time. This preliminary double-blind, randomised, sham controlled study was designed to evaluate the efficacy of iTBS in postoperative care across two distinct stimulation targets.

METHODS

A group of 45 patients post laparoscopic surgery were randomised to receive a single session of iTBS over either the dorsolateral prefrontal cortex (DLPFC), primary motor cortex (M1), or Sham stimulation (1:1:1 ratio). Outcome measurements were number of pump attempts, total anaesthetic volume used, and self-rated pain experience, assessed at 1 hour, 6 hours, 24 hours, and 48 hours post stimulation. All randomised patients were analysed (n = 15 in each group).

RESULTS

Compared to Sham stimulation, DLPFC-iTBS reduced pump attempts at 6 (DLPFC = 0.73 ± 0.88, Sham = 2.36 ± 1.65, P = 0.031), 24 (DLPFC = 1.40 ± 1.24, Sham = 5.03 ± 3.87, P = 0.008), and 48 (DLPFC = 1.47 ± 1.41, Sham = 5.87 ± 4.34, P = 0.014) hours post-surgery, whereby M1 stimulation had no effect. No group effect was observed on total anaesthetics, which was mainly provided through the continuous administration of opioids at a set speed for each group. There was also no group or interaction effect on pain ratings. Pump attempts were positively associated with pain ratings in the DLPFC (r = 0.59, P = 0.02) and M1 (r = 0.56, P = 0.03) stimulation.

CONCLUSIONS

Our findings show that iTBS to the DLPFC reduces pump attempts for additional anaesthetics following a laparoscopic surgery. However, reduced pump attempts by DLPFC stimulation did not translate into a significantly smaller volume of total anaesthetic, due to the continuous administration of opioids at a set speed for each group.

SIGNIFICANCE

Our findings therefore provide preliminary evidence for iTBS targeting the DLPFC to be used to improve postoperative pain management.

RELAX part 2: A fully automated EEG data cleaning algorithm that is applicable to Event-Related-Potentials

OBJECTIVE

Electroencephalography (EEG) is often used to examine neural activity time-locked to stimuli presentation, referred to as Event-Related Potentials (ERP). However, EEG is influenced by non-neural artifacts, which can confound ERP comparisons. Artifact cleaning reduces artifacts, but often requires time-consuming manual decisions. Most automated methods filter frequencies <1 Hz out of the data, so are not recommended for ERPs (which contain frequencies <1 Hz). Our aim was to test the RELAX (Reduction of Electroencephalographic Artifacts) pre-processing pipeline for use on ERP data.

METHODS

The cleaning performance of multiple versions of RELAX were compared to four commonly used EEG cleaning pipelines across both artifact cleaning metrics and the amount of variance in ERPs explained by different conditions in a Go-Nogo task. Results RELAX with Multi-channel Wiener Filtering (MWF) and wavelet-enhanced independent component analysis applied to artifacts identified with ICLabel (wICA_ICLabel) cleaned data most effectively and produced amongst the most dependable ERP estimates. RELAX with wICA_ICLabel only or MWF_only may detect effects better for some ERPs.

CONCLUSIONS

RELAX shows high artifact cleaning performance even when data is high-pass filtered at 0.25 Hz (applicable to ERP analyses).

SIGNIFICANCE

RELAX is easy to implement via EEGLAB in MATLAB and freely available on GitHub. Given its performance and objectivity we recommend RELAX to improve artifact cleaning and consistency across ERP research.

Personal and relational changes following deep brain stimulation for treatment-resistant depression: A prospective qualitative study with patients and caregivers

OBJECTIVE

Deep brain stimulation (DBS) and whether it alters patient personality is a much-debated topic within academic literature, yet rarely explored with those directly involved. This study qualitatively examined how DBS for treatment-resistant depression impacts patient personality, self-concept, and relationships from the perspectives of both patients and caregivers.

