Excessive left anterior hippocampal and caudate activation in schizophrenia underlie cognitive underperformance in a virtual navigation task.

We used a virtual navigation paradigm in a city environment to assess neuroanatomical correlates of cognitive deficits in schizophrenia spectrum disorders (SSD). We studied a total of N = 36 subjects: 18 with SSD and 18 matched unaffected controls. Participants completed 10 rapid, single-trial navigation tasks within the virtual city while undergoing functional magnetic resonance imaging (fMRI). All trials tested ability to find different targets seen earlier, during the passive viewing of a path around different city blocks. SSD patients had difficulty finding previously-encountered targets, were less likely to find novel shortcuts to targets, and more likely to attempt retracing of the path observed during passive viewing. Based on a priori region-of-interest analyses, SSD participants had hyperactivation of the left hippocampus when passively viewing turns, hyperactivation of the left caudate when finding targets, and hypoactivation of a focal area of the dorsolateral prefrontal cortex when targets were initially shown during passive viewing. We propose that these brain-behaviour relations may bias or reinforce stimulus-response navigation approaches in SSD and underlie impaired performance when allocentric spatial memory is required, such as when forming efficient shortcuts. This pattern may extend to more general cognitive impairments in SSD that could be used to design remediation strategies.

EF1α-associated protein complexes affect dendritic spine plasticity by regulating microglial phagocytosis in Fmr1 knock-out mice.

Fragile X syndrome (FXS) is the most common inherited cause of intellectual disability. There is no specific treatment for FXS due to the lack of therapeutic targets. We report here that Elongation Factor 1α (EF1α) forms a complex with two other proteins: Tripartite motif-containing protein 3 (TRIM3) and Murine double minute (Mdm2). Both EF1α-Mdm2 and EF1α-TRIM3 protein complexes are increased in the brain of Fmr1 knockout mice as a result of FMRP deficiency, which releases the normal translational suppression of EF1α mRNA and increases EF1α protein levels. Increased EF1α-Mdm2 complex decreases PSD-95 ubiquitination (Ub-PSD-95) and Ub-PSD-95-C1q interaction. The elevated level of TRIM3-EF1α complex is associated with decreased TRIM3-Complement Component 3 (C3) complex that inhibits the activation of C3. Both protein complexes thereby contribute to a reduction in microglia-mediated phagocytosis and dendritic spine pruning. Finally, we created a peptide that disrupts both protein complexes and restores dendritic spine plasticity and behavioural deficits in Fmr1 knockout mice. The EF1α-Mdm2 and EF1α-TRIM3 complexes could thus be new therapeutic targets for FXS.

Small-molecule targeting AMPA-mediated excitotoxicity has therapeutic effects in mouse models for multiple sclerosis.

While most research and treatments for multiple sclerosis (MS) focus on autoimmune reactions causing demyelination, it is possible that neurodegeneration precedes the autoimmune response. Hence, glutamate receptor antagonists preventing excitotoxicity showed promise in MS animal models, though blocking glutamate signaling prevents critical neuronal functions. This study reports the discovery of a small molecule that prevents AMPA-mediated excitotoxicity by targeting an allosteric binding site. A machine learning approach was used to screen for small molecules targeting the AMPA receptor GluA2 subunit. The lead candidate has potent effects in restoring neurological function and myelination while reducing the immune response in experimental autoimmune encephalitis and cuprizone MS mouse models without affecting basal neurotransmission or learning and memory. These findings facilitate development of a treatment for MS with a different mechanism of action than current immune modulatory drugs and avoids important off-target effects of glutamate receptor antagonists. This class of MS therapeutics could be useful as an alternative or complementary treatment to existing therapies.

Care Pathways and Initial Engagement in Early Psychosis Intervention Services Among Youths and Young Adults.

