Age-Related Repetitive Transcranial Magnetic Stimulation Effects on Executive Function in Depression: A Systematic Review

Effects of repetitive transcranial magnetic stimulation (rTMS) on cognitive impairment in depression: A systematic review and meta-analysis

OBJECTIVE

Cognitive dysfunction is a core symptom of depression and contributes significantly to functional and psychosocial impairment. However, pharmacotherapy has shown limited efficacy in alleviating these cognitive deficits. This study aimed to systematically evaluate the efficacy of repetitive transcranial magnetic stimulation (rTMS) in improving cognitive impairments in patients with depression.

METHODS

A literature search was conducted across PubMed, Embase, Web of Science, PsycINFO, and the Cochrane Library databases up to June 19, 2024. Studies were included if they met the following criteria: (1) participants were exclusively patients with unipolar depression, (2) both active rTMS and sham stimulation were administered in parallel groups, (3) sufficient data were available, and (4) the study design was a randomized controlled trial (RCT).

RESULTS

A total of 15 studies met the inclusion criteria. The meta-analysis revealed no significant improvement in cognitive impairment with active rTMS compared to sham rTMS across multiple cognitive domains, including global cognitive function, attention, working memory, psychomotor speed, language, visuospatial ability, learning and memory, and executive function.

CONCLUSION

Current evidence suggests that rTMS does not demonstrate substantial efficacy in alleviating cognitive dysfunction in patients with depression. Future research should focus on elucidating the underlying mechanisms of rTMS efficacy and optimizing stimulation protocols, including the precise targeting of stimulation sites, as well as refining frequency, intensity, and duration parameters to better address cognitive impairment.

Cognitive Outcomes After Transcranial Magnetic Stimulation for the Treatment of Late-Life Depression: Résultats cognitifs après la stimulation magnétique transcrânienne pour le traitement de la dépression chez les personnes âgées

BACKGROUND

Late-life depression (LLD) is often accompanied by cognitive impairment, which may persist despite antidepressant treatment. Repetitive transcranial magnetic stimulation (rTMS) is an efficacious treatment for depression, with potential benefits on cognitive functioning. However, research on cognitive effects is inconclusive, relatively sparse in LLD, and predominantly focused on group-level cognitive changes. This study aimed to explore individual-level cognitive changes following rTMS treatment in patients with LLD.

METHOD

Data were analyzed from 153 patients with LLD from the FOUR-D study (ClinicalTrials.gov identifier: NCT02998580) who received bilateral standard rTMS or theta burst stimulation (TBS) targeting the dorsolateral prefrontal cortex (DLPFC). Cognitive function was assessed pre- and post-treatment using measures of executive function, information processing speed, and learning and memory. Reliable change indices, adjusted for practice effects and test-retest reliability, were employed to evaluate individual-level cognitive changes. Chi-square tests examined if proportions of cognitive improvers differed from expected proportions.

RESULTS

Cognitive performance from baseline to end of treatment remained stable for most patients. Reliably improved performance was observed in 0.0% to 20.0% of participants across cognitive measures, while worsened performance was observed in 0.0% to 2.7%. A small but significant proportion (20.0%) of participants showed improvement in verbal learning.

CONCLUSIONS

Bilateral standard rTMS or TBS of the DLPFC in LLD yielded no substantial cognitive enhancing effects, although a small proportion showed improved verbal learning after treatment. Importantly, both interventions were cognitively safe with relatively stable performance across time. Future research is needed to explore approaches to enhance the cognitive benefits of standard rTMS and TBS in patients with LLD.

Slowing Cognitive Decline in Major Depressive Disorder and Mild Cognitive Impairment: A Randomized Clinical Trial

Importance

Older adults with major depressive disorder (MDD) or mild cognitive impairment (MCI) are at high risk for cognitive decline.

Objective

To assess the efficacy of cognitive remediation (CR) plus transcranial direct current stimulation (tDCS) targeting the prefrontal cortex in slowing cognitive decline, acutely improving cognition, and reducing progression to MCI or dementia in older adults with remitted MDD (rMDD), MCI, or both.

Design, Setting, and Participants

This randomized clinical trial was conducted at 5 academic hospitals in Toronto, Ontario, Canada. Participants were older adults who had rMDD (with or without MCI, age ≥65 y) or MCI without rMDD (age ≥60 y). Assessments were made at baseline, month 2, and yearly from baseline for 3 to 7 years.

Interventions

CR plus tDCS (hereafter, active) or sham plus sham 5 days a week for 8 weeks followed by twice-a-year 5-day boosters and daily at-home CR or sham CR.

Main Outcomes and Measures

The primary outcome was change in global composite cognitive score. Secondary outcomes included changes in 6 cognitive domains, moderating effect of the diagnosis, moderating effect of APOE ε4 status, change in composite score at month 2, and progression to MCI or dementia over time.