METHODS

A prospective qualitative design was used. Eleven participants were included (six patients, five caregivers). Patients were enrolled in a clinical trial of DBS of the bed nucleus of the stria terminalis. Semi-structured interviews were conducted with participants before DBS-implantation and 9-months after stimulation-initiation. The 21 interviews were thematically analysed.

RESULTS

Three primary themes were identified: (a) impact of mental illness and treatment on self-concept; (b) device acceptability and usability, and (c) relationships and connection. Severe refractory depression had profoundly impacted who patients were, how they viewed themselves, and the quality and functioning of their relationships. Patients who benefited from DBS felt reconnected with their premorbid self, yet still far from their ideal self. While reductions in depression were broadly beneficial for relationships, the process of adjusting relationship dynamics created new challenges. All patients reported recharging difficulties and challenges adapting to the device.

CONCLUSIONS

Therapeutic response to DBS is a gradual and complex process that involves an evolving self-concept, adjusting relationship dynamics, and growing connection between body and device. This is the first study to provide in-depth insight into the lived experience of DBS for treatment-resistant depression. Patient and caregiver narrative accounts should be routinely collected to guide more person-centred DBS clinical interventions.

Motivationally salient cue processing measured using the monetary incentive delay (MID) task with electroencephalography (EEG): A potential marker of apathy in Huntington's disease

We explored the utility of the Monetary Incentive Delay (MID) task with concurrent encephalography (EEG) as a marker of apathy in people with Huntington's disease (HD) as well as neurotypical controls. Specifically, we assessed between and within-group differences in the amplitude of the P300 and Contingent Negative Variation (CNV) event-related potentials as a function of motivational salience. In contrast to neurotypical controls, HD participants' ERP amplitudes were not differentially modulated by motivationally salient cues (i.e., signalling potential 'gain' or 'loss') compared to 'neutral' cues. Difference waves isolating amplitude specific to the motivationally salient cues were calculated for the P300 and CNV. Only the difference waves for ERPs elicited by 'gain' cues differentiated the groups. The CNV difference wave was also significantly correlated with clinical measures of apathy and processing speed in the HD group. These findings provide initial support for the use of the MID with EEG as a marker of apathy in HD, and its potential as a sensitive outcome measure for novel treatment development.

Digitalized transcranial electrical stimulation: A consensus statement

OBJECTIVE

Although relatively costly and non-scalable, non-invasive neuromodulation interventions are treatment alternatives for neuropsychiatric disorders. The recent developments of highly-deployable transcranial electric stimulation (tES) systems, combined with mobile-Health technologies, could be incorporated in digital trials to overcome methodological barriers and increase equity of access. The study aims are to discuss the implementation of tES digital trials by performing a systematic scoping review and strategic process mapping, evaluate methodological aspects of tES digital trial designs, and provide Delphi-based recommendations for implementing digital trials using tES.

METHODS

We convened 61 highly-productive specialists and contacted 8 tES companies to assess 71 issues related to tES digitalization readiness, and processes, barriers, advantages, and opportunities for implementing tES digital trials. Delphi-based recommendations (>60% agreement) were provided.

RESULTS

The main strengths/opportunities of tES were: (i) non-pharmacological nature (92% of agreement), safety of these techniques (80%), affordability (88%), and potential scalability (78%). As for weaknesses/threats, we listed insufficient supervision (76%) and unclear regulatory status (69%). Many issues related to methodological biases did not reach consensus. Device appraisal showed moderate digitalization readiness, with high safety and potential for trial implementation, but low connectivity.

CONCLUSIONS

Panelists recognized the potential of tES for scalability, generalizability, and leverage of digital trials processes; with no consensus about aspects regarding methodological biases.

SIGNIFICANCE

We further propose and discuss a conceptual framework for exploiting shared aspects between mobile-Health tES technologies with digital trials methodology to drive future efforts for digitizing tES trials.

