Subcallosal cingulate deep brain stimulation for treatment-refractory anorexia nervosa: a phase 1 pilot trial

Pain-Insomnia-Depression Syndrome: Triangular Relationships, Pathobiological Correlations, Current Treatment Modalities, and Future Direction

Pain-insomnia-depression syndrome (PIDS) is a complex triad of chronic pain, insomnia, and depression that has profound effects on an individual's quality of life and mental health. The pathobiological context of PIDS involves complex neurobiological and physiological mechanisms, including alterations in neurotransmitter systems and impaired pain processing pathways. The first-line therapeutic approaches for the treatment of chronic pain, depression, and insomnia are a combination of pharmacological and non-pharmacological therapies. In cases where patients do not respond adequately to these treatments, additional interventions such as deep brain stimulation (DBS) may be required. Despite advances in understanding and treatment, there are still gaps in knowledge that need to be addressed. To improve our understanding, future research should focus on conducting longitudinal studies to uncover temporal associations, identify biomarkers and genetic markers associated with PIDS, examine the influence of psychosocial factors on treatment responses, and develop innovative interventions that address the complex nature of PIDS. The aim of this study is to provide a comprehensive overview of these components and to discuss their underlying pathobiological relationships.

A Novel Closed-Loop Electrical Brain Stimulation Device Featuring Wireless Low-Energy Ultrasound Power and Communication

OBJECTIVES

This study aimed to indicate the feasibility of a prototype electrical neuromodulation system using a closed-loop energy-efficient ultrasound-based mechanism for communication, data transmission, and recharging.

MATERIALS AND METHODS

Closed-loop deep brain stimulation (DBS) prototypes were designed and fabricated with ultrasonic wideband (UsWB) communication technology and miniaturized custom electronics. Two devices were implanted short term in anesthetized Göttingen minipigs (N = 2). Targeting was performed using preoperative magnetic resonance imaging, and locations were confirmed postoperatively by computerized tomography. DBS systems were tested over a wide range of stimulation settings to mimic minimal, typical, and/or aggressive clinical settings, and evaluated for their ability to transmit data through scalp tissue and to recharge the DBS system using UsWB.

RESULTS

Stimulation, communication, reprogramming, and recharging protocols were successfully achieved in both subjects for amplitude (1V-6V), frequency (50-250 Hz), and pulse width (60-200 μs) settings and maintained for ≥six hours. The precision of pulse settings was verified with <5% error. Communication rates of 64 kbit/s with an error rate of 0.05% were shown, with no meaningful throughput degradation observed. Time to recharge to 80% capacity was <9 minutes. Two DBS systems also were implanted in the second test animal, and independent bilateral stimulation was successfully shown.

CONCLUSIONS

The system performed at clinically relevant implant depths and settings. Independent bilateral stimulation for the duration of the study with a 4F energy storage and full rapid recharge were achieved. Continuous function extrapolates to six days of continuous stimulation in future design iterations implementing application specific integrated circuit level efficiency and 15F storage capacitance. UsWB increases energy efficiency, reducing storage requirements and thereby enabling device miniaturization. The device can enable intelligent closed-loop stimulation, remote system monitoring, and optimization and can serve as a power/data gateway to interconnect the intrabody network with the Internet of Medical Things.

Severe enduring anorexia nervosa (SE-AN) treatment options and their effectiveness: a review of literature

INTRODUCTION

 For nearly 20% of patients diagnosed with Anorexia Nervosa (AN), the eating disorder (ED) is prolonged and becomes long-lasting. It has been reported that patients diagnosed with Severe Enduring Anorexia Nervosa (SE-AN) have worse ED symptoms, higher rates of lifetime hospitalization, and lower psychosocial well-being compared to patients with shorter disease duration.

OBJECTIVES

 This review aims to describe the treatments proposed to date and their effectiveness on SE-AN-related outcomes.

METHODS

 We conducted a PubMed search for studies addressing the issue of treatment approach to SE-AN adults, that were published between 2003 and 2023, peer-reviewed, written in the English language, and available in full-text. Next, we inductively created relevant macro-themes by synthesizing the data from the included articles.

RESULTS

 Of 251 PubMed studies, 25 articles were considered for data extraction, all published between 2003 and 2022. We identified three macro-themes. The first macro-theme, "Psychotherapy", mostly takes into consideration treatment effectiveness of cognitive behavioral therapy (CBT). Various reports determined its greater effectiveness compared to Specialist Supportive Clinical Management (SSCM), and one study proved that outpatient CBT is a valid alternative to hospitalization. The second one involves "Pharmacological Treatments". Research on dronabinol, a synthetic orexigenic cannabinoid, antipsychotics (in particular, olanzapine and haloperidol), and ketamine showed some mixed results regarding the often-complementary areas of weight gain and improvement in ED-related symptoms. Regarding the third macro-theme, "Brain Stimulation Therapies," such as Repetitive Transcranial Magnetic Stimulation (rTMS) and Deep Brain Stimulation (DBS), we found promising results in improving ED-related psychological traits (such as mood and anxiety), affective regulation, and quality of life. However, we have observed divergent results regarding outcome measures such as BMI and weight gain.

CONCLUSIONS

 SE-AN patients are predicted to encounter both medical complications and psychological distress of increasing severity that will inevitably affect their quality of life; to our knowledge, research evidence on treatment options for SE-AN remains limited, and the methodological quality of studies is generally low. These findings denote the need to focus future research efforts on effective treatment strategies specific to long-lasting EDs.