Importance: Broad efforts to improve access to early psychosis intervention (EPI) services may not address health disparities in pathways to care and initial engagement in treatment. Objective: To understand factors associated with referral from acute hospital-based settings and initial engagement in EPI services. Design, Setting, and Participants: This retrospective cohort study used electronic medical record data from all patients aged 16 to 29 years who were referred to a large EPI program between January 2018 and December 2019. Statistical analysis was performed from March 2022 to February 2023. Exposures: Patients self-reported demographic information in a structured questionnaire. The main outcome for the first research question (referral source) was an exposure for the second research question (initial attendance). Main Outcomes and Measures: Rate of EPI referral from acute pathways compared with other referral sources, and rate of attendance at the consultation appointment. Results: The final study population included 999 unique patient referrals. At referral, patients were a mean (SD) age of 22.5 (3.5) years; 654 (65.5%) identified as male, 323 (32.3%) female, and 22 (2.2%) transgender, 2-spirit, nonbinary, do not know, or prefer not to answer; 199 (19.9%) identified as Asian, 176 (17.6%) Black, 384 (38.4%) White, and 167 (16.7%) other racial or ethnic groups, do not know, or prefer not to answer. Participants more likely to be referred to EPI services from inpatient units included those who were older (relative risk ratio [RRR], 1.10; 95% CI, 1.05-1.15) and those who identified as Black (RRR, 2.11; 95% CI, 1.38-3.22) or belonging to other minoritized racial or ethnic groups (RRR, 1.79; 95% CI, 1.14-2.79) compared with White participants. Older patients (RRR, 1.16; 95% CI, 1.11-1.22) and those who identified as Black (RRR, 1.67; 95% CI, 1.04-2.70) or belonging to other minoritized racial or ethnic groups (RRR, 2.11; 95% CI, 1.33-3.36) were more likely to be referred from the emergency department (ED) compared with White participants, whereas participants who identified as female (RRR, 0.51 95% CI, 0.34-.74) had a lower risk of ED referral compared with male participants. Being older (odds ratio [OR], 0.95; 95% CI, 0.90-1.00) and referred from the ED (OR, 0.40; 95% CI, 0.27-0.58) were associated with decreased odds of attendance at the consultation appointment. Conclusions and relevance: In this cohort study of patients referred to EPI services, disparities existed in referral pathways and initial engagement in services. Improving entry into EPI services may help facilitate a key step on the path to recovery among youths and young adults with psychosis.

Evaluating the effect of electroconvulsive therapy (ECT) on post-traumatic stress disorder (PTSD): A systematic review and meta-analysis of five studies.

ECT has been proposed as a potential treatment for PTSD. There is a small number of clinical studies to date, but no quantitative review of the efficacy has been conducted. We performed a systematic review and meta-analysis to evaluate the effect of ECT in reducing PTSD symptoms. We followed the PICO and the PRISMA guidelines and searched PubMed, MEDLINE (Ovid), EMBASE (Ovid), Web of Science, and the Cochrane Central Register of Controlled Trials (PROSPERO No: CRD42022356780). A random effects model meta-analysis was conducted with the pooled standard mean difference, applying Hedge's adjustment for small sample sizes. Five within-subject studies met the inclusion criteria, containing 110 patients with PTSD symptoms receiving ECT (mean age 44.13 ± 15.35; 43.4% female). ECT had a small but significant pooled effect on reducing PTSD symptoms (Hedges' g = -0.374), reducing intrusion (Hedges' g = -0.330), avoidance (Hedges' g = -0.215) and hyperarousal (Hedges' g = -0.171) symptoms. Limitations include the small number of studies and subjects and the heterogeneity of study designs. These results provide preliminary quantitative support for the use of ECT in the treatment of PTSD.

Serum amyloid P component (SAP) modulates antidepressant effects through promoting membrane insertion of the serotonin transporter.

Serum amyloid P component (SAP) is a universal constituent of human amyloid deposits including those in Alzheimer's disease. SAP has been observed to be elevated in patients with depression, and higher SAP levels are associated with better response to the antidepressant escitalopram. The mechanisms underlying these clinical observations remain unclear. We examined the effect of SAP on serotonin transporter (SERT) expression and localization using Western blot, confocal microscopy, and positron emission tomography with the radioligand [11C]DASB. We also investigated the effect of SAP on treatment response to escitalopram in mice with the forced swim test (FST), a classical behaviour paradigm to assess antidepressant effects. SAP reduced [11C]DASB binding as an index of SERT levels, consistent with Western blots showing decreased total SAP protein because of increased protein degradation. In conjunction with the global decrease in SERT levels, SAP also promotes VAMP-2 mediated SERT membrane insertion. SAP levels are correlated with behavioural despair and SSRI treatment response in mice with FST. In MDD patients, the SAP and membrane SERT levels are correlated with response to SSRI treatment. SAP has complex effects on SERT levels and localization, thereby modulating the effect of SSRIs, which could partially explain clinical variability in antidepressant treatment response. These results add to our understanding of the mechanism for antidepressant drug action, and with further work could be of clinical utility.