Cortical excitatory and inhibitory correlates of the fronto-limbic circuit in major depression and differential effects of left frontal brain stimulation in a randomized sham-controlled trial

BACKGROUND

Major depressive disorder (MDD), particularly treatment-resistant ones, is associated with abnormal fronto-limbic glucose metabolism. 10-Hz repetitive transcranial magnetic stimulation (rTMS) over left prefrontal cortex (PFC) is believed to normalize the abnormal metabolism to treat depression. However, the exact molecular mechanisms underlying the mood circuit of depressed brains and whether brain stimulation techniques regulate the underlying molecules remain elusive.

METHODS

Whole-brain glucose metabolism and cortical excitatory and inhibitory markers including P30, N45, P60, N100, and LICI (long-interval cortical inhibition) of TMS-evoked potentials from left DLPFC were measured in 40 subjects with MDD patients. The neurophysiological markers were repeated immediately after 1st session of left PFC rTMS, intermittent theta-burst stimulation (iTBS), and sham (randomly assigned).

RESULTS

Brain glucose metabolism in the limbic structures significantly correlated with left PFC P30 (mainly GABA-A and glutamate receptor mediated) and with LICI (mainly GABA-B receptor mediated inhibition) (FWE-corrected p < 0.001). Correlations between other neurophysiological markers (left PFC N45, P60, and N100) and posterior cingulate cortex, a key region in the default mode network, were also noted. One session of rTMS significantly decreased left PFC P60 (mainly glutamate receptor mediated), while a significant group effect was found for LICI (iTBS < sham).

CONCLUSION

The first study showed that the underlying molecular mechanisms of fronto-limbic circuit of MDD brains involved glutamatergic excitation and GABAergic inhibition at specific time points. In addition, one session of rTMS mainly modulated glutamatergic neurotransmission at left PFC, while the mechanisms of iTBS might involve GABA-B receptor mediated inhibition.

CLINICAL TRIALS REGISTRY NUMBER

UMIN000044951.

Revisiting the effectiveness of repetitive transcranial magnetic stimulation treatment in depression, again

Following on from the publication of the Royal Australian and New Zealand Journal of Psychiatry Mood Disorder Clinical Practice Guidelines (2020) and criticisms of how these aberrantly addressed repetitive transcranial magnetic stimulation treatment of depression, questions have continued to be raised in the journal about this treatment by a small group of authors, whose views we contend do not reflect the broad acceptance of this treatment nationally and internationally. In fact, the evidence supporting the use of repetitive transcranial magnetic stimulation treatment in depression is unambiguous and substantial, consisting of an extensive series of clinical trials supported by multiple meta-analyses, network meta-analysis and umbrella reviews. Importantly, the use of repetitive transcranial magnetic stimulation treatment in depression has also been subject to a series of health economic analyses. These indicate that repetitive transcranial magnetic stimulation is a cost-effective therapy and have been used in some jurisdictions, including Australia, in support of public funding. An argument has been made that offering repetitive transcranial magnetic stimulation treatment may delay potentially effective pharmacotherapy. In fact, there is considerably greater danger of the opposite happening. Repetitive transcranial magnetic stimulation is as, if not more effective, than antidepressant medication after two unsuccessful medication trials and should be a consideration for all patients under these circumstances where available. There is no meaningful ongoing debate about the use of repetitive transcranial magnetic stimulation treatment in depression - it is a safe, effective and cost-effective treatment.

The evidence is in: Repetitive transcranial magnetic stimulation is an effective, safe and well-tolerated treatment for patients with major depressive disorder