Neurosurgical neuromodulation therapy for psychiatric disorders

Psychiatric disorders are among the leading contributors to global disease burden and disability. A significant portion of patients with psychiatric disorders remain treatment-refractory to best available therapy. With insights from the neurocircuitry of psychiatric disorders and extensive experience of neuromodulation with deep brain stimulation (DBS) in movement disorders, DBS is increasingly being considered to modulate the neural network in psychiatric disorders. Currently, obsessive-compulsive disorder (OCD) is the only U.S. FDA (United States Food and Drug Administration) approved DBS indication for psychiatric disorders. Medically refractory depression, addiction, and other psychiatric disorders are being explored for DBS neuromodulation. Studies evaluating DBS for psychiatric disorders are promising but lack larger, controlled studies. This paper presents a brief review and the current state of DBS and other neurosurgical neuromodulation therapies for OCD and other psychiatric disorders. We also present a brief review of MR-guided Focused Ultrasound (MRgFUS), a novel form of neurosurgical neuromodulation, which can target deep subcortical structures similar to DBS, but in a noninvasive fashion. Early experiences of neurosurgical neuromodulation therapies, including MRgFUS neuromodulation are encouraging in psychiatric disorders; however, they remain investigational. Currently, DBS and VNS are the only FDA approved neurosurgical neuromodulation options in properly selected cases of OCD and depression, respectively.

Prefrontal network engagement by deep brain stimulation in limbic hubs

Prefrontal circuits in the human brain play an important role in cognitive and affective processing. Neuromodulation therapies delivered to certain key hubs within these circuits are being used with increasing frequency to treat a host of neuropsychiatric disorders. However, the detailed neurophysiological effects of stimulation to these hubs are largely unknown. Here, we performed intracranial recordings across prefrontal networks while delivering electrical stimulation to two well-established white matter hubs involved in cognitive regulation and depression: the subcallosal cingulate (SCC) and ventral capsule/ventral striatum (VC/VS). We demonstrate a shared frontotemporal circuit consisting of the ventromedial prefrontal cortex, amygdala, and lateral orbitofrontal cortex where gamma oscillations are differentially modulated by stimulation target. Additionally, we found participant-specific responses to stimulation in the dorsal anterior cingulate cortex and demonstrate the capacity for further tuning of neural activity using current-steered stimulation. Our findings indicate a potential neurophysiological mechanism for the dissociable therapeutic effects seen across the SCC and VC/VS targets for psychiatric neuromodulation and our results lay the groundwork for personalized, network-guided neurostimulation therapy.

Local neuroanatomical and tract-based proxies of optimal subcallosal cingulate deep brain stimulation

BACKGROUND

Deep brain stimulation of the subcallosal cingulate area (SCC-DBS) is a promising neuromodulatory therapy for treatment-resistant depression (TRD). Biomarkers of optimal target engagement are needed to guide surgical targeting and stimulation parameter selection and to reduce variance in clinical outcome.

OBJECTIVE/HYPOTHESIS

We aimed to characterize the relationship between stimulation location, white matter tract engagement, and clinical outcome in a large (n = 60) TRD cohort treated with SCC-DBS. A smaller cohort (n = 22) of SCC-DBS patients with differing primary indications (bipolar disorder/anorexia nervosa) was utilized as an out-of-sample validation cohort.

METHODS

Volumes of tissue activated (VTAs) were constructed in standard space using high-resolution structural MRI and individual stimulation parameters. VTA-based probabilistic stimulation maps (PSMs) were generated to elucidate voxelwise spatial patterns of efficacious stimulation. A whole-brain tractogram derived from Human Connectome Project diffusion-weighted MRI data was seeded with VTA pairs, and white matter streamlines whose overlap with VTAs related to outcome ('discriminative' streamlines; Puncorrected < 0.05) were identified using t-tests. Linear modelling was used to interrogate the potential clinical relevance of VTA overlap with specific structures.

RESULTS

PSMs varied by hemisphere: high-value left-sided voxels were located more anterosuperiorly and squarely in the lateral white matter, while the equivalent right-sided voxels fell more posteroinferiorly and involved a greater proportion of grey matter. Positive discriminative streamlines localized to the bilateral (but primarily left) cingulum bundle, forceps minor/rostrum of corpus callosum, and bilateral uncinate fasciculus. Conversely, negative discriminative streamlines mostly belonged to the right cingulum bundle and bilateral uncinate fasciculus. The best performing linear model, which utilized information about VTA volume overlap with each of the positive discriminative streamline bundles as well as the negative discriminative elements of the right cingulum bundle, explained significant variance in clinical improvement in the primary TRD cohort (R = 0.46, P < 0.001) and survived repeated 10-fold cross-validation (R = 0.50, P = 0.040). This model was also able to predict outcome in the out-of-sample validation cohort (R = 0.43, P = 0.047).

CONCLUSION(S)

These findings reinforce prior indications of the importance of white matter engagement to SCC-DBS treatment success while providing new insights that could inform surgical targeting and stimulation parameter selection decisions.

Neural effects of deep brain stimulation on reward and loss anticipation and food viewing in anorexia nervosa: a pilot study

BACKGROUND

Anorexia nervosa (AN) is a severe and life-threatening psychiatric disorder. Initial studies on deep brain stimulation (DBS) in severe, treatment-refractory AN have shown clinical effects. However, the working mechanisms of DBS in AN remain largely unknown. Here, we used a task-based functional MRI approach to understand the pathophysiology of AN.

METHODS

We performed functional MRI on four AN patients that participated in a pilot study on the efficacy, safety, and functional effects of DBS targeted at the ventral limb of the capsula interna (vALIC). The patients and six gender-matched healthy controls (HC) were investigated at three different time points. We used an adapted version of the monetary incentive delay task to probe generic reward processing in patients and controls, and a food-specific task in patients only.

RESULTS

At baseline, no significant differences for reward anticipation were found between AN and HC. Significant group (AN and HC) by time (pre- and post-DBS) interactions were found in the right precuneus, right putamen, right ventral and medial orbitofrontal cortex (mOFC). No significant interactions were found in the food viewing task, neither between the conditions high-calorie and low-calorie food images nor between the different time points. This could possibly be due to the small sample size and the lack of a control group.

CONCLUSION

The results showed a difference in the response of reward-related brain areas post-DBS. This supports the hypotheses that the reward circuitry is involved in the pathogenesis of AN and that DBS affects responsivity of reward-related brain areas. Trial registration Registered in the Netherlands Trial Register ( https://www.trialregister.nl/trial/3322 ): NL3322 (NTR3469).

