Deep transcranial magnetic stimulation for treatment-resistant bipolar depression: a case report of acute and maintenance efficacy

Deep transcranial magnetic stimulation for treatment-resistant depression: A systematic review and meta-analysis of randomized controlled studies

The efficacy and safety of deep transcranial magnetic stimulation (dTMS) in treating treatment-resistant depression (TRD) are unknown. Up to June 21, 2023, we conducted a systematic search for RCTs, and then extracted and synthesized data using random effects models. Five RCTs involving 507 patients with TRD (243 in the active dTMS group and 264 in the control group) were included in the present study. The active dTMS group showed significantly higher study-defined response rate (45.3% versus 24.2%, n = 507, risk ratio [RR] = 1.87, 95% confidence interval [CI]: 1.21-2.91, I2 = 53%; P = 0.005) and study-defined remission rate (38.3% versus 14.4%, n = 507, RR = 2.37, 95%CI: 1.30-4.32, I2 = 58%; P = 0.005) and superiority in improving depressive symptoms (n = 507, standardized mean difference = -0.65, 95%CI: -1.11--0.18, I2 = 82%; P = 0.006) than the control group. In terms of cognitive functions, no significant differences were observed between the two groups. The two groups also showed similar rates of other adverse events and all-cause discontinuations (P > 0.05). dTMS is an effective and safe treatment strategy for the management of patients with TRD.

Low-frequency rTMS modulated the excitability and high-frequency firing in hippocampal neurons of the Alzheimer's disease mouse model

Repetitive transcranial magnetic stimulation (rTMS), a non-invasive brain stimulation technique, holds potential for applications in the treatment of Alzheimer's disease (AD). This study aims to compare the therapeutic effects of rTMS at different frequencies on Alzheimer's disease and explore the alterations in neuronal electrophysiological properties throughout this process. APP/PS1 AD mice were subjected to two rTMS treatments at 0.5 Hz and 20 Hz, followed by assessments of therapeutic outcomes through the Novel Object Recognition (NOR) and Morris Water Maze (MWM) tests. Following this, whole-cell patch-clamp techniques were used to record action potential, voltage-gated sodium channel currents, and voltage-gated potassium channel currents in dentate gyrus granule neurons. The results show that AD mice exhibit significant cognitive decline compared to normal mice, along with a pronounced reduction in neuronal excitability and ion channel activity. Both frequencies of rTMS treatment partially reversed these changes, demonstrating similar therapeutic efficacy. Furthermore, the investigation indicates that low-frequency magnetic stimulation inhibited the concentrated firing of early action potentials in AD.

The Koukopoulos mixed depression rating scale (KMDRS) and the assessment of mixed symptoms during the perinatal period

BACKGROUND

Mixed symptoms in depression may underlie bipolar diathesis rather than unipolarity. Uncovering mixed depression (MxD) is crucial for appropriate management, especially in the perinatal period, as it may affect treatment planning and impact future child development. We used a scale specific for identifying MxD and tested its validity in pregnant and postpartum women with depression.

METHODS

Women developing a major depressive episode (MDE) during their perinatal period extending from pregnancy to one year postpartum from November-2012 through June-2019 were assessed with BPRS-18, EPDS, CGI-S, GAF, HAM-A, HAM-D, Koukopoulos' Mixed Depression Rating Scale (KMDRS), TEMPS, and YMRS. They were classified, based on KMDRS criteria, as with mixed (MxD) or without (nonMxD) mixed symptoms. We conducted ROC analysis and performed factor analysis of the KMDRS.

RESULTS

Of 45 included, MxD (N = 19) were biased towards diagnosis of bipolar disorder and nonMxD (N = 26) towards major depressive disorder. Other sociodemographic variables did not differ significantly between MxD and nonMxD. MxD scored higher on total YMRS, BPRS, and KMDRS, and on KMDRS-6 Subjective Feelings of Irritability and KMDRS-12 Suicidal Impulsiveness items. The KMDRS correlated in the entire sample, in MxD and nonMxD, with the YMRS and the BPRS, while correlating with the HAM-D in nonMxD only. The KMDRS showed acceptable AUC distribution, with a 68% sensitivity and 58% specificity. Best-fit was three-factor-structure, explaining 54.66% of cumulative variance.