Despite more than 25 years of research establishing the antidepressant efficacy of repetitive transcranial magnetic stimulation, there remains uncertainty about the depth and breadth of this evidence base, resulting in confusion as to where repetitive transcranial magnetic stimulation fits in the therapeutic armamentarium in the management of patients with mood disorders. The purpose of this article is to provide a concise description of the evidence base supporting the use of repetitive transcranial magnetic stimulation in the context of the stages of research that typically accompanies the development of evidence for a new therapy. The antidepressant efficacy for the use of repetitive transcranial magnetic stimulation in the treatment of depression has been established through a relatively traditional pathway beginning with small case series, progressing to single-site clinical trials and then to larger multisite randomised double-blind controlled trials. Antidepressant effects have been confirmed in numerous meta-analyses followed more recently by large network meta-analysis and umbrella reviews, with evidence that repetitive transcranial magnetic stimulation may have greater efficacy than alternatives for patients with treatment-resistant depression. Finally, repetitive transcranial magnetic stimulation has been shown to produce meaningful response and remission rates in real-world samples of greater than 5000 patients. The evidence for the antidepressant efficacy of repetitive transcranial magnetic stimulation therapy is overwhelming, and it should be considered a routine part of clinical care wherever available.

Anomalies in global network connectivity associated with early recovery from alcohol dependence: A network transcranial magnetic stimulation and electroencephalography study

Although previous research in alcohol dependent populations identified alterations within local structures of the addiction ‘reward’ circuitry, there is limited research into global features of this network, especially in early recovery. Transcranial magnetic stimulation (TMS) is capable of non‐invasively perturbing the brain network while electroencephalography (EEG) measures the network response. The current study is the first to apply a TMS inhibitory paradigm while utilising network science (graph theory) to quantify network anomalies associated with alcohol dependence. Eleven individuals with alcohol‐dependence (ALD) in early recovery and 16 healthy controls (HC) were administered 75 single pulses and 75 paired‐pulses (inhibitory paradigm) to both the left and right prefrontal cortex (PFC). For each participant, Pearson cross‐correlation was applied to the EEG data and correlation matrices constructed. Global network measures (mean degree, clustering coefficient, local efficiency and global efficiency) were extracted for comparison between groups. Following administration of the inhibitory paired‐pulse TMS to the left PFC, the ALD group exhibited altered mean degree, clustering coefficient, local efficiency and global efficiency compared to HC. Decreases in local efficiency increased the prediction of being in the ALD group, while all network metrics (following paired‐pulse left TMS) were able to adequately discriminate between the groups. In the ALD group, reduced mean degree and global clustering was associated with increased severity of past alcohol use. Our study provides preliminary evidence of altered network topology in patients with alcohol dependence in early recovery. Network anomalies were predictive of high alcohol use and correlated with clinical features of alcohol dependence. Further research using this novel brain mapping technique may identify useful network biomarkers of alcohol dependence and recovery.

Antidepressant treatment outcomes in patients with and without comorbid physical or psychiatric disorders: A systematic review and meta-analysis

BACKGROUND

Many patients with major depressive disorder (MDD) experience substantial impairment despite the availability of efficacious treatments. We performed a systematic review and meta-analysis to compare antidepressant outcomes in MDD with or without physical or psychiatric comorbidities.

METHODS

Pubmed, EMBASE, and PsycInfo were searched up to May 14th, 2020 using keywords including MDD, antidepressant, medication, and comorbid. 1915 studies were reviewed. Studies that performed a direct and quantitative comparison of antidepressant effect in patients with MDD with or without comorbidities were included. Study characteristics and primary outcomes were extracted. Continuous and dichotomous variables were considered using standardized mean difference (SMD). Heterogeneity was measured using χ² and I² tests. Risk of bias was assessed using Cochrane Risk of Bias tool and NIH Quality Assessment Tool.

RESULTS

26 studies met selection criteria. Studies of physical (6 studies; I² = 57.69%, p = 0.04) and psychiatric comorbidities (20 studies; I² = 75.75%, p < 0.001) were heterogeneous. When compared to patients with MDD without comorbidities, those with physical (SMD = -0.19, 95% CI: -0.30 to -0.08, p = 0.001; 1910 and 2905 patients with or without comorbidities) or psychiatric comorbidities (SMD = -0.20, 95% CI: -0.31 to -0.095, p < 0.001; 4308 and 6867 patients with or without comorbidities) had worse antidepressant outcomes.

LIMITATIONS

Our limitations included aggregating the comorbidities into physical and psychiatric comorbidities and the high heterogeneity of the studies.