Development of a novel peptide to prevent entry of SARS-CoV-2 into lung and olfactory bulb cells of hACE2 expressing mice.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel coronavirus that has caused a global pandemic Coronavirus Disease 2019 (COVID-19). Currently, there are no effective treatments specifically for COVID-19 infection. The initial step in SARS-CoV-2 infection is attachment to the angiotensin-converting enzyme 2 (ACE2) on the cell surface. We have developed a protein peptide that effectively disrupts the binding between the SARS-CoV-2 spike protein and ACE2. When delivered by nasal spray, our peptide prevents SARS-CoV-2 spike protein from entering lung and olfactory bulb cells of mice expressing human ACE2. Our peptide represents a potential novel treatment and prophylaxis against COVID-19.

The GR-FKBP51 interaction modulates fear memory but not spatial or recognition memory.

The glucocorticoid receptor (GR) forms a protein complex with FKBP51 that is increased in post-traumatic stress disorder (PTSD) and by fear conditioned learning. Disrupting the GR-FKBP51 complex with a synthetic peptide can block the storage or retrieval of fear conditioned memories, which could be a novel approach to the alleviate fear associated memory in PTSD. However, a potential unacceptable side effect could be the impairment of other types of memory. Thus, we investigated the effect of disrupting the GR-FKBP51 complex on recognition memory using the novel object and displaced object recognition tasks, spatial memory in the Morris water maze, and on social interaction in Crawley's three-chamber social interaction test. We did not observe adverse effects on these other types of memory and conclude that the GR-FKBP51 interaction remains a promising target for treating psychiatric disorders characterized by unwanted aversive memories such as in PTSD.

The D2R-DISC1 protein complex and associated proteins are altered in schizophrenia and normalized with antipsychotic treatment.

BACKGROUND: For decades, the dopamine D2 receptor (D2R) has been known as the main target of antipsychotic medications, but the mechanism for antipsychotic effects beyond this pharmacological target remains unclear. Disrupted-in-schizophrenia 1 (DISC1) is a gene implicated in the etiology of schizophrenia, and we have found elevated levels of the D2R-DISC1 complex in the postmortem brain tissue of patients with schizophrenia. METHODS: We used coimmunoprecipitation to measure D2R-DISC1 complex levels in peripheral blood samples from patients with schizophrenia and unaffected controls in 3 cohorts (including males and females) from different hospitals. We also used label-free mass spectrometry to conduct proteomic analysis of these samples. RESULTS: Levels of the D2R-DISC1 complex were elevated in the peripheral blood samples of patients with schizophrenia from 3 independent cohorts, and were normalized with antipsychotic treatment. Proteomic analysis of the blood samples from patients with high D2R-DISC1 complex levels that were normalized with antipsychotic treatment revealed a number of altered proteins and pathways associated with D2R, DISC1 and the D2R-DISC1 complex. We identified additional proteins and pathways that were associated with antipsychotic treatment in schizophrenia, and that may also be novel targets for schizophrenia treatment. LIMITATIONS: Sample sizes were relatively small, but were sufficient to detect associations between D2R-DISC1 levels, schizophrenia and treatment response. The relevance of leukocyte changes to the symptoms of schizophrenia is unknown. The coimmunoprecipitation lanes included several nonspecific bands. CONCLUSION: Levels of the D2R-DISC1 complex were elevated in patients with schizophrenia and reduced with antipsychotic treatment. This finding reinforces the independent role of each protein in schizophrenia. Our results enhanced our understanding of the molecular pathways involved in schizophrenia and in antipsychotic medications, and identified novel potential molecular targets for treating schizophrenia.

Serum amyloid P component level is associated with clinical response to escitalopram treatment in patients with major depressive disorder.

Serum amyloid P component (SAP) is a universal constituent of human amyloid deposits, which has been implicated in Alzheimer's disease and major depressive disorder (MDD). However, the relationship between SAP level and depression severity remains obscure. The aims of this study were to investigate how SAP is involved in depression and to explore the association between SAP level and antidepressant treatment response. Patients with MDD (n = 85) who received escitalopram monotherapy for 8-12 weeks were selected from a multicenter open-label randomized clinical trial. The same number of healthy controls was recruited. Depression severity was measured according to the Hamilton Depression Rating Scale (HAMD-17) at baseline and weeks 4, 8, and 12. The plasma levels of SAP were measured at baseline, week 2 and week 12. As a result, baseline levels of SAP were significantly higher in depressed patients than in control subjects (p < 0.001). SAP levels at baseline were negatively associated with depression severity after escitalopram treatment (p < 0.05), and the changes in SAP levels from baseline to week 12 were highly correlated with the severity of depressive symptoms based on the HAMD-17 score (p < 0.05). Interestingly, treatment with escitalopram significantly decreased the plasma levels of SAP in females, but not in males. Altogether, our results suggest that SAP not only involved in the pathobiology of depression but also mediates the action of antidepressant medications.