Results

Of 486 older adults who provided consent, 375 (with rMDD, MCI, or both) received at least 1 intervention session (mean [SD] age, 72.2 [6.4] years; 232 women [62%] and 143 men [38%]). Over a median follow-up of 48.3 months (range, 2.1-85.9), CR and tDCS slowed cognitive decline in older adults with rMDD or MCI (adjusted z score difference [active - sham] at month 60, 0.21; 95% CI, 0.07 to 0.35; likelihood ratio test [LRT] P = .006). In the preplanned primary analysis, CR and tDCS did not improve cognition acutely (adjusted z score difference [active - sham] at month 2, 0.06, 95% CI, -0.006 to 0.12). Similarly, the effect of CR and tDCS on delaying progression from normal cognition to MCI or MCI to dementia was weak and not significant (hazard ratio, 0.66; 95% CI, 0.40 to 1.08; P = .10). Preplanned analyses showed treatment effects for executive function (LRT P = .04) and verbal memory (LRT P = .02) and interactions with diagnosis (P = .01) and APOE ε4 (P < .001) demonstrating a larger effect among those with rMDD and in noncarriers of APOE ε4.

Conclusions and Relevance

The study showed that CR and tDCS, both targeting the prefrontal cortex, is efficacious in slowing cognitive decline in older adults at risk of cognitive decline, particularly those with rMDD (with or without MCI) and in those at low genetic risk for Alzheimer disease.

Trial Registration

ClinicalTrials.gov Identifier: NCT02386670.

Use of transcranial magnetic stimulation (TMS) for studying cognitive control in depressed patients: A systematic review

Major depressive disorder (MDD) is a debilitating mental disorder and the leading cause of disease burden. Major depressive disorder is associated with emotional impairment and cognitive deficit. Cognitive control, which is the ability to use perceptions, knowledge, and information about goals and motivations to shape the selection of goal-directed actions or thoughts, is a primary function of the prefrontal cortex (PFC). Psychotropic medications are one of the main treatments for MDD, but they are not effective for all patients. An alternative treatment is transcranial magnetic stimulation (TMS). Previous studies have provided mixed results on the cognitive-enhancing effects of TMS treatment in patients with MDD. Some studies have found significant improvement, while others have not. There is a lack of understanding of the specific effects of different TMS protocols and stimulation parameters on cognitive control in MDD. Thus, this review aims to synthesize the effectiveness of the TMS methods and a qualitative assessment of their potential benefits in improving cognitive functioning in patients with MDD. We reviewed 21 studies in which participants underwent a treatment of any transcranial magnetic stimulation protocol, such as repetitive TMS or theta-burst stimulation. One of the primary outcome measures was any change in the cognitive control process. Overall, the findings indicate that transcranial magnetic stimulation (TMS) may enhance cognitive function in patients with MDD. Most of the reviewed studies supported the notion of cognitive improvement following TMS treatment. Notably, improvements were predominantly observed in inhibition, attention, set shifting/flexibility, and memory domains. However, fewer significant improvements were detected in evaluations of visuospatial function and recognition, executive function, phonemic fluency, and speed of information processing. This review found evidence supporting the use of TMS as a treatment for cognitive deficits in patients with MDD. The results are promising, but further research is needed to clarify the specific TMS protocol and stimulation locations that are most effective.

Psychomotor retardation: What about the partial responders to magnetic transcranial stimulation in treatment resistant depression ?

OBJECTIVE

Psychomotor retardation is a core clinical component of Major Depressive Disorder responsible for disability and is known as a treatment response marker of biological treatments for depression. Our objective was to describe cognitive and motoric measures changes during a treatment by repetitive Transcranial Magnetic Stimulation (rTMS) within the THETAD-DEP trial for treatment-resistant depression (TRD), and compare those performances at the end of treatment and one month after between responders (>50% improvement on MADRS score), partial responders (25-50%) and non-reponders (no clinically relevant improvement). Our secondary aim was to investigate baseline psychomotor performances associated with non-response and response even partial.

METHODS

Fifty-four patients with treatment-resistant unipolar depression and treated by either high frequency 10 Hz rTMS or iTBS for 4 weeks (20 sessions) underwent assessment including French Retardation Rating Scale for Depression (ERD), Verbal Fluency test, and Trail Making Test A. before, just after treatment and one month later.

RESULTS

20 patients were responders (R, 21 partial responders (PR) and 13 non-responders (NR). rTMS treatment improved psychomotor performances in the R and PR groups unlike NR patients whose psychomotor performance was not enhanced by treatment. At baseline, participants, later identified as partial responders, showed significantly higher performances than non-responders.

CONCLUSION

Higher cognitivo-motor performances at baseline may be associated with clinical improvement after rTMS treatment. This work highlights the value of objective psychomotor testing for the identification of rTMS responders and partial responders, and thus may be useful for patient selection and protocol individualization such as treatment continuation for early partial responders.