Pharmacotherapy, alternative and adjunctive therapies for eating disorders: findings from a rapid review

BACKGROUND

The current review broadly summarises the evidence base for pharmacotherapies and adjunctive and alternative therapies in the treatment of eating disorders and disordered eating.

METHODS

This paper forms part of a Rapid Review series examining the evidence base in the field of eating disorders. This was conducted to inform the Australian National Eating Disorder Research and Translation Strategy 2021-2030. ScienceDirect, PubMed and Ovid/Medline were searched for included studies published between 2009 and 2021 in English. High-level evidence such as meta-analyses, large population studies and randomised control trials were prioritised, and grey literature excluded. Data from included studies relating to pharmacotherapy, and to adjunctive and alternative therapies in eating disorders, were synthesised and disseminated in the current review.

RESULTS

A total of 121 studies were identified, relating to pharmacotherapy (n = 90), adjunctive therapies (n = 21) and alternative therapies (n = 22). Some of the identified studies involved combinations of the above (e.g. adjunctive pharmacotherapy). Evidence of efficacy of interventions across all three categories was very limited with few relevant high quality clinical trials. There was a particular scarcity of evidence around effective treatments for anorexia nervosa (AN). With treatment of bulimia nervosa (BN), fluoxetine has exhibited some efficacy leading to regulatory approval in some countries. With binge eating disorder (BED), recent evidence supports the use of lisdexamfetamine. Neurostimulation interventions show some emerging efficacy in the treatment of AN, BN and BED but some, such as deep brain stimulation can be highly invasive.

CONCLUSION

Despite widespread use of medications, this Rapid Review has identified a lack of effective medications and adjunctive and alternative therapies in the treatment of EDs. An intensification of high-quality clinical trial activity and drug discovery innovation are required to better assist patients suffering from EDs.

Therapeutic uses of psychedelics for eating disorders and body dysmorphic disorder

BACKGROUND

Clinical use of psychedelics has gained considerable attention, with promising benefits across a range of mental disorders. Current pharmacological and psychotherapeutic treatments for body dysmorphic disorder (BDD) and eating disorders (EDs) have limited efficacy. As such, other treatment options such as psychedelic-assisted therapies are being explored in these clinical groups.

AIMS

This systematic review evaluates evidence related to the therapeutic potential of psychedelics in individuals diagnosed with BDD and EDs.

METHODS

Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we conducted a systematic review of all study designs published to the end of February 2022 that identified changes in ED/BDD symptom severity from psychedelics using validated measures to assess symptom changes.

RESULTS

Our search detected a total of 372 studies, of which five met inclusion criteria (two exploratory studies, two case reports, and one prospective study). These were included in the data evaluation. Effects of psychedelics on BDD and various ED symptoms were identified mostly through thematic analyses and self-reports.

CONCLUSIONS

Our findings highlight that more research is needed to determine the safety and efficacy of psychedelics in BDD and EDs and we suggest avenues for future exploration.

Deep brain stimulation of the subgenual cingulum and uncinate fasciculus for the treatment of posttraumatic stress disorder

Deep brain stimulation (DBS) has been investigated for neuropsychiatric disorders. In this phase 1 trial, we treated four posttraumatic stress disorder (PTSD) patients with DBS delivered to the subgenual cingulum and the uncinate fasciculus. In addition to validated clinical scales, patients underwent neuroimaging studies and psychophysiological assessments of fear conditioning, extinction, and recall. We show that the procedure is safe and potentially effective (55% reduction in Clinical Administered PTSD Scale scores). Posttreatment imaging data revealed metabolic activity changes in PTSD neurocircuits. During psychophysiological assessments, patients with PTSD had higher skin conductance responses when tested for recall compared to healthy controls. After DBS, this objectively measured variable was significantly reduced. Last, we found that a ratio between recall of extinguished and nonextinguished conditioned responses had a strong correlation with clinical outcome. As this variable was recorded at baseline, it may comprise a potential biomarker of treatment response.

Connectomic neuromodulation for Alzheimer's disease: A systematic review and meta-analysis of invasive and non-invasive techniques

Deep brain stimulation (DBS) and non-invasive neuromodulation are currently being investigated for treating network dysfunction in Alzheimer's Disease (AD). However, due to heterogeneity in techniques and targets, the cognitive outcome and brain network connectivity remain unknown. We performed a systematic review, meta-analysis, and normative functional connectivity to determine the cognitive outcome and brain networks of DBS and non-invasive neuromodulation in AD. PubMed, Embase, and Web of Science were searched using three concepts: dementia, brain connectome, and brain stimulation, with filters for English, human studies, and publication dates 1980-2021. Additional records from clinicaltrials.gov were added. Inclusion criteria were AD study with DBS or non-invasive neuromodulation and a cognitive outcome. Exclusion criteria were less than 3-months follow-up, severe dementia, and focused ultrasound intervention. Bias was assessed using Centre for Evidence-Based Medicine levels of evidence. We performed meta-analysis, with subgroup analysis based on type and age at neuromodulation. To determine the patterns of neuromodulation-induced brain network activation, we performed normative functional connectivity using rsfMRI of 1000 healthy subjects. Six studies, with 242 AD patients, met inclusion criteria. On fixed-effect meta-analysis, non-invasive neuromodulation favored baseline, with effect size -0.40(95% [CI], -0.73, -0.06, p = 0.02), while that of DBS was 0.11(95% [CI] -0.34, 0.56, p = 0.63), in favor of DBS. In patients ≥65 years old, DBS improved cognitive outcome, 0.95(95% [CI] 0.31, 1.58, p = 0.004), whereas in patients <65 years old baseline was favored, -0.17(95% [CI] -0.93, 0.58, p = 0.65). Functional connectivity regions were in the default mode (DMN), salience (SN), central executive (CEN) networks, and Papez circuit. The subgenual cingulate and anterior limb of internal capsule (ALIC) showed connectivity to all targets of neuromodulation. This meta-analysis provides level II evidence of a difference in response of AD patients to DBS, based on age at intervention. Brain stimulation in AD may modulate DMN, SN, CEN, and Papez circuit, with the subgenual cingulate and ALIC as potential targets.