CONCLUSIONS

Our review provides updated evidence demonstrating that patients with MDD and physical or psychiatric comorbidities experience worse antidepressant outcomes.

Understanding the Barriers and Facilitators to Employment for People with Bipolar Disorder

People with Bipolar Disorder (BD) consistently report a desire for employment; however, this is not reflected in employment figures. Individuals' perceptions of barriers to employment, along with endorsement of facilitators to employment remain under-investigated. We aimed to address this limitation by: (i) first examining differences in employed versus unemployed individuals (demographic, clinical, functioning); then (ii) identifying barriers and/or facilitators to employment, perception of same, and subsequent impact on employment. We assessed demographics, functioning, and illness-related characteristics in 35 participants with BD (19 employed, 16 unemployed). Participants were asked to indicate perception of common barriers and facilitators to employment. Groups did not differ regarding demographic or clinical variables. High levels of absenteeism, termination of last role and commonly perceived barriers were attributed to mental ill-health. 93.3% of unemployed participants reportedly desired employment, and more perceived barriers were observed in the unemployed group. Identified facilitators included increased support and flexible work strategies. A comprehensive understanding of perceptions of limiting and helpful factors related to employment for people with BD was obtained. These findings have implications for service provision, encouraging targeted discussion, and tailored treatment approaches to individual's unique perceptions of factors related to employment.

Investigating Neurophysiological Markers of Symptom Severity in Alzheimer's Disease

BACKGROUND

Alzheimer's disease (AD) is characterized by a progressive decline in cognitive functioning for which there is a stark lack of effective treatments. Investigating the neurophysiological markers of symptom severity in AD may aid in the identification of alternative treatment targets.

OBJECTIVE

In the current study, we used a multimodal approach to investigate the association between functional connectivity (specifically between scalp electrodes placed over frontal and parietal regions) and symptom severity in AD, and to explore the relationship between connectivity and cortical excitability.

METHODS

40 people with AD (25 mild severity, 15 moderate severity) underwent neurobiological assessment (resting state electroencephalography (EEG) and prefrontal transcranial magnetic stimulation (TMS) with EEG) and cognitive assessment. Neurobiological outcomes were resting state functional connectivity and TMS-evoked potentials. Cognitive outcomes were scores on the Alzheimer's Disease Assessment Scale-Cognitive Subscale, Mini-Mental Status Examination, and a measure of episodic verbal learning.

RESULTS

Greater contralateral functional theta connectivity between frontal scalp electrodes and parietal scalp electrodes was associated with poorer cognitive performance. In addition, significant correlations were seen between the contralateral theta connectivity and the N100 and P60 TMS-evoked potentials measured from electrodes over the left dorsolateral prefrontal cortex.

CONCLUSION

Together these findings provide initial support for the use of a multimodal neurophysiological approaches to investigate potential therapeutic targets in AD. Suggestions for future research are discussed.

EEG-connectivity: A fundamental guide and checklist for optimal study design and evaluation

Brain connectivity can be estimated through many analyses applied to electroencephalographic (EEG) data. However, substantial heterogeneity in the implementation of connectivity methods exist. Heterogeneity in conceptualization of connectivity measures, data collection, or data pre-processing may be associated with variability in robustness of measurement. While it is difficult to compare the results of studies using different EEG connectivity measures, standardization of processing and reporting may facilitate the task. We discuss how factors such as referencing, epoch length and number, controls for volume conduction, artefact removal, and statistical control of multiple comparisons influence the EEG connectivity estimate for connectivity measures, and what can be done to control for potential confounds associated with these factors. Based on the results reported in previous literature, this article presents recommendations and a novel checklist developed for quality assessment of EEG connectivity studies. This checklist and its recommendations are made in an effort to draw attention to factors that may influence connectivity estimates and factors that need to be improved in future research. Standardization of procedures and reporting in EEG connectivity may lead to EEG connectivity studies to be made more synthesisable and comparable despite variations in the methodology underlying connectivity estimates.