The cognitive effects of adjunctive repetitive transcranial magnetic stimulation for late-onset depression: a randomized controlled trial with 4 week follow-up

Objectives

Cognitive impairment is common and linked to poor outcomes in patients with late-onset depression (LOD). The cognitive effects of repetitive transcranial magnetic stimulation (rTMS) for LOD are not well understood. This study aimed to investigate the effects of rTMS on cognitive function in elderly patients with LOD.

Methods

In total, 58 elderly patients (aged 60 to 75 years) with depression were enrolled and randomly assigned to an active rTMS group or a sham group. The participants received active or sham rTMS over the left dorsolateral prefrontal cortex for 4 weeks, 5 days a week, at a frequency of 10 Hz rTMS and 120% of the motor threshold (MT). Cognitive function was assessed using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) at baseline, the end of the 4 week treatment period, and at the 4 week follow-up.

Results

The active rTMS group showed significant improvements in immediate memory and attention scores on the RBANS compared to the sham group. However, no significant differences were observed between the two groups in other cognitive domains assessed by the RBANS. No serious adverse events related to rTMS treatment were observed.

Conclusion

Treatment with 120% MT rTMS was associated with improvement in cognitive defects related to the active phase of LOD. These findings suggest that rTMS could provide early improvements in cognitive function in clinical settings for elderly patients with LOD.Clinical trial registration: https://www.chictr.org.cn/showproj.html?proj=40698, identifier ChiCTR1900024445.

A pilot randomized sham controlled trial of bilateral iTBS for depression and executive function in older adults

INTRODUCTION

Executive function deficits (EFD) in late life depression (LLD) are associated with poor outcomes. Dysfunction of the cognitive control network (CCN) has been posited in the pathophysiology of LLD with EFD.

METHODS

Seventeen older adults with depression and EFD were randomized to iTBS or sham for 6 weeks. Intervention was delivered bilaterally using a recognized connectivity target.

RESULTS

A total of 89% (17/19) participants completed all study procedures. No serious adverse events occurred. Pre to post-intervention change in mean Montgomery-Asberg-depression scores was not different between iTBS or sham, p = 0.33. No significant group-by-time interaction for Montgomery-Asberg Depression rating scale scores (F _{3, 44}  = 0.51; p = 0.67) was found. No significant differences were seen in the effects of time between the two groups on executive measures: Flanker scores (F _{1, 14}  = 0.02, p = 0.88), Dimensional-change-card-sort scores F _{1, 14}  = 0.25, p = 0.63, and working memory scores (F _{1, 14}  = 0.98, p = 0.34). The Group-by-time interaction effect for functional connectivity (FC) within the Fronto-parietal-network was not significant (F _{1, 14}  = 0.36, p = 0.56). No significant difference in the effect-of-time between the two groups was found on FC within the Cingulo-opercular-network (F _{1, 14}  = 0, p = 0.98).

CONCLUSION

Bilateral iTBS is feasible in LLD. Preliminary results are unsupportive of efficacy on depression, executive function or target engagement of the CCN. A future Randomized clinical trial requires a larger sample size with stratification of cognitive and executive variables and refinement in the target engagement.

Remission of symptoms is not equal to functional recovery: Psychosocial functioning impairment in major depression

The ultimate goal of depression treatment is to achieve functional recovery. Psychosocial functioning is the main component of functional impairment in depressed patients. The concept of psychosocial functioning has an early origin; however, its concept and connotation are still ambiguous, which is the basic and key problem faced by the relevant research and clinical application. In this study, we start from the paradox of symptoms remission and functional recovery, describe the concept, connotation, and characteristics of psychosocial functioning impairment in depressed patients, and re-emphasize its importance in depression treatment to promote research and clinical applications related to psychosocial functioning impairment in depressed patients to achieve functional recovery.

Repetitive Transcranial Magnetic Stimulation for Comorbid Major Depressive Disorder and Alcohol Use Disorder

Major depressive disorder (MDD) and alcohol use disorder (AUD) are leading causes of disability, and patients are frequently affected by both conditions. This comorbidity is known to confer worse outcomes and greater illness severity. Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive neuromodulation method that has demonstrated antidepressant effects. However, the study of rTMS for patients with MDD and commonly associated comorbidities, such as AUD, has been largely overlooked, despite significant overlap in clinical presentation and neurobiological mechanisms. This narrative review aims to highlight the interrelated aspects of the literature on rTMS for MDD and rTMS for AUD. First, we summarize the available evidence on the effectiveness of rTMS for each condition, both most studied through stimulation of the dorsolateral prefrontal cortex (DLPFC). Second, we describe common symptom constructs that can be modulated by rTMS, such as executive dysfunction, that are transdiagnostic across these disorders. Lastly, we describe promising approaches in the personalization and optimization of rTMS that may be applicable to both AUD and MDD. By bridging the gap between research efforts in MDD and AUD, rTMS is well positioned to be developed as a treatment for the many patients who have both conditions concurrently.