Deep brain stimulation of the nucleus accumbens in the treatment of severe alcohol use disorder: a phase I pilot trial

Alcohol use disorder (AUD) is a highly prevalent, often refractory, medical illness. The symptoms of AUD are driven by dysfunction in several neurocircuits centered on the nucleus accumbens (NAc). Case reports and animal studies suggest NAc-DBS may be an effective harm-reduction treatment in severe AUD. Six patients with severe, refractory AUD underwent NAc-DBS. Safety metrics and clinical outcomes were recorded. Positron emission tomography (FDG-PET) was used to measure glucose metabolism in the NAc at baseline and 6 months. Functional magnetic resonance imaging (fMRI) was used to characterize postoperative changes in NAc functional connectivity to the rest of the brain, as well as NAc and dorsal striatal reactivity to alcoholic visual cues. This study was registered with ClinicalTrials.gov, NCT03660124. All patients experienced a reduction in craving. There was a significant reduction in alcohol consumption, alcohol-related compulsivity, and anxiety at 12 months. There was no significant change in depression. FDG-PET analysis demonstrated reduced NAc metabolism by 6 months, which correlated with improvements in compulsive drinking behaviors. Clinical improvement correlated with reduced functional connectivity between the NAc and the visual association cortex. Active DBS was associated with reduced activation of the dorsal striatum during passive viewing of alcohol-containing pictures. NAc-DBS is feasible and safe in patients with severe, otherwise refractory AUD. It is associated with a reduction in cravings and addictive behavior. A potential mechanism underlying this process is a down-regulation of the NAc, a disruption of its functional connectivity to the visual association cortex, and interference of cue-elicited dorsal striatum reactivity. Trial Registration NCT03660124 ( www.clinicaltrials.gov ).

Efficacy and safety of deep brain stimulation for treatment-refractory anorexia nervosa: a systematic review and meta-analysis

BACKGROUND

Several pioneering studies investigated deep brain stimulation (DBS) in treatment-refractory anorexia nervosa (AN) patients, but overall effects remain yet unclear. Aim of this study was to obtain estimates of efficacy of DBS in AN-patients using meta-analysis.

METHODS

We searched three electronic databases until 1st of November 2021, using terms related to DBS and AN. We included trials that investigated the clinical effects of DBS in AN-patients. We obtained data including psychiatric comorbidities, medication use, DBS target, and study duration. Primary outcome was Body Mass Index (BMI), secondary outcome was quality of life, and the severity of psychiatric symptoms, including eating disorder, obsessive-compulsive, depressive, and anxiety symptoms. We assessed the risk of bias using the ROBINS-I tool.

RESULTS

Four studies were included for meta-analysis, with a total of 56 patients with treatment-refractory AN. Follow-up ranged from 6-24 months. Random effects meta-analysis showed a significant increase in BMI following DBS, with a large effect size (Hedges's g = 1 ∙ 13; 95% CI = 0 ∙ 80 to 1 ∙ 46; Z-value = 6 ∙ 75; P < 0 ∙ 001), without heterogeneity (I²= 0 ∙ 00, P = 0 ∙ 901). Random effects meta-analysis also showed a significant increase in quality of life (Hedges's g = 0 ∙ 86; 95% CI = 0 ∙ 44 to 1 ∙ 28; Z-value = 4 ∙ 01, P < 0 ∙ 001). Furthermore, DBS decreased the severity of psychiatric symptoms (Hedges's g = 0 ∙ 89; 95% CI = 0 ∙ 57 to 1 ∙ 21; Z-value = 5 ∙ 47; P < 0 ∙ 001, I²= 4 ∙ 29, P = 0 ∙ 371).

DISCUSSION

In this first meta-analysis, DBS showed statistically large beneficial effects on weight restoration, quality of life, and reduction of psychiatric symptoms in patients with treatment-refractory AN. These outcomes call for more extensive naturalistic studies to determine the clinical relevance for functional recovery. This study is preregistered in PROSPERO,CRD42022295712.

A meta-analytic investigation of grey matter differences in anorexia nervosa and autism spectrum disorder

Recent research reports Anorexia Nervosa (AN) to be highly dependent upon neurobiological function. Some behaviours, particularly concerning food selectivity are found in populations with both Autism Spectrum Disorder (ASD) and AN, and there is a proportionally elevated number of anorexic patients exhibiting symptoms of ASD. We performed a systematic review of structural MRI literature with the aim of identifying common structural neural correlates common to both AN and ASD. Across 46 ASD publications, a meta‐analysis of volumetric differences between ASD and healthy controls revealed no consistently affected brain regions. Meta‐analysis of 23 AN publications revealed increased volume within the orbitofrontal cortex and medial temporal lobe, and adult‐only AN literature revealed differences within the genu of the anterior cingulate cortex. The changes are consistent with alterations in flexible reward‐related learning and episodic memory reported in neuropsychological studies. There was no structural overlap between ASD and AN. Findings suggest no consistent neuroanatomical abnormality associated with ASD, and evidence is lacking to suggest that reported behavioural similarities between those with AN and ASD are due to neuroanatomical structural similarities.

Findings related to neuroanatomical structure in AN/ASD demonstrate overlap and require revisiting.

Meta‐analytic findings show structural increase/decrease versus healthy controls (LPFC/MTL/OFC) in AN, but no clusters found in ASD.

The neuroanatomy associated with ASD is inconsistent, but findings in AN reflect condition‐related impairment in executive function and sociocognitive behaviours.