Feasibility of using discrete Brain Computer Interface for people with Multiple Sclerosis

AIM

Brain-Computer Interfaces (BCIs) hold promise to provide people with partial or complete paralysis, the ability to control assistive technology. This study reports offline classification of imagined and executed movements of the upper and lower limb in one participant with multiple sclerosis and people with no limb function deficits.

METHODS

We collected neural signals using electroencephalography (EEG) while participants performed executed and imagined motor tasks as directed by prompts shown on a screen.

RESULTS

Participants with no limb function attained >70% decoding accuracy on their best-imagined task compared to rest and on at-least one task comparison. The participant with multiple sclerosis also achieved accuracies within the range of participants with no limb function loss.Clinical Relevance - While only one case study is provided it was promising that the participant with MS was able to achieve comparable classification to that of the seven healthy controls. Further studies are needed to assess whether people suffering from MS may be able to use a BCI to improve their quality of life.

Personalising transcranial magnetic stimulation for depression using neuroimaging: A systematic review

OBJECTIVES

Transcranial magnetic stimulation (TMS) is a well-established and effective treatment for depression, though response rates are suboptimal. Personalising TMS for depression with neuroimaging can take into account inter-individual differences in anatomical and electrophysiological characteristics; and thereby provide a potentially more efficacious form of treatment. The current systematic review aimed to critically appraise the literature relating to personalising TMS for depression with neuroimaging.

METHODS

PubMed, PsycINFO and Embase databases were used to identify relevant literature published up to November 2020.

RESULTS

A total of 37 studies were included in the review. Across these studies, a total of 1451 patients with depression received TMS that was personalised using neuroimaging. The majority of the studies used structural or functional neuroimaging to personalise treatment target (n = 30), primarily through neuronavigation methodologies. Fewer studies used electroencephalography to personalise treatment frequency or stimulus timing (n = 7). Only 6 studies directly compared neuroimaging-personalised TMS to standard TMS.

CONCLUSIONS

The findings from this review suggest that personalising TMS with neuroimaging may be more effective in the treatment of depression compared to standard TMS. Further research is required to directly compare neuroimaging-personalised TMS with standard TMS, and to identify the optimal parameters for treatment personalisation.

Continuation Magnetic Seizure Therapy for Treatment-Resistant Unipolar or Bipolar Depression

Objective: Electroconvulsive therapy (ECT) is highly effective for treatment-resistant depression (TRD) but may be associated with adverse cognitive effects. Magnetic seizure therapy (MST) is a promising alternative convulsive treatment with a safer cognitive profile. Although there is emerging evidence for the efficacy of MST for TRD as an acute treatment, there are no published studies of continuation MST for the prevention of relapse. Methods: Patients with TRD with a DSM-IV diagnosis of major depressive disorder or bipolar disorder who met response criteria after acute MST were offered continuation MST in a prospective, open-label trial between February 2012 and June 2019. They received 12 continuation MST sessions with decreasing frequency over the course of 6 months, with additional booster sessions if their depression symptoms started to worsen. The primary outcome was relapse of depression or psychiatric hospitalization. Secondary outcomes included relapse of suicidal ideation and neurocognitive outcomes. Results: Thirty participants completing at least one assessment during continuation MST were included in the analysis; 10 (33.3%) relapsed, with no significant differences in survival distributions between unipolar and bipolar groups (χ² = 0.3, P = .58). Mean (SD) survival time was 18.6 (1.6) weeks. All 17 participants who achieved resolution of baseline suicidality after acute MST remained free of suicidality during the continuation phase. Except for improvement in verbal fluency, neurocognitive test scores did not change during continuation MST. Conclusions: During 6 months of continuation MST, two-thirds of participants sustained improvements in depressive symptoms without any adverse cognitive effects. Future studies of continuation MST are warranted, particularly in comparison to ECT. Trial Registration: ClinicalTrials.gov identifier: NCT01596608.