LIMITATIONS

Small sample and cross-sectional design.

CONCLUSIONS

The KMDRS is fit for investigating MxD along with the YMRS and the BPRS in perinatal women with a MDE.

Clinical Picture, Temperament, and Personality of Patients with Mixed States

The construct of mixed states is a robust clinical entity with a high variability of prevalence according to different diagnostic criteria. Despite the changes over the years, current official diagnostic criteria still have poor clinical usefulness. Premorbid characteristics with a potential high clinical importance such as temperament, personality, and emotional reactivity are understudied in patients with mixed states and excluded from the current nosologic systems. The authors provide an overview of current nosography and clinical pictures of mixed states and discuss the role of temperament, personality, and emotional reactivity in mixed states.

Mixed States: Historical Impact and Evolution of the Concept

Mixed states have been discussed for more than 2 millennia. The theoretic conception of the coexistence of presumably opposite symptoms of mood or of different psychic domains is well established, although obscured by the presumed separation between bipolar and depressive disorders. Moreover, the lack of response to treatments and severe psychopathology raise important issues requiring urgent solution. The aim of this article was to review the development of the concept of mixed states from the classic literature to modern nosologic systems and to claim for the need of a new paradigm to address the still-open issues about mixed states.

Drug Treatment of Trichotillomania (Hair-Pulling Disorder), Excoriation (Skin-picking) Disorder, and Nail-biting (Onychophagia)

BACKGROUND

Trichotillomania (TTM), excoriation (or skin-picking) disorder and some severe forms of onychophagia are classified under obsessive-compulsive and related disorders. There are different interacting neurotransmitter systems involved in the pathophysiology of impulse-control disorders, implicating noradrenaline, serotonin, dopamine, opioid peptides and glutamate, hence investigators focused on drugs able to act on these transmitters. Our aim was to critically review the efficacy of the drugs employed in impulse-control disorders.

METHODS

We searched for controlled drug trials to treat TTM, excoriation, and/or nail-biting six databases (PubMed, Cochrane, Scopus, CINAHL, PsycINFO/PsycARTICLES, and Web of Science), using the search strategy: (trichotillomania OR "excoriation disorder" OR "face picking" OR "skin picking" OR "hair pulling" OR onychophagia OR "nail-biting") AND drug treatment on 12 March 2018 for all databases. We followed in our method of identifying relevant literature the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement.

RESULTS

SSRIs and clomipramine are considered first-line in TTM. In addition, family members of TTM patients are often affected by obsessive-compulsive spectrum disorders. Other drugs used in the treatment of TTM are lamotrigine, olanzapine, N-Acetylcysteine, inositol, and naltrexone.

CONCLUSION

The treatment of TTM, excoriation disorder and nail-biting is still rather disappointing. Conjectures made from preclinical studies and the relative pathophysiological hypotheses found poor confirmations at a clinical level. There is a need for further studies and the integration of pharmacological and psychotherapeutic. Our results point to the need of integrating personalised medicine principles in the treatment of these patients.

Factors Associated with Non-Remission in Bipolar Disorder: The Multicenter Treatment Survey for Bipolar Disorder in Psychiatric Outpatient Clinics (MUSUBI)

PURPOSE

The aim of this study was to identify factors associated with non-remission in bipolar disorder.

PATIENTS AND METHODS

The multicenter treatment survey for bipolar disorder in psychiatric outpatient clinics (MUSUBI) study used a questionnaire administered at 176 clinics throughout Japan from September to October 2016. Clinic psychiatrists performed a retrospective medical record survey of consecutive cases with bipolar disorder. Patients were considered to be in remission if they met all of the following criteria: they were not in a mixed state, their manic or depressive symptoms were either borderline or nonexistent (corresponding to 2 or 1 points on the Clinical Global Impressions Scale, Bipolar Version), and their psychiatrists clinically considered them to be in remission. Enrolled patients were classified into remitters group and non-remitters group and demographic and clinical characteristics were contrasted between the groups. Non-remitters were compared with remitters, using a series of logistic regression analyses.