Probing responses to deep brain stimulation with functional magnetic resonance imaging

BACKGROUND

Deep brain stimulation (DBS) is an established treatment for certain movement disorders and has additionally shown promise for various psychiatric, cognitive, and seizure disorders. However, the mechanisms through which stimulation exerts therapeutic effects are incompletely understood. A technique that may help to address this knowledge gap is functional magnetic resonance imaging (fMRI). This is a non-invasive imaging tool which permits the observation of DBS effects in vivo.

OBJECTIVE

The objective of this review was to provide a comprehensive overview of studies in which fMRI during active DBS was performed, including studied disorders, stimulated brain regions, experimental designs, and the insights gleaned from stimulation-evoked fMRI responses.

METHODS

We conducted a systematic review of published human studies in which fMRI was performed during active stimulation in DBS patients. The search was conducted using PubMED and MEDLINE.

RESULTS

The rate of fMRI DBS studies is increasing over time, with 37 studies identified overall. The median number of DBS patients per study was 10 (range = 1-67, interquartile range = 11). Studies examined fMRI responses in various disease cohorts, including Parkinson's disease (24 studies), essential tremor (3 studies), epilepsy (3 studies), obsessive-compulsive disorder (2 studies), pain (2 studies), Tourette syndrome (1 study), major depressive disorder, anorexia, and bipolar disorder (1 study), and dementia with Lewy bodies (1 study). The most commonly stimulated brain region was the subthalamic nucleus (24 studies). Studies showed that DBS modulates large-scale brain networks, and that stimulation-evoked fMRI responses are related to the site of stimulation, stimulation parameters, patient characteristics, and therapeutic outcomes. Finally, a number of studies proposed fMRI-based biomarkers for DBS treatment, highlighting ways in which fMRI could be used to confirm circuit engagement and refine DBS therapy.

CONCLUSION

A review of the literature reflects an exciting and expanding field, showing that the combination of DBS and fMRI represents a uniquely powerful tool for simultaneously manipulating and observing neural circuitry. Future work should focus on relatively understudied disease cohorts and stimulated regions, while focusing on the prospective validation of putative fMRI-based biomarkers.

Researchers’ Ethical Concerns About Using Adaptive Deep Brain Stimulation for Enhancement

The capacity of next-generation closed-loop or adaptive deep brain stimulation devices (aDBS) to read (measure neural activity) and write (stimulate brain regions or circuits) shows great potential to effectively manage movement, seizure, and psychiatric disorders, and also raises the possibility of using aDBS to electively (non-therapeutically) modulate mood, cognition, and prosociality. What separates aDBS from most neurotechnologies (e.g. transcranial stimulation) currently used for enhancement is that aDBS remains an invasive, surgically-implanted technology with a risk-benefit ratio significantly different when applied to diseased versus non-diseased individuals. Despite a large discourse about the ethics of enhancement, no empirical studies yet examine perspectives on enhancement from within the aDBS research community. We interviewed 23 aDBS researchers about their attitudes toward expanding aDBS use for enhancement. A thematic content analysis revealed that researchers share ethical concerns related to (1) safety and security; (2) enhancement as unnecessary, unnatural or aberrant; and (3) fairness, equality, and distributive justice. Most (70%) researchers felt that enhancement applications for DBS will eventually be technically feasible and that attempts to develop such applications for DBS are already happening (particularly for military purposes). However, researchers unanimously (100%) felt that DBS ideally should not be considered for enhancement until researchers better understand brain target localization and functioning. While many researchers acknowledged controversies highlighted by scholars and ethicists, such as potential impacts on personhood, authenticity, autonomy and privacy, their ethical concerns reflect considerations of both gravity and perceived near-term likelihood.

Role of deep brain stimulation in management of psychiatric disorders

Nowadays, most of patients affected by psychiatric disorders are successfully treated with conservative therapies. Still, a variable percentage of them demonstrate resistance to conventional treatments, and alternative methods can then be considered. During the last 20 years, there is a progressive interest in use of deep brain stimulation (DBS) in mental illnesses. It has become clear nowadays, that this modality may be effectively applied under specific indications in some patients with major depressive disorder, obsessive-compulsive disorder, anorexia nervosa and other eating disorders, Tourette syndrome, schizophrenia, substance use disorder, and even pathologically aggressive behavior. Despite the fact that the efficacy of neuromodulation with DBS, as well as of various lesional interventions, in cases of mental illnesses is still not fully established, there are several premises for wider applications of such "unclassical" psychiatric treatments in the future. Novel technologies of DBS, developments in non-invasive lesioning using stereotactic radiosurgery and transcranial magnetic resonance-guided focused ultrasound, and advances of neurophysiological and neuroimaging modalities may bolster further clinical applications of psychiatric neurosurgery, improve its results, and allow for individually selected treatment strategies tailored to specific needs of the patient.

Modern neurosurgical techniques for psychiatric disorders

Psychosurgery refers to an ensemble of more or less invasive techniques designed to reduce the burden caused by psychiatric diseases in patients who have failed to respond to conventional therapy. While most surgeries are designed to correct apparent anatomical abnormalities, no discrete cerebral anatomical lesion is evident in most psychiatric diseases amenable to invasive interventions. Finding the optimal surgical targets in mental illness is troublesome. In general, contemporary psychosurgical procedures can be classified into one of two primary modalities: lesioning and stimulation procedures. The first group is divided into (a) thermocoagulation and (b) stereotactic radiosurgery or recently introduced transcranial magnetic resonance-guided focused ultrasound, whereas stimulation techniques mainly include deep brain stimulation (DBS), cortical stimulation, and the vagus nerve stimulation. The most studied psychiatric diseases amenable to psychosurgical interventions are severe treatment-resistant major depressive disorder, obsessive-compulsive disorder, Tourette syndrome, anorexia nervosa, schizophrenia, and substance use disorder. Furthermore, modern neuroimaging techniques spurred the interest of clinicians to identify cerebral regions amenable to be manipulated to control psychiatric symptoms. On this way, the concept of a multi-nodal network need to be embraced, enticing the collaboration of psychiatrists, psychologists, neurologists and neurosurgeons participating in multidisciplinary groups, conducting well-designed clinical trials.