Cognitive Control Deficits in Depression: A Novel Target to Improve Suboptimal Outcomes in Childhood

Cognitive control deficits are one of three primary endophenotypes in depression, and the enhanced targeting of these deficits in clinical and research work is expected to lead to improved depression outcomes. Cognitive control is a set of self-regulatory processes responsible for goal-oriented behavior that predicts clinical/functional outcomes across the spectrum of brain-based disorders. In depression, cognitive control deficits emerge by the first depressive episode, persist during symptom remission, and worsen over the course of depression. In addition, the presence of these deficits predicts a poor response to evidence-based depression treatments, including psychotherapy and antidepressant medication. This is particularly relevant to childhood depression, as 1%-2% of children are diagnosed with depression, yet there are very limited evidence-based treatment options. Cognitive control deficits may be a previously underaddressed factor contributing to poor outcomes, although there remains a dearth of research examining the topic. The investigators describe the prior literature on cognitive control in depression to argue for the need for increased focus on this endophenotype. They then describe cognitive control-focused clinical and research avenues that would likely lead to improved treatments and outcomes for this historically undertreated aspect of childhood depression.

Impact of Repetitive Transcranial Magnetic Stimulation (rTMS) on Theory of Mind and Executive Function in Major Depressive Disorder and Its Correlation with Brain-Derived Neurotrophic Factor (BDNF): A Randomized, Double-Blind, Sham-Controlled Trial

BACKGROUND

Studies have implicated hypofrontality in the pathogenesis of impaired theory of mind (ToM) and executive function (EF) in major depressive disorder (MDD). These symptoms are usually resistant to treatment. Repetitive transcranial magnetic stimulation (rTMS) has been shown to reverse hypofrontality. Moreover, BDNF is an effective biomarker of antidepressant effects, but there have been very few studies on the correlation between BDNF and rTMS. We aimed to evaluate the efficacy of 20 sessions of a 10 Hz unilateral rTMS intervention over the left dorsolateral prefrontal cortex (DLPFC) in improving ToM and EF in patients with MDD and its correlation with BDNF.

METHODS

A total of 120 MDD patients were enrolled in this randomized, sham-controlled, double-blind trial. Each participant received 20 sessions of rTMS at 10 Hz frequency through the active or the sham coil over 4 weeks. ToM was assessed with the facial emotion identification test (FEIT) and hinting task (HT). EF was assessed with the Wisconsin card sorting test (WCST). BDNF assessments were carried out at baseline and 2-, 4-, 12-, and 24-week follow-ups.

RESULTS

The improvement in the ToM (FEIT, HT) in the active rTMS group was significantly different from that in the sham rTMS group (F = 18.09, p < 0.001; F = 5.02, p = 0.026). There were significant differences in the WCST (categories completed, response errors, response perseverative errors, non-response perseverative errors) after logarithmic transformation at different time points in the active rTMS group (F = 14.71, p < 0.001; F = 5.99, p = 0.046; F = 8.90, p = 0.031; F = 2.31, p = 0.048). However, there was no significant difference in log transformed BDNF concentration between the two groups (t = 0.07 to t = 1.29, p > 0.05). BDNF was negatively correlated with WCST categories completed at the 24th week (r = -0.258, p = 0.046).

CONCLUSIONS

The results show that rTMS may improve the ToM and EF of patients with MDD and there was no significant correlation with serum BDNF concentration. RTMS can not only be used for treatment of patients with MDD but also has a positive effect on ToM and EF.

Neural substrates of the executive function construct, age-related changes, and task materials in adolescents and adults: ALE meta-analyses of 408 fMRI studies

To explore the neural substrates of executive function (EF), we conducted an activation likelihood estimation meta-analysis of 408 functional magnetic resonance imaging studies (9639 participants, 7587 activation foci, 518 experimental contrasts) covering three fundamental EF subcomponents: inhibition, switching, and working memory. Our results found that activation common to all three EF subcomponents converged in the multiple-demand network across adolescence and adulthood. The function of EF with the multiple-demand network involved, especially for the prefrontal cortex and the parietal regions, could not be mature until adulthood. In adolescents, only working memory could be separable from common EF, whereas in adults, the three EF subcomponents could be separable from common EF. However, findings of switching in adolescents should be treated with substantial caution and may be exploratory due to limited data available on switching tasks. For task materials, inhibition and working memory showed both domain generality and domain specificity, undergirded by the multiple-demand network, as well as different brain regions in response to verbal and nonverbal task materials, respectively. In contrast, switching showed only domain generality with no activation specialized for either verbal or nonverbal task materials. These findings, taken together, support and contribute to the unitary-diverse nature of EF such that EF should be interpreted in an integrative model that relies on the integration of the EF construct, development, and task materials.