RESULTS

A total of 3130 patients (1420 men; mean age: 50.3 years) were included in this study; 1307 patients (41.8%) were in remission. Of the remaining 1823 patients, 1260 (40.3%) had mild to severe depression, 261 (8.3%) suffered from manic or hypomanic episodes, and 302 (9.6%) were in a mixed state. Logistic regression analyses found the following eight factors to be significantly correlated with non-remission in patients with bipolar disorder: female gender, younger age, unemployed status, rapid cycling pattern, comorbid alcohol/substance abuse, poorer social function, lithium non-use, and antidepressant use.

CONCLUSION

The MUSUBI study, the largest nationwide investigation on bipolar disorder, identified eight clinically relevant factors associated with non-remission in bipolar patients. They have important clinical implications; further prospective studies are necessary to replicate these findings and to guide better managements for those in serious needs.

Stabilization Beyond Mood: Stabilizing Patients With Bipolar Disorder in the Various Phases of Life

BACKGROUND

There are different ways to define stabilization and currently, the main standpoint regards it as no-depression/no-mania. Furthermore, each person is physiologically different from childhood to adulthood, and in old age, thus the meaning of stabilization should take into account both growth and maturity. We aimed to review systematically studies focusing on mood stabilization in all phases of bipolar disorder (BD) and across all life phases, including pregnancy and the perinatal period, which is still a different phase in women's life cycles.

METHODS

We carried out a PubMed search focusing on studies of bipolar disorder treated with drugs and aimed at stabilization with the following search strategy stabiliz*[ti] OR stabilis*[ti] OR stable[ti] OR stability[ti]) AND mood[ti] AND bipolar. In conducting our review, we followed the PRISMA statement. Agreement on inclusion was reached by consensus of all authors through a Delphi rounds procedure.

RESULTS

The above search strategy produced 509 records on January 25, 2020. Of them, 58 fitted our inclusion criteria and were discussed. The eligible studies spanned from September 1983 to July 6, 2019.

CONCLUSIONS

No clear-cut indications could be drawn due to a number of limitations involving sample inconsistency and different methods of assessing mood stabilization. The evidence collected so far does not allow recommended treatments for Adolescents, pregnant or perinatal women, and aged patients. However, adults, not within these groups, better focused upon. For their manic/mixed phases, second generation antipsychotic drugs may be useful in the short-to-medium run, alone or combined with mood stabilizers (MSs). However, MSs, and especially lithium, continue to be pivotal in chronic treatment. Bipolar depression should rely on MSs, but an antidepressant may be added on and can prove to be helpful. However, there are concerns with the tendency of antidepressants to induce the opposite polarity or mood instability, rendering the need for concurrent MS prescription mandatory.

Pitfalls in Geriatric Prescribing: Antidepressants and Extreme Sedation

In this study, a case is presented in which initiation of an antidepressant drug was associated with an episode of extreme sedation. This case provides an opportunity to highlight possible pitfalls in geriatric prescribing.

Add-on high frequency deep transcranial magnetic stimulation (dTMS) to bilateral prefrontal cortex in depressive episodes of patients with major depressive disorder, bipolar disorder I, and major depressive with alcohol use disorders

BACKGROUND

Dorsolateral prefrontal cortex (DLPFC) is critically involved in mood and alcohol use disorders.

OBJECTIVE

We aimed to investigate the safety of intervention with add-on bilateral prefrontal high-frequency deep transcranial magnetic stimulation (dTMS) and between-group differences in treatment response in patients with different types of depressive episodes, including major depressive episodes in the course of major depressive disorder (MDD), bipolar disorder, type I (BD-I), and MDD with alcohol use disorder (MDAUD).