Emotional memory for facial expressions in schizophrenia spectrum disorders: The role of encoding method.

Memory is better for emotional rather than neutral events or materials (emotional enhancement of memory; EEM). Evidence suggests that this memory benefit remains intact in schizophrenia, but conflicting findings present the need for further research to understand how and when this process occurs. Here, we examine whether different encoding methods for learning emotional faces may result in different EEM patterns in those with schizophrenia spectrum disorders (SSD). A patient group (n = 28) and healthy comparisons (n = 29) encoded faces in two conditions that manipulated attentional focus to promote direct (emotion judgements) or indirect (sex discrimination) processing of emotional content. Based on literature in schizophrenia showing selective emotion perception deficits on tasks of direct processing but relatively intact emotion perception on indirect processing tasks, we hypothesized that patients would show greater EEM effects when faces were encoded indirectly. This hypothesis was not supported, and the patient group instead showed a similar intact EEM for angry and fearful faces to healthy comparisons in both encoding conditions. Further, using the Remember/Know paradigm, we demonstrated that the EEM in SSD appears selective to recollection-based memory, which helps to explain inconsistencies in past literature that has not differentiated between recognition domains. These findings have important implications for improving emotional memory and functional outcomes in SSD; future research should establish how the EEM for facial expressions may relate to social functioning.

Sex Differences in Dopamine Receptor Signaling in Fmr1 Knockout Mice: A Pilot Study.

Fragile X syndrome (FXS) is an X-chromosome-linked dominant genetic disorder that causes a variable degree of cognitive dysfunction and developmental disability. Current treatment is symptomatic and no existing medications target the specific cause of FXS. As with other X-linked disorders, FXS manifests differently in males and females, including abnormalities in the dopamine system that are also seen in Fmr1-knockout (KO) mice. We investigated sex differences in dopamine signaling in Fmr1-KO mice in response to L-stepholidine, a dopamine D1 receptor agonist and D2 receptor antagonist. We found significant sex differences in basal levels of phosphorylated protein kinase A (p-PKA) and glycogen synthase kinase (GSK)-3ß in wild type mice that were absent in Fmr1-KO mice. In wild-type mice, L-stepholidine increased p-PKA in males but not female mice, decreased p-GSK-3 in female mice and increased p-GSK-3 in male mice. Conversely, in Fmr1-KO mice, L-stepholidine increased p-PKA and p-GSK-3ß in females, and decreased p-PKA and p-GSK-3ß in males.

Disrupting the α7nAChR-NR2A protein complex exerts antidepressant-like effects.

Major depressive disorder (MDD) is associated with significant morbidity and mortality. Most antidepressant medications target the serotonin and norepinephrine transporters, but a significant minority of patients do not respond to treatment and novel therapeutic targets are needed. We previously identified a protein complex composed of the α7 nicotinic acetylcholine receptor (nAChR) and NMDA glutamate receptors (NMDARs), through which α7nAChR upregulates NMDAR function. Disruption of the α7nAChR-NMDAR complex with an interfering peptide blocked α7nAChR-mediated upregulation of NMDAR function and cue-induced reinstatement of nicotine seeking in rat models of relapse. Here we report that disrupting the α7nAChR-NMDAR complex with the interfering peptide also has antidepressant-like effects in the forced swim test (FST), a common rat behaviour screening test for antidepressant effects. Furthermore, the interfering peptide significantly increases extracellular signal-regulated kinase (ERK) activity in the animals subjected to the FST. Our results provide a novel potential therapeutic target for the development of new antidepressant medications.

The Impact of COVID-19 on Psychiatric Emergency and Inpatient Services in the First Month of the Pandemic in a Large Urban Mental Health Hospital in Ontario, Canada.