The Effects of Repetitive Transcranial Magnetic Stimulation Antidepressant Response on Cold Cognition: A Single-Arm Prospective Longitudinal Study

PURPOSE

The cognitive neuropsychological model of depression suggests that the cognitive deficits observed in depressed subjects are the result of attenuated top-down cognitive control resulting in increased bottom-up emotional processing. Remediation of cognitive impairments in cold cognition has been proposed as a valuable treatment for depression. The study aimed to examine the effects of clinical response to repetitive transcranial magnetic stimulation (rTMS) on cold cognition over the course of 8 weeks in medication-refractory depressed subjects.

MATERIALS AND METHODS

Twenty-two medication-refractory depressed subjects received twenty sessions of high-frequency rTMS targeting the left dorsolateral prefrontal cortex, one of the key nodes of the cognitive control network. Cold cognition and antidepressant treatment response were monitored at baseline, week 2, 4 and 8. Clinical response was defined as ≥50% reduction in Montgomery-Åsberg Depression Rating Scale score at week 8. Longitudinal changes in cold cognition were modeled using (generalized) linear mixed models. It was hypothesized that the excitatory effects of rTMS would improve cognition in the domains of executive function, memory, and attention. Additionally, responders were expected to show larger cognitive improvements than nonresponders.

RESULTS

A decrease in median latency was observed on a task that measured executive function, irrespective of treatment response status. Further, responders showed significantly larger improvements in A-Prime (the ability to detect target sequences) on a sustained attention task. Post hoc analysis indicated higher levels of rumination in non-responders.

CONCLUSION

Our findings suggest that distractions during tasks with low perceptual complexity affected nonresponders disproportionately possibly due to higher rumination levels. Overall, cold cognition in medication-resistant depressed subjects was minimally affected by rTMS, substantiating the safety of rTMS treatment.

LIMITATIONS

The sample size was small, and the study did not include a control group.

A Lifespan Model of Interference Resolution and Inhibitory Control: Risk for Depression and Changes with Illness Progression

The cognitive processes involved in inhibitory control accuracy (IC) and interference resolution speed (IR) or broadly - inhibition - are discussed in this review, and both are described within the context of a lifespan model of mood disorders. Inhibitory control (IC) is a binary outcome (success or no for response selection and inhibition of unwanted responses) for any given event that is influenced to an extent by IR. IR refers to the process of inhibition, which can be manipulated by task design in earlier and later stages through use of distractors and timing, and manipulation of individual differences in response proclivity. We describe the development of these two processes across the lifespan, noting factors that influence this development (e.g., environment, adversity and stress) as well as inherent difficulties in assessing IC/IR prior to adulthood (e.g., cross-informant reports). We use mood disorders as an illustrative example of how this multidimensional construct can be informative to state, trait, vulnerability and neuroprogression of disease. We present aggregated data across numerous studies and methodologies to examine the lifelong development and degradation of this subconstruct of executive function, particularly in mood disorders. We highlight the challenges in identifying and measuring IC/IR in late life, including specificity to complex, comorbid disease processes. Finally, we discuss some potential avenues for treatment and accommodation of these difficulties across the lifespan, including newer treatments using cognitive remediation training and neuromodulation.

A systematic review and meta-analysis of rTMS effects on cognitive enhancement in mild cognitive impairment and Alzheimer's disease

Repetitive transcranial magnetic stimulation (rTMS), a noninvasive brain stimulation technique, has emerged as a promising treatment for mild cognitive impairment (MCI) and Alzheimer's disease (AD). Currently, however, the effectiveness of this therapy is unclear because of the low statistical power and heterogeneity of previous trials. The purpose of the meta-analysis was to systematically characterize the effectiveness of various combinations of rTMS parameters on different cognitive domains in patients with MCI and AD. Thirteen studies comprising 293 patients with MCI or AD were included in this analysis. Random-effects analysis revealed an overall medium-to-large effect size (0.77) favoring active rTMS over sham rTMS in the improvement of cognitive functions. Subgroup analyses revealed that (1) high-frequency rTMS over the left dorsolateral prefrontal cortex and low-frequency rTMS at the right dorsolateral prefrontal cortex significantly improved memory functions; (2) high-frequency rTMS targeting the right inferior frontal gyrus significantly enhanced executive performance; and (3) the effects of 5-30 consecutive rTMS sessions could last for 4-12 weeks. Potential mechanisms of rTMS effects on cognitive functions are discussed.