METHODS

We conducted a 6-month open-label study, involving 82 patients with DSM-5 Depressive Episode. Of these, 41 had diagnosis of MDD, 20 BD-I, and 21 MDAUD. All patients received standard drug treatment and add-on dTMS over the bilateral DLPFC with left prevalence for four weeks, with five sessions in each week. We rated mood state with the Hamilton Depression Rating Scale (HDRS) at baseline, one-month, and six-month follow-up visits.

RESULTS

Mean total HDRS scores dropped from 22.8 (SD = 5.9) at baseline to 10.4 (SD = 3.6) at 1 month, to 10.0 (SD = 4.5) at 6 months, while response/remission were 70.73% (N = 58) and 19.51% (N = 16) at 1 month and 76.83% (N = 63) and 32.93% (27) at 6 months, respectively, with no between-group differences. No patient experienced any side effects.

CONCLUSIONS

High-frequency DLPFC dTMS was well tolerated and did not significantly differ on improvement of depression in MDD, BD-I, and MDAUD.

Free Interval Duration: Clinical Evidence of the Primary Role of Excitement in Bipolar Disorder

BACKGROUND

Cyclicity is the essential feature of Bipolar disorder, but the effect of different cycle patterns on the clinical features is poorly understood. Moreover, no studies investigated the relationship between mania and depression inside the manic-depressive cycle.

OBJECTIVE

The aim of this study is to verify the presence of a relationship between the manic and the depressive phase during the course of bipolar disorder.

METHOD

160 consecutive patients with BD type I were recruited and followed for a mean period of 10 years. During the follow-up period, four types of euthymic phases were collected: free intervals present between a depressive and a manic/hypomanic episode (D-M); free intervals present between a manic/hypomanic and a depressive episode (M-D); free intervals present between two depressive episodes (D-D); free intervals present between two manic/hypomanic episodes (M-M). One-way ANOVA using the groups as independent variable and the duration of the free intervals as dependent variables was used. Furthermore, ANOVA was followed by Fisher's Protected Least Significant Difference post-hoc test to measure between-group differences.

RESULTS

M-D-free interval phases were shorter than D-M-free intervals. M-D intervals were the shortest ones, the D-D and D-M did not differ, and the M-M were the longest.

CONCLUSION

The strict temporal link between manic and depressive phases supports the idea that the manic-depressive cycle usually begins with a manic episode, and that the subsequent depression is often the consequence of subsiding mania.

How to Use the H1 Deep Transcranial Magnetic Stimulation Coil for Conditions Other than Depression

Deep transcranial magnetic stimulation (dTMS) is a relatively new technique that uses different coils for the treatment of different neuropathologies. The coils are made of soft copper windings in multiple planes that lie adjacent to the skull. They are located within a special helmet so that their magnetic fields combine and improve depth penetration. The H1 dTMS coil is designed to stimulate bilateral prefrontal cortices with greater effective stimulation over the left than the right. By positioning the left side of the coil close to the left dorsolateral prefrontal cortex (DLPFC), the H1 coil was used in a multisite study, leading to FDA approval for treatment-resistant depression. In this same position, the H1 coil was also explored as a possible treatment for negative symptoms of schizophrenia, bipolar depression, and migraine. When moved to different positions over the subject's skull, the H1 coil was also explored as a possible treatment for other conditions. Such manipulation of the H1 coil was demonstrated for PTSD and alcohol dependence by positioning it over the medial prefrontal cortex (mPFC), for anxiety by positioning it over the right prefrontal cortex (rPFC), for auditory hallucinations and tinnitus by positioning it over the temporoparietal junction (TPJ), and for Parkinson's and fatigue from multiple sclerosis (MS) by positioning it over the motor cortex (MC) and PFC. Corresponding electrical field diagrams measured with an oscilloscope through a saline-filled head are included.