The World Health Organization characterized COVID-19 (coronavirus disease 2019) as a pandemic on March 11, 2020 (WHO). Within a couple of days, all Canadian provinces announced the implementation of social distancing measures. We evaluated the immediate effect of COVID-19 on psychiatric emergency and inpatient services in Canada's largest psychiatric hospital in the first month of the pandemic. We extracted data from the electronic medical records of the Center for Addiction and Mental Health in Toronto, Canada. We compared emergency department visits, inpatient occupancy rates, and length of stay in March 2019 and March 2020, and during the first and second half of March 2020. There was a decrease in the number of emergency department visits and inpatient occupancy rates in March 2020 compared to March 2019. There was also a significant decrease in the number of emergency department visits and inpatient occupancy rates in the second half of March 2020 compared to the first half. Our findings suggest that the pandemic was followed by a rapid decrease in the usage of psychiatric emergency and inpatient services in a large mental health hospital. Future studies will need to assess whether this decrease will be followed by a return to baseline or an increase in need for these services.

Electroconvulsive therapy with a memory reactivation intervention for post-traumatic stress disorder: A randomized controlled trial.

BACKGROUND: Post-traumatic Stress Disorder (PTSD) often does not respond to available treatments. Memories are vulnerable to disruption during reconsolidation, and electroconvulsive therapy (ECT) has amnestic effects OBJECTIVE/HYPOTHESIS: To test the use of ECT to disrupt the reconsolidation of traumatic memories as a potential treatment for PTSD METHODS: Participants were adults from the civilian population and were referred for ECT treatment for severe depression with comorbid PTSD symptoms. Twenty-eight participants were randomly assigned to reactivation of a traumatic or non-traumatic memory using audio script driven imagery prior to each ECT treatment. Primary outcomes were change in scores on the Modified PTSD Symptom Scale - Self Report (MPSS-SR) and the Clinician-Administered PTSD Scale for DSM-5 (CAPS-5). Secondary outcomes included a comparison of the change in heart rate while listening to the script RESULTS: Twenty-five female patients who completed a post-ECT assessment were included in the analysis. No significant group differences were found in the MPSS-SR or CAPS-5 scores from pre-ECT to post-ECT or 3-month follow-ups. However, both groups improved at post-ECT and 3-month follow up. Partial eta squared estimates of effect size showed large effect sizes for all outcomes (η2 > 0.13). Changes in heart rate were not significantly different between groups or over time CONCLUSIONS: ECT paired with pre-treatment traumatic memory reactivation was not more effective for treating PTSD symptoms than ECT with non-traumatic memory reactivation. While our primary hypothesis was not supported, our data provides further support for the efficacy of ECT for improving symptoms of PTSD with comorbid depression. ClinicalTrials.gov. https://clinicaltrials.gov/ct2/show/NCT04027452. IDENTIFIER: NCT04027452.

ED to EPI: protocol for a pragmatic randomised controlled trial of an SMS (text) messaging intervention to improve the transition from the emergency department to early psychosis intervention for young people with psychosis.

INTRODUCTION: While nearly half of all new psychotic disorders are diagnosed in the emergency department (ED), most young people who present to the ED with psychosis do not receive timely follow-up with a psychiatrist, and even fewer with evidence-based early psychosis intervention (EPI) services. We aim to test an intervention delivered using short message service (SMS), a low-cost, low-complexity, youth-friendly approach, to improve transitions from the ED to EPI services. METHODS AND ANALYSIS: This is a protocol for a pragmatic randomised, single blind, controlled trial with accompanying economic and qualitative evaluations conducted at the Centre for Addiction and Mental Health (CAMH) in Toronto, Canada. A consecutive series of 186 participants aged 16-29 referred by the ED to CAMH's EPI programme will be recruited for a trial of a two-way intervention involving reminders, psychoeducation and check-ins delivered via SMS. The primary outcome will be attendance at the first consultation appointment within 30 days of study enrolment assessed through chart reviews in the electronic health record. We will also extract routine clinical measures, including the Brief Psychiatric Rating Scale, Clinical Global Impression and Service Engagement Scale, and link with provincial health administrative data to examine system-level outcomes, including ED visits and psychiatric hospitalisations, 6 months and up to 2 years after baseline. We will perform a cost-effectiveness analysis of the primary study outcome and costs incurred, calculating an incremental cost effectiveness ratio. Web-based surveys and qualitative interviews will explore intervention user experience. Patients and families with lived experience will be engaged in all aspects of the project. ETHICS AND DISSEMINATION: Research Ethics Board approval has been obtained. Findings will be reported in scientific journal articles and shared with key stakeholders including youth, family members, knowledge users and decision makers. TRIAL REGISTRATION NUMBER: NCT04298450.