Neurosurgery and neuromodulation for anorexia nervosa in the 21st century: a systematic review of treatment outcomes

As current psychosocial and pharmacological interventions show limited efficacy in the treatment of anorexia nervosa (AN), interest in the potential value of neurosurgical intervention and neuromodulation in managing severe and enduring illness has grown. We conducted a systematic review of 20 trials of neurosurgical and neuromodulatory treatments for AN, including neurosurgical ablation, deep brain stimulation (DBS), repetitive transcranial magnetic stimulation (rTMS), and transcranial direct current stimulation (tDCS). Overall, there is evidence to support the role of stereotactic ablation and DBS in the treatment of AN. In contrast, results for rTMS and tDCS have been modest and generally more mixed. Neurosurgical treatment may offer important new avenues for the treatment of AN. Additional randomized clinical trials with comparable patient populations will be needed, in which change in affective, cognitive, and perceptual symptom phenomena, and interrogation of targeted circuits, pre- and post-intervention, are carefully documented.

Habenular Involvement in Response to Subcallosal Cingulate Deep Brain Stimulation for Depression

The habenula (Hb) is a small, evolutionarily conserved epithalamic structure implicated in functions such as reward and mood regulation. Prior imaging work suggests that Hb's structural and functional properties may relate to treatment response in depression and other mood disorders. We used multimodal MRI techniques to investigate the potential involvement of Hb in response to subcallosal cingulate area deep brain stimulation (SCC-DBS) for treatment-resistant mood disorders. Using an automated segmentation technique, we compared Hb volume at baseline and at a subsequent post-operative timepoint (4.4 ± 3.0 years after surgery) in a cohort of 32 patients who received SCC-DBS. Clinical response to treatment (≥50% decrease in HAMD-17 from baseline to 12 months post-operation) was significantly associated with longitudinal Hb volume change: responders tended to have increased Hb volume over time, while non-responders showed decreased Hb volume (t = 2.4, p = 0.021). We additionally used functional MRI (fMRI) in a subcohort of SCC-DBS patients (n = 12) to investigate immediate within-patient changes in Hb functional connectivity associated with SCC-DBS stimulation. Active DBS was significantly associated with increased Hb connectivity to several prefrontal and corticolimbic regions (TFCE-adjusted p _Bonferroni < 0.0001), many of which have been previously implicated in the neurocircuitry of depression. Taken together, our results suggest that Hb may play an important role in the antidepressant effect of SCC-DBS.

3 T MRI of rapid brain activity changes driven by subcallosal cingulate deep brain stimulation

Deep brain stimulation targeting the subcallosal cingulate area (SCC-DBS), a hub with multiple axonal projections, has shown therapeutic potential for treatment-resistant mood disorders. While SCC-DBS drives long-term metabolic changes in corticolimbic circuits, the brain areas that are directly modulated by electrical stimulation of this region are not known. We used 3.0 Tesla functional MRI to map the topography of acute brain changes produced by stimulation in an initial cohort of twelve patients with fully implanted SCC-DBS devices. Four additional SCC-DBS patients were also scanned and employed as a validation cohort. Participants underwent resting state scans (n=78 acquisitions overall) during i) inactive DBS; ii) clinically optimal active DBS; iii) suboptimal active DBS. All scans were acquired within a single MRI session, each separated by a 5-minute washout period. Analysis of the amplitude of low frequency fluctuations (ALFF) in each sequence indicated that clinically optimal SCC-DBS reduced spontaneous brain activity in several areas, including bilateral dorsal anterior cingulate cortex (dACC), posterior cingulate cortex (PCC), precuneus, and left inferior parietal lobule (pBonferroni<0.0001). Stimulation-induced dACC signal reduction correlated with immediate within-session mood fluctuations, was greater at optimal versus suboptimal settings, and related to local cingulum bundle engagement. Moreover, linear modelling showed that immediate changes in dACC, PCC, and precuneus activity could predict individual long-term antidepressant improvement. A model derived from the primary cohort that incorporated ALFF changes in these three areas (along with pre-operative symptom severity) explained 55% of the variance in clinical improvement in that cohort. The same model also explained 93% of the variance in the out-of-sample validation cohort. Additionally all three brain areas exhibited significant changes in functional connectivity between active and inactive DBS states (pBonferroni<0.01). These results provide insight into the network-level mechanisms of SCC-DBS and point towards potential acute biomarkers of clinical response that could help to optimize and personalize this therapy.

Neuromodulation in the Treatment of Alzheimer's Disease: Current and Emerging Approaches

Neuromodulation as a treatment strategy for psychiatric and neurological diseases has grown in popularity in recent years, with the approval of repetitive transcranial magnetic stimulation (rTMS) for the treatment of depression being one such example. These approaches offer new hope in the treatment of diseases that have proven largely intractable to traditional pharmacological approaches. For this reason, neuromodulation is increasingly being explored for the treatment of Alzheimer's disease. However, such approaches have variable, and, in many cases, very limited evidence for safety and efficacy, with most human evidence obtained in small clinical trials. Here we review work in animal models and humans with Alzheimer's disease exploring emerging neuromodulation modalities. Approaches reviewed include deep brain stimulation, transcranial magnetic stimulation, transcranial electrical stimulation, ultrasound stimulation, photobiomodulation, and visual or auditory stimulation. In doing so, we clarify the current evidence for these approaches in treating Alzheimer's disease and identify specific areas where additional work is needed to facilitate their clinical translation.