Deep transcranial magnetic stimulation (dTMS) - beyond depression

INTRODUCTION

Deep transcranial magnetic stimulation (dTMS) utilizes different H-coils to study and treat a variety of psychiatric and neurological conditions with identifiable brain targets. The availability of this technology is dramatically changing the practice of psychiatry and neurology as it provides a safe and effective way to treat even drug-resistant patients. However, up until now, no effort was made to summarize the different types of H-coils that are available, and the conditions for which they were tested. Areas covered: Here we assembled all peer reviewed publication that used one of the H-coils, together with illustrations of the effective field they generate within the brain. Currently, the technology has FDA clearance for depression and European clearance for additional disorders, and multi-center trials are exploring its safety and effectiveness for OCD, PTSD, bipolar depression and nicotine addiction. Expert commentary: Taken together with positive results in smaller scale experiments, dTMS coils represent a non-invasive way to manipulate pathological activity in different brain structures and circuits. Advances in stimulation and imaging methods can now lead to efficacious and logical treatments. This should reduce the stigma associated with mental disorders, and improve access to psychiatric treatment.

Cognitive functioning and deep transcranial magnetic stimulation (DTMS) in major psychiatric disorders: A systematic review

Deep transcranial magnetic stimulation (DTMS) is a non-invasive brain stimulation method mostly utilised in the treatment of major depression. The aim of the current study was to systematically review the literature on the cognitive effects of DTMS applied with the H-coil system in major psychiatric disorders. Following a literature search in PsycInfo and PubMed (any time to December 2015), 13 out of 32 studies on DTMS and cognitive functioning were included in the current review. Three studies included 38 healthy participants, eight studies included 158 unipolar or bipolar depression patients and two studies included 45 schizophrenia patients. Low-frequency DTMS (1-3 sessions) had little effect on cognitive functioning in healthy participants. The most consistent cognitive and clinical improvements were reported in the short-term (after 20 daily sessions of high-frequency DTMS with H1-coil) in studies with major depression patients. There was also a trend towards a short-term cognitive and clinical improvement in studies with schizophrenia patients. High-frequency DTMS might improve cognitive functioning and alleviate clinical symptoms in the short-term, particularly in major depression. However, this conclusion is based on data from mostly uncontrolled, open-label studies with patients receiving concurrent antidepressants or antipsychotics. Randomised, sham-controlled trials are needed to investigate the magnitude of the cognitive outcomes of DTMS in the short-term and beyond the daily stimulation phase in major psychiatric disorders.

Update on Neuromodulation for Treatment-Resistant Depression

About 30% of patients suffering from a major depressive disorder do not respond sufficiently to established pharmacological, psychotherapeutic, or somatic treatments. Advances in technology and emerging knowledge about the dysfunctional brain circuits underlying depression have led to the development of different neuromodulation techniques. The aim of the present review is to give an update on noninvasive techniques, such as electroconvulsive therapy (ECT), magnetic seizure therapy (MST), transcranial magnetic stimulation (TMS), and invasive techniques requiring brain surgery, such as vagus nerve stimulation (VNS) and deep brain stimulation (DBS). First, the clinical relevance for therapy-resistant depression, including the current level of evidence, are presented. Neuroethics is concerned with the ethical, legal and social policy implications of neuroscience. A second focus of the review is the application of fundamental ethical principles, such as patient autonomy, patient well-being and justice to neuromodulation therapies. Due to reduced availability and lacking long-term efficacy data, most patients with treatment-resistant depression face a trial-and-error approach to therapeutics. This contravenes the ethical criteria of patient autonomy and justice. In order to raise the level of evidence, financial support of long-term studies, including large samples and randomized control trials, are necessary.

Deep transcranial magnetic stimulation (DTMS) in the treatment of major depression: An exploratory systematic review and meta-analysis

BACKGROUND

Deep transcranial magnetic stimulation (DTMS) is a relatively new, non-invasive method of stimulating larger and, presumably, deeper brain regions. The current study investigated if DTMS delivered with H-coils has acute antidepressant effects in major depression using a systematic literature review and a quantitative meta-analysis.

METHODS

Seventeen studies on 'DTMS or H-coil' and 'depression' were identified on Medline, PsycInfo, and Google Scholar (until November 2014). Data from nine open-label studies were meta-analysed using a random-effects model with inverse-variance weights. The outcome measures were the standardised paired mean difference (Cohen's d) in depression scores on Hamilton Depression Rating Scale (HDRS), response, remission, and dropout rates after acute DTMS treatment compared to baseline.