Bioactive Chemical Composition of Cannabis Extracts and Cannabinoid Receptors.

Cannabis is widely used as a therapeutic drug, especially by patients suffering from psychiatric and neurodegenerative diseases. However, the complex interplay between phytocannabinoids and their targets in the human receptome remains largely a mystery, and there have been few investigations into the relationship between the chemical composition of medical cannabis and the corresponding biological activity. In this study, we investigated 59 cannabis samples used by patients for medical reasons. The samples were subjected to extraction (microwave and supercritical carbon dioxide) and chemical analyses, and the resulting extracts were assayed in vitro using the CB1 and CB2 receptors. Using a partial least squares regression analysis, the chemical compositions of the extracts were then correlated to their corresponding cannabinoid receptor activities, thus generating predictive models that describe the receptor potency as a function of major phytocannabinoid content. Using the current dataset, meaningful models for CB1 and CB2 receptor agonism were obtained, and these reveal the insignificant relationships between the major phytocannabinoid content and receptor affinity for CB1 but good correlations between the two at CB2 receptors. These results also explain the anomalies between the receptor activities of pure phytocannabinoids and cannabis extracts. Furthermore, the models for CB1 and CB2 agonism in cannabis extracts predict the cannabinoid receptor activities of individual phytocannabinoids with reasonable accuracy. Here for the first time, we disclose a method to predict the relationship between the chemical composition, including phytocannabinoids, of cannabis extracts and cannabinoid receptor responses.

The DISC1 R264Q variant increases affinity for the dopamine D2 receptor and increases GSK3 activity.

The Disrupted in schizophrenia 1 (DISC1) gene encodes a scaffolding protein that is involved in many neural functions such as neurogenesis, neural differentiation, embryonic neuron migration and neurotransmitter signalling. DISC1 was originally implicated in schizophrenia in a single family with a drastic mutation, a chromosomal translocation severing the mid-point of the gene (aa 598). Some common DISC1 variants have also been associated with schizophrenia in the general population, but those located far from the chromosomal translocation breakpoint likely have a different functional impact. We previously reported that DISC1 forms a protein complex with dopamine D2 receptor (D2R), the main target for antipsychotic medications. The D2R-DISC1 complex is elevated in brain tissue from schizophrenia patients and facilitates glycogen synthase kinase (GSK)-3 signaling. The DISC1 R264Q variant is located within the region that binds the D2R, and we found that this polymorphism increases the affinity of DISC1 for the D2R and promotes GSK3 activity. Our results suggest a possible mechanism by which this common polymorphism could affect aspects of brain function that are relevant to psychosis and schizophrenia. This provides additional insight into molecular mechanisms underlying schizophrenia that could be exploited in the development of novel pharmacological treatments.

Magnetic seizure therapy (MST) for major depressive disorder.

Electroconvulsive therapy (ECT) is effective for major depressive disorder (MDD) but its effects on memory limit its widespread use. Magnetic seizure therapy (MST) is a potential alternative to ECT that may not adversely affect memory. In the current trial, consecutive patients with MDD consented to receive MST applied over the prefrontal cortex according to an open-label protocol. Depressive symptoms and cognition were assessed prior to, during and at the end of treatment. Patients were treated two to three times per week with high-frequency MST (i.e., 100 Hz) (N = 24), medium frequency MST (i.e., 60 or 50 Hz) (N = 26), or low-frequency MST (i.e., 25 Hz MST) (N = 36) using 100% stimulator output. One hundred and forty patients were screened; 86 patients with MDD received a minimum of eight treatments and were deemed to have an adequate course of MST; and 47 completed the trial per protocol, either achieving remission (i.e., 24-item Hamilton Rating Scale for Depression score <10 and a relative reduction of >60% at two consecutive assessments; n = 17) or received a maximum of 24 sessions (n = 30). High-frequency (100 Hz) MST produced the highest remission rate (33.3%). Performance on most cognitive measures remained stable, with the exception of significantly worsened recall consistency of autobiographical information and significantly improved brief visuospatial memory task performance. Under open conditions, MST led to clinically meaningful reduction in depressive symptoms in patients with MDD and produced minimal cognitive impairment. Future studies should compare MST and ECT under double-blind randomized condition.