Deep brain stimulation for psychiatric disorders: role of imaging in identifying/confirming DBS targets, predicting, and optimizing outcome and unravelling mechanisms of action

Following the established application of deep brain stimulation (DBS) in the treatment of movement disorders, new non-neurological indications have emerged, such as for obsessive-compulsive disorders, major depressive disorder, dementia, Gilles de la Tourette Syndrome, anorexia nervosa, and addictions. As DBS is a network modulation surgical treatment, the development of DBS for both neurological and psychiatric disorders has been partly driven by advances in neuroimaging, which has helped explain the brain networks implicated. Advances in magnetic resonance imaging connectivity and electrophysiology have led to the development of the concept of modulating widely distributed, complex brain networks. Moreover, the increasing number of targets for treating psychiatric disorders have indicated that there may be a convergence of the effect of stimulating different targets for the same disorder, and the effect of stimulating the same target for different disorders. The aim of this paper is to review the imaging studies of DBS for psychiatric disorders. Imaging, and particularly connectivity analysis, offers exceptional opportunities to better understand and even predict the clinical outcomes of DBS, especially where there is a lack of objective biomarkers that are essential to properly guide DBS pre- and post-operatively. In future, imaging might also prove useful to individualize DBS treatment. Finally, one of the most important aspects of imaging in DBS is that it allows us to better understand the brain through observing the changes of the functional connectome under neuromodulation, which may in turn help explain the mechanisms of action of DBS that remain elusive.

Neuromodulatory treatments for psychiatric disease: A comprehensive survey of the clinical trial landscape

BACKGROUND

Numerous neuromodulatory therapies are currently under investigation or in clinical use for the treatment of psychiatric conditions.

OBJECTIVE/HYPOTHESIS

We sought to catalogue past and present human research studies on psychiatric neuromodulation and identify relevant trends in this field.

METHODS

ClinicalTrials.gov (https://www.clinicaltrials.gov/) and the International Clinical Trials Registry Platform (https://www.who.int/ictrp/en/) were queried in March 2020 for trials assessing the outcome of neuromodulation for psychiatric disorders. Relevant trials were categorized by variables such as neuromodulation modality, country, brain target, publication status, design, and funding source.

RESULTS

From 72,086 initial search results, 1252 unique trials were identified. The number of trials registered annually has consistently increased. Half of all trials were active and a quarter have translated to publications. The largest proportion of trials involved depression (45%), schizophrenia (18%), and substance use disorders (14%). Trials spanned 37 countries; China, the second largest contributor (13%) after the United States (28%), has increased its output substantially in recent years. Over 75% of trials involved non-convulsive non-invasive modalities (e.g., transcranial magnetic stimulation), while convulsive (e.g., electroconvulsive therapy) and invasive modalities (e.g., deep brain stimulation) were less represented. 72% of trials featured approved or cleared interventions. Characteristic inter-modality differences were observed with respect to enrollment size, trial design/phase, and funding. Dorsolateral prefrontal cortex accounted for over half of focal neuromodulation trial targets. The proportion of trials examining biological correlates of neuromodulation has increased.

CONCLUSION(S)

These results provide a comprehensive overview of the state of psychiatric neuromodulation research, revealing the growing scope and internationalism of this field.

Structuro-functional surrogates of response to subcallosal cingulate deep brain stimulation for depression

Subcallosal cingulate deep brain stimulation (SCC-DBS) produces long-term clinical improvement in approximately half of patients with severe treatment-resistant depression (TRD). We hypothesized that both structural and functional brain attributes may be important in determining responsiveness to this therapy. In a TRD SCC-DBS cohort, we retrospectively examined baseline and longitudinal differences in MRI-derived brain volume (n = 65) and 18F-fluorodeoxyglucose-PET glucose metabolism (n = 21) between responders and non-responders. Support-vector machines (SVMs) were subsequently trained to classify patients' response status based on extracted baseline imaging features. A machine learning model incorporating pre-operative frontopolar, precentral/frontal opercular, and orbitofrontal local volume values classified binary response status (12 months) with 83% accuracy (leave-one-out cross-validation (LOOCV): 80% accuracy) and explained 32% of the variance in continuous clinical improvement. It was also predictive in an out-of-sample SCC-DBS cohort (n = 21) with differing primary indications (bipolar disorder/anorexia nervosa) (76% accuracy). Adding pre-operative glucose metabolism information from rostral anterior cingulate cortex and temporal pole improved model performance, enabling it to predict response status in the TRD cohort with 86% accuracy (LOOCV: 81% accuracy) and explain 67% of clinical variance. Response-related patterns of metabolic and structural post-DBS change were also observed, especially in anterior cingulate cortex and neighbouring white matter. Areas where responders differed from non-responders - both at baseline and longitudinally - largely overlapped with depression-implicated white matter tracts, namely uncinate fasciculus, cingulum bundle, and forceps minor/rostrum of corpus callosum. The extent of patient-specific engagement of these same tracts (according to electrode location and stimulation parameters) also served as a predictor of TRD response status (72% accuracy; LOOCV: 70% accuracy) and augmented performance of the volume-based (88% accuracy; LOOCV: 82% accuracy) and combined volume/metabolism-based SVMs (100% accuracy; LOOCV: 94% accuracy). Taken together, these results indicate that responders and non-responders to SCC-DBS exhibit differences in brain volume and metabolism, both pre- and post-surgery. Baseline imaging features moreover predict response to treatment (particularly when combined with information about local tract engagement) and could inform future patient selection and other clinical decisions.

Directional Deep Brain Stimulation of the Posteromedial Hypothalamus for Refractory Intermittent Explosive Disorder: A Case Series Using a Novel Neurostimulation Device and Intraoperative Microdialysis

BACKGROUND

Intermittent explosive disorder (IED) is a psychiatric disorder characterized by recurrent outbursts of aggressive behavior. Deep brain stimulation (DBS) in the posteromedial nucleus of the hypothalamus (pHyp) is an alternative therapy for extreme cases and shows promising results. Intraoperative microdialysis can help elucidate the neurobiological mechanism of pHyp-DBS. We sought to evaluate efficacy and safety of pHyp-DBS using 8-contact directional leads in patients with refractory IED (rIED) and the accompanying changes in neurotransmitters.