RESULTS

There was a large antidepressant effect after 20 acute, high-frequency DTMS sessions compared to baseline according to HDRS change scores (overall mean weighted d=2.04, 95% confidence interval: 1.53-2.55; nine studies; 150 patients). Overall weighted response, remission, and dropout rates were 60%, 29%, and 18% respectively. HDRS change scores and response rates tended to be higher in four studies with 68 patients on concurrent antidepressants compared to two studies with 26 patients who received DTMS as a monotherapy.

LIMITATIONS

These results are based on data from a low number of open-label studies.

CONCLUSION

High-frequency DTMS appears to have acute antidepressant effects after 20 sessions in mostly unipolar and treatment-resistant patients. Concurrent treatment with antidepressants might enhance the efficacy of DTMS.

Maintenance Deep Transcranial Magnetic Stimulation Sessions are Associated with Reduced Depressive Relapses in Patients with Unipolar or Bipolar Depression

Introduction: Deep transcranial magnetic stimulation (dTMS) is a new form of TMS allowing safe stimulation of deep brain regions. The objective of this preliminary study was to assess the role of dTMS maintenance sessions in protecting patients with bipolar disorder (BD) or recurrent major depressive disorder (MDD) from developing depressive or manic relapses in a 12-month follow-up period.

Methods: Twenty-four drug-resistant patients with a current depressive episode and a diagnosis of MDD or BD have been enrolled in the study. All the participants underwent daily dTMS sessions for 4 weeks. One group (maintenance – M group) received additional maintenance dTMS sessions weekly or twice a week.

Results: After the first dTMS cycle, a significant reduction of Hamilton Depression Rating Scale (HDRS) scores was observed in all participants. Subsequently, the HDRS mean scores did not significantly change over time in the M group, while it significantly increased in the non-M-group after 6 and 12 months.

Discussion: This study confirms previous evidence of a positive therapeutic effect of dTMS on depressive symptoms and suggests that, after recovery from acute episodes, maintenance dTMS sessions may be helpful in maintaining euthymia in a 12-month follow-up period.

Efficacy and safety of deep transcranial magnetic stimulation for major depression: a prospective multicenter randomized controlled trial

Major depressive disorder (MDD) is a prevalent and disabling condition, and many patients do not respond to available treatments. Deep transcranial magnetic stimulation (dTMS) is a new technology allowing non-surgical stimulation of relatively deep brain areas. This is the first double-blind randomized controlled multicenter study evaluating the efficacy and safety of dTMS in MDD. We recruited 212 MDD outpatients, aged 22-68 years, who had either failed one to four antidepressant trials or not tolerated at least two antidepressant treatments during the current episode. They were randomly assigned to monotherapy with active or sham dTMS. Twenty sessions of dTMS (18 Hz over the prefrontal cortex) were applied during 4 weeks acutely, and then biweekly for 12 weeks. Primary and secondary efficacy endpoints were the change in the Hamilton Depression Rating Scale (HDRS-21) score and response/remission rates at week 5, respectively. dTMS induced a 6.39 point improvement in HDRS-21 scores, while a 3.28 point improvement was observed in the sham group (p=0.008), resulting in a 0.76 effect size. Response and remission rates were higher in the dTMS than in the sham group (response: 38.4 vs. 21.4%, p=0.013; remission: 32.6 vs. 14.6%, p=0.005). These differences between active and sham treatment were stable during the 12-week maintenance phase. dTMS was associated with few and minor side effects apart from one seizure in a patient where a protocol violation occurred. These results suggest that dTMS constitutes a novel intervention in MDD, which is efficacious and safe in patients not responding to antidepressant medications, and whose effect remains stable over 3 months of maintenance treatment.