Evidence-based guidelines on the therapeutic use of repetitive transcranial magnetic stimulation (rTMS): An update (2014-2018)

A group of European experts reappraised the guidelines on the therapeutic efficacy of repetitive transcranial magnetic stimulation (rTMS) previously published in 2014 [Lefaucheur et al., Clin Neurophysiol 2014;125:2150-206]. These updated recommendations take into account all rTMS publications, including data prior to 2014, as well as currently reviewed literature until the end of 2018. Level A evidence (definite efficacy) was reached for: high-frequency (HF) rTMS of the primary motor cortex (M1) contralateral to the painful side for neuropathic pain; HF-rTMS of the left dorsolateral prefrontal cortex (DLPFC) using a figure-of-8 or a H1-coil for depression; low-frequency (LF) rTMS of contralesional M1 for hand motor recovery in the post-acute stage of stroke. Level B evidence (probable efficacy) was reached for: HF-rTMS of the left M1 or DLPFC for improving quality of life or pain, respectively, in fibromyalgia; HF-rTMS of bilateral M1 regions or the left DLPFC for improving motor impairment or depression, respectively, in Parkinson's disease; HF-rTMS of ipsilesional M1 for promoting motor recovery at the post-acute stage of stroke; intermittent theta burst stimulation targeted to the leg motor cortex for lower limb spasticity in multiple sclerosis; HF-rTMS of the right DLPFC in posttraumatic stress disorder; LF-rTMS of the right inferior frontal gyrus in chronic post-stroke non-fluent aphasia; LF-rTMS of the right DLPFC in depression; and bihemispheric stimulation of the DLPFC combining right-sided LF-rTMS (or continuous theta burst stimulation) and left-sided HF-rTMS (or intermittent theta burst stimulation) in depression. Level A/B evidence is not reached concerning efficacy of rTMS in any other condition. The current recommendations are based on the differences reached in therapeutic efficacy of real vs. sham rTMS protocols, replicated in a sufficient number of independent studies. This does not mean that the benefit produced by rTMS inevitably reaches a level of clinical relevance.

Efficacy of repetitive transcranial magnetic stimulation in treatment-resistant depression: the evidence thus far

Depression is a common mental disorder, which attributes to significant morbidity, disability and burden of care. A significant number of patients with depression still remain symptomatic after adequate trials of antidepressant treatment as well as psychotherapy, which is often referred to as treatment-resistant depression. Neuromodulation techniques-like electroconvulsive therapy, vagus nerve stimulation, transcranial magnetic stimulation (TMS) and transcranial direct current stimulation, may be useful augmenting techniques in depression, mostly recommended for treatment-resistant cases. Robust evidence exists regarding the efficacy of electroconvulsive therapy in the management of treatment-resistant depression; however, other techniques are understudied. TMS has been increasingly studied in various psychiatric disorders including depression. It has been approved by the US Food and Drug Administration for use in major depressive disorder. Over the past two decades, TMS has been studied in diverse groups of the population with depression using several research designs. This article gives an overview of the efficacy of repetitive TMS in treatment-resistant depression with the recent evidence.

An inverse relationship between cortical plasticity and cognitive inhibition in late-life depression

Executive dysfunction is a common and disabling component of late-life depression (LLD), yet its neural mechanisms remain unclear. In particular, it is not yet known how executive functioning in LLD relates to measures of cortical physiology that may change with age and illness, namely cortical inhibition/excitation and plasticity. Here, we used transcranial magnetic stimulation (TMS) to measure cortical inhibition/excitation (n = 51), and the potentiation of cortical activity following paired associative stimulation, which is thought to reflect long-term potentiation (LTP)-like cortical plasticity (n = 32). We assessed the correlation between these measures of cortical physiology and two measures of executive functioning: cognitive inhibition, assessed using the Delis-Kaplan Executive Function System Color-Word Interference ["Stroop"] Test, and cognitive flexibility, assessed using the Trail Making Test. Correlations with recall memory and processing speed were also performed to assess the specificity of any associations to executive functioning. A significant correlation was found between greater LTP-like cortical plasticity and poorer cognitive inhibition, a core executive function (rp = -0.56, p < 0.001). We did not observe significant associations between cortical inhibition/excitation and executive functioning, or between any neurophysiological measure and cognitive flexibility, memory, or processing speed. Our finding that elevated cortical plasticity is associated with diminished cognitive inhibition emphasizes the importance of balanced synaptic strengthening to healthy cognition. More specifically, our findings suggest that hyper-excitability of cortical circuits following repeated cortical activation may promote inappropriate prepotent responses in LLD. LTP-like cortical plasticity might therefore represent a neural mechanism underlying an inhibitory control cognitive endophenotype of LLD.

Management of Late-Life Depression in the Context of Cognitive Impairment: a Review of the Recent Literature

PURPOSE OF REVIEW

Evidence regarding the treatment of late-life depression is not necessarily generalizable to persons with a neurocognitive disorder and comorbid depression. Thus, this article reviews recent evidence that pertains to the treatment of depression in older adults with neurocognitive disorders, and synthesizes and critically analyzes this literature to identify methodological issues and gaps for the purpose of future research.