A brain centred view of psychiatric comorbidity in tinnitus: from otology to hodology

Introduction. Comorbid psychiatric disorders are frequent among patients affected by tinnitus. There are mutual clinical influences between tinnitus and psychiatric disorders, as well as neurobiological relations based on partially overlapping hodological and neuroplastic phenomena. The aim of the present paper is to review the evidence of alterations in brain networks underlying tinnitus physiopathology and to discuss them in light of the current knowledge of the neurobiology of psychiatric disorders. Methods. Relevant literature was identified through a search on Medline and PubMed; search terms included tinnitus, brain, plasticity, cortex, network, and pathways. Results. Tinnitus phenomenon results from systemic-neurootological triggers followed by neuronal remapping within several auditory and nonauditory pathways. Plastic reorganization and white matter alterations within limbic system, arcuate fasciculus, insula, salience network, dorsolateral prefrontal cortex, auditory pathways, ffrontocortical, and thalamocortical networks are discussed. Discussion. Several overlapping brain network alterations do exist between tinnitus and psychiatric disorders. Tinnitus, initially related to a clinicoanatomical approach based on a cortical localizationism, could be better explained by an holistic or associationist approach considering psychic functions and tinnitus as emergent properties of partially overlapping large-scale neural networks.

Coil design considerations for deep transcranial magnetic stimulation

OBJECTIVES

To explore the field characteristics and design tradeoffs of coils for deep transcranial magnetic stimulation (dTMS).

METHODS

We simulated parametrically two dTMS coil designs on a spherical head model using the finite element method, and compare them with five commercial TMS coils, including two that are FDA approved for the treatment of depression (ferromagnetic-core figure-8 and H1 coil).

RESULTS

Smaller coils have a focality advantage over larger coils; however, this advantage diminishes with increasing target depth. Smaller coils have the disadvantage of producing stronger field in the superficial cortex and requiring more energy. When the coil dimensions are large relative to the head size, the electric field decay in depth becomes linear, indicating that, at best, the electric field attenuation is directly proportional to the depth of the target. Ferromagnetic cores improve electrical efficiency for targeting superficial brain areas; however magnetic saturation reduces the effectiveness of the core for deeper targets, especially for highly focal coils. Distancing winding segments from the head, as in the H1 coil, increases the required stimulation energy.

CONCLUSIONS

Among standard commercial coils, the double cone coil offers high energy efficiency and balance between stimulated volume and superficial field strength. Direct TMS of targets at depths of ~4 cm or more results in superficial stimulation strength that exceeds the upper limit in current rTMS safety guidelines. Approaching depths of ~6 cm is almost certainly unsafe considering the excessive superficial stimulation strength and activated brain volume.

SIGNIFICANCE

Coil design limitations and tradeoffs are important for rational and safe exploration of dTMS.

Efficacy of add-on deep transcranial magnetic stimulation in comorbid alcohol dependence and dysthymic disorder: three case reports

BACKGROUND

Craving for alcohol is associated with abnormal activation in the dorsolateral prefrontal cortex. Deep transcranial magnetic stimulation (dTMS) has shown promise in the treatment of depression. There are few treatment options for treatment-resistant dysthymic disorder comorbid with alcohol use disorder.

OBJECTIVE

To investigate the possible anticraving efficacy of bilateral dorsolateral prefrontal cortex high-frequency dTMS in 3 patients with comorbid long-term DSM-IV-TR dysthymic disorder and alcohol use disorder.

METHOD

Three patients with alcohol use disorder with dysthymic disorder in their detoxification phase (abstaining for > 1 month) underwent twenty 20-minute sessions of 20 Hz dTMS over the dorsolateral prefrontal cortex over 28 days between 2011 and 2012. Alcohol craving was rated with the Obsessive Compulsive Drinking Scale and depressive symptoms with the Hamilton Depression Rating Scale.

RESULTS

All 3 patients responded unsatisfactorily to initial intravenous antidepressant and antianxiety combinations but responded after 10 dTMS sessions, improving on both anxiety-depressive symptoms and craving. This improvement enabled us to reduce antidepressant dosages after dTMS cycle completion.

DISCUSSION

High-frequency bilateral dorsolateral prefrontal cortex dTMS with left prevalence was found to produce significant anticraving effects in alcohol use disorder comorbid with dysthymic disorder. The potential of dTMS for reducing craving in patients with substance use disorder deserves to be further investigated.