RECENT FINDINGS

Controlled trials and meta-analyses examining depression treatment in neurocognitive disorders, published between 2015 and 2019 (N = 16 reports), can be divided into those addressing pharmacotherapy, psychological and behavioral therapy, and somatic therapy. The evidence generally does not support benefit of antidepressant medication over placebo in treating depressive disorders in dementia. No pharmacological studies since 2015 have examined antidepressant medication in participants with mild cognitive impairment (MCI). Problem adaptation therapy demonstrates efficacy for depression in MCI and mild dementia. Other psychological and behavioral interventions for depressive symptoms in dementia demonstrate mixed findings. The only somatic treatment trials published since 2015 have assessed bright light therapy, with positive findings but methodological limitations. Psychological, behavioral, and somatic treatments represent promising treatment options for depression in neurocognitive disorders, but further studies are needed, particularly in participants with depressive disorders rather than subclinical depressive symptoms. Little is known about the treatment of depression in patients with MCI, and rigorous identification of MCI in late-life depression treatment trials will help to advance knowledge in this area. Addressing methodological issues, particularly the diagnosis and measurement of clinically significant depression in dementia, will help to move the field forward.

A double-blind pilot dosing study of low field magnetic stimulation (LFMS) for treatment-resistant depression (TRD)

BACKGROUND

Low field magnetic stimulation is a potentially rapid-acting treatment for depression with mood-enhancing effects in as little as one 20-min session. The most convincing data for LFMS has come from treating bipolar depression. We examined whether LFMS also has rapid mood-enhancing effects in treatment-resistant major depressive disorder, and whether these effects are dose-dependent.

OBJECTIVE/HYPOTHESIS

We hypothesized that a single 20-min session of LFMS would reduce depressive symptom severity and that the magnitude of this change would be greater after three 20-min sessions than after a single 20-min session.

METHODS

In a double-blind randomized controlled trial, 30 participants (age 21-65) with treatment-resistant depression were randomized to three 20-min active or sham LFMS treatments with 48 h between treatments. Response was assessed immediately following LFMS treatment using the 6-item Hamilton Depression Rating Scale (HAMD-6), the Positive and Negative Affect Scale (PANAS) and the Visual Analog Scale.

RESULTS

Following the 3rd session of LFMS, the effect of LFMS on VAS and HAMD-6 was superior to sham (F (1, 24) = 7.45, p = 0.03, Bonferroni-Holm corrected; F (1, 22) = 6.92, p = 0.03, Bonferroni-Holm corrected, respectively). There were no differences between sham and LFMS following the initial or second session with the effect not becoming significant until after the third session.

CONCLUSIONS

Three 20-min LFMS sessions were required for active LFMS to have a mood-enhancing effect for individuals with treatment-resistant depression. As this effect may be transient, future work should address dosing schedules of longer treatment courses as well as biomarker-based targeting of LFMS to optimize patient selection and treatment outcomes.

Time to remission analysis for major depressive disorder after repetitive transcranial magnetic stimulation (rTMS)

We previously examined the efficacy of rTMS for major depressive disorder in an applied clinical practice. Clinical response was related to severity of depression as well as the rTMS instrument utilized suggesting a relationship to instrument or magnetic field parameters and individual factors. The effectiveness of repetitive transcranial magnetic stimulation (rTMS) in the treatment of major depressive disorder was further evaluated using Log-Rank statistics for time to remission outcomes. A follow-up retrospective medical records study was carried out on patients with major depressive disorder undergoing rTMS therapy at AwakeningsKC Clinical Neuroscience Institute (CNI), a suburban tertiary psychiatric clinic. Cox Proportional Hazard with Log-Rank statistics were applied and the time course to clinical remission was evaluated over a 6-week period with respect to age, gender, and depression severity. Clinical response was observed referencing two different rTMS instruments (MagVenture; NeuroStar). Time to remission studies of 247 case reports (N=98 males; N=149 females) showed consistently greater clinically defined remission rates after 6 weeks of rTMS treatment for patients using the MagVenture vs NeuroStar instrument. Patients previously admitted for inpatient psychiatric hospitalization exhibited higher response rates when treated with the MagVenture rTMS unit. Stepwise Cox Proportional Hazards Regression final model of time to remission included rTMS unit, inpatient psychiatric hospitalization and obese body habitus. Response to rTMS in applied clinical practice is related to severity of psychiatric illness and may require consideration of magnetic field parameters of the rTMS unit with respect to individual factors such as sex or body composition.

Repetitive transcranial magnetic stimulation (rTMS) using different TMS instruments for major depressive disorder at a suburban tertiary clinic

Repetitive transcranial magnetic stimulation (rTMS) is a neurostimulatory technique used to modulate orbital frontal corticostriatal (OFC) activity and clinical symptomatology for psychiatric disorders involving OFC dysfunction. We examined the effectiveness of rTMS in the treatment of major depressive disorder in an applied clinical setting (Awakening KC CNI) to assess efficacy and optimize rTMS parameters within clinical practice. A retrospective review of medical records was carried out on patients with major depressive disorder undergoing rTMS therapy at Awakenings KC Clinical Neuroscience Institute (CNI), a suburban tertiary psychiatric clinic. A detailed de-identified data set of clinical outcomes was compiled. Patient Health Questionnaire 9 (PHQ-9) total score, clinical remission rate and week achieved were evaluated over 6 weeks of treatment to assess clinical response referencing two different rTMS instruments (MagVenture; NeuroStar). Our survey included 247 participants from males (N=98) and females (N=149) with average baseline PHQ-9 scores of 21.7±4, classified as severe depression. Clinically rated remission rates of 72% were achieved in 3.1±1.0 weeks and associated with prior history of psychiatric hospitalization, suicide attempts and substance use disorder. Average baseline PHQ- 9 scores decreased significantly over time with proportionately greater remission rates achieved for patients treated using the MagVenture over NeuroStar instrument. rTMS in applied clinical practice is efficacious over a wide range of settings and patients. Clinical response was related to severity of depression symptoms (e.g., prior hospitalization; suicide attempts) validating efficacy in critically ill groups. Clinical response may be impacted by rTMS instrument, magnetic field parameters or individual factors.

Effectiveness of the prefrontal repetitive transcranial magnetic stimulation on cognitive profiles in depression, schizophrenia, and Alzheimer's disease: A systematic review

Repetitive transcranial magnetic stimulation (rTMS) is an effective clinical intervention for various neuropsychiatric diseases. However, it is still unclear whether rTMS has an effect on cognitive functioning. In this review, we aimed to systematically evaluate the cognitive effects of rTMS in depression, schizophrenia, and Alzheimer's disease. We searched PubMed (1996-2018) under the set terms to review randomized controlled trials (RCT) to examine the effectiveness of rTMS administered to the dorsolateral prefrontal cortex (DLPFC) and evaluated cognitive functions in patients with depression, schizophrenia, and Alzheimer's disease. Two authors reviewed each article and came to consensus on the inclusion and exclusion criteria. All eligible studies were reviewed, duplicates were removed, and data were extracted individually. The search identified 579 articles, 31 of which met inclusion and exclusion criteria. Among them, 15 were conducted in patients with depression, 11 in patients with schizophrenia, and 5 in patients with Alzheimer's disease. Specifically, 6 studies demonstrated a significant improvement of executive function across these diseases. Further, no evidence for cognitive adverse effects was found in these included rTMS studies. Although the heterogeneity between studies in terms of cognitive measures applied, stimulation parameters, and participants limits the ability to generalize conclusions, this review demonstrated that prefrontal rTMS could exert pro-cognitive effects on executive function and attention in some patients with depression but inconsistent cognitive impacts in any of the examined domains especially in patients with schizophrenia and Alzheimer's disease. The results warrant further rTMS studies that include systematic assessment of cognition across various neuropsychiatric diseases.

Efficacy, tolerability, and cognitive effects of deep transcranial magnetic stimulation for late-life depression: a prospective randomized controlled trial

Late-life depression (LLD) is a growing worldwide problem due to demographic changes, with limited treatment options due to high rates of pharmacotherapy adverse effects, accessibility of psychotherapy, and tolerability of electroconvulsive therapy. Novel neuromodulation techniques, such as repetitive transcranial magnetic stimulation (rTMS), may overcome these limitations. The objective of this study is to determine the efficacy, tolerability, and cognitive effects of high-dose deep rTMS in LLD. In this study we randomized older adults between 60 and 85 years old with major depressive disorder (MDD) to sham or active deep rTMS (H1 coil, 6012 pulses, 18 Hz, 120% of resting motor threshold) delivered over the dorsolateral and ventrolateral prefrontal cortex 5 days per week over 4 weeks. Our primary outcome was remission of depression in an intention-to-treat analysis. We also assessed change in cognitive functioning with rTMS treatment and tolerability based on adverse effects. Fifty-two participants were randomized to active (n = 25) or sham H1 coil (n = 27). Remission rate was significantly higher with active than sham rTMS (40.0% vs 14.8%) with a number needed to treat of 4.0 (95% CI: 2.1-56.5). There was no change on any measure of executive function and no serious adverse events. Adverse effect profiles were similar between active and sham rTMS, except for reports of pain being significantly more common in the active condition (16.0% vs 0%). High-dose deep rTMS appears to be safe, well tolerated, and efficacious in the treatment of LLD.