METHODS

This was a prospective study in which patients with a diagnosis of rIED were treated with pHyp-DBS for symptom alleviation. Bilateral pHyp-DBS was performed with 8-contact directional electrodes. Follow-up was performed at 3, 6, and 12 months after surgery.

RESULTS

Four patients (3 men, mean age 27 ± 2.8 years) were included. All patients were diagnosed with rIED and severe intellectual disability. Two patients had congenital rubella, one had a co-diagnosis of infantile autism, and the fourth presented with drug-resistant epilepsy. There was a marked increase in the levels of gamma-aminobutyric acid and glycine during intraoperative stimulation. The average improvement in aggressive behavior in the last follow-up was 6 points (Δ: 50%, P = 0.003) while also documenting an important improvement of the Short Form Health Survey in all domains except bodily pain. No adverse events associated with pHyp-DBS were observed.

CONCLUSIONS

This is the first study to show the safety and beneficial effect of directional lead pHyp-DBS in patients with rIED and to demonstrate the corresponding mechanism of action through increases in gamma-aminobutyric acid and glycine concentration in the pHyp.

Optogenetically-inspired neuromodulation: Translating basic discoveries into therapeutic strategies

Optogenetic tools allow for the selective activation, inhibition or modulation of genetically-defined neural circuits with incredible temporal precision. Over the past decade, application of these tools in preclinical models of psychiatric disease has advanced our understanding the neural circuit basis of maladaptive behaviors in these disorders. Despite their power as an investigational tool, optogenetics cannot yet be applied in the clinical for the treatment of neurological and psychiatric disorders. To date, deep brain stimulation (DBS) is the only clinical treatment that can be used to achieve circuit-specific neuromodulation in the context of psychiatric. Despite its increasing clinical indications, the mechanisms underlying the therapeutic effects of DBS for psychiatric disorders are poorly understood, which makes optimization difficult. We discuss the variety of optogenetic tools available for preclinical research, and how these tools have been leveraged to reverse-engineer the mechanisms underlying DBS for movement and compulsive disorders. We review studies that have used optogenetics to induce plasticity within defined basal ganglia circuits, to alter neural circuit function and evaluate the corresponding effects on motor and compulsive behaviors. While not immediately applicable to patient populations, the translational power of optogenetics is in inspiring novel DBS protocols by providing a rationale for targeting defined neural circuits to ameliorate specific behavioral symptoms, and by establishing optimal stimulation paradigms that could selectively compensate for pathological synaptic plasticity within these defined neural circuits.

Deep brain stimulation in the management of paediatric neuropsychiatric conditions: Current evidence and future directions

INTRODUCTION

Neurosurgery has provided an alternative option for patients with refractory psychiatric indications. Lesion procedures were the initial techniques used, but deep brain stimulation (DBS) has the advantage of relative reversibility and adjustability. This review sets out to delineate the current evidence for DBS use in psychiatric conditions, with an emphasis on the paediatric population, highlighting pitfalls and opportunities.

METHODS

A systematic review of the literature was conducted on studies reporting the use of DBS in the management of psychiatric disorders. The PRISMA guidelines were employed to structure the review of the literature. Data was discussed focusing on the indications for DBS management of psychiatric conditions in the paediatric age group.

RESULTS

A total of seventy-three full-text papers reported the use of DBS surgery for the management of psychiatric conditions matching the inclusion criteria. The main indications were Tourette Syndrome (GTS) (15 studies), Obsessive Compulsive Disorder (OCD) (20), Treatment Resistant Depression (TRD) (27), Eating Disorders (ED) (7) and Aggressive Behaviour and self-harm (AB) (4). Out of these, only 11 studies included patients in the paediatric age group (≤18 years-old). Among the paediatric patients, the indications for surgery included GTS, AB and ED.

CONCLUSIONS

The application of deep brain stimulation for psychiatric indications has progressed at a steady pace in the adult population and at a much slower pace in the paediatric population. Future studies in children should be done in a trial setting with strict and robust criteria. A move towards personalising DBS therapy with new stimulation paradigms will provide new frontiers and possibilities in this growing field.

High-Frequency Deep Brain Stimulation of the Substantia Nigra Pars Reticulata Facilitates Extinction and Prevents Reinstatement of Methamphetamine-Induced Conditioned Place Preference

Persistent and stable drug memories lead to a high rate of relapse among addicts. A number of studies have found that intervention in addiction-related memories can effectively prevent relapse. Deep brain stimulation (DBS) exhibits distinct therapeutic effects and advantages in the treatment of neurological and psychiatric disorders. In addition, recent studies have also found that the substantia nigra pars reticulata (SNr) could serve as a promising target in the treatment of addiction. Therefore, the present study aimed to investigate the effect of DBS of the SNr on the reinstatement of drug-seeking behaviors. Electrodes were bilaterally implanted into the SNr of rats before training of methamphetamine-induced conditioned place preference (CPP). High-frequency (HF) or low-frequency (LF) DBS was then applied to the SNr during the drug-free extinction sessions. We found that HF DBS, during the extinction sessions, facilitated extinction of methamphetamine-induced CPP and prevented drug-primed reinstatement, while LF DBS impaired the extinction. Both HF and LF DBS did not affect locomotor activity or induce anxiety-like behaviors of rats. Finally, HF DBS had no effect on the formation of methamphetamine-induced CPP. In conclusion, our results suggest that HF DBS of the SNr could promote extinction and prevent reinstatement of methamphetamine-induced CPP, and the SNr may serve as a potential therapeutic target in the treatment of drug addiction.

The utility of deep brain stimulation surgery for treating eating disorders: A systematic review

Background:

Deep brain stimulation (DBS) has demonstrated preliminary success as a treatment for neuropsychological disorders including obsessive-compulsive disorder and substance use disorder. This systematic review aims to assess the use of DBS in treating eating disorders (EDs) to determine its utility and the extent of adverse effects.

Methods:

A PubMed search following PRISMA guidelines was executed to find studies encompassing DBS as a treatment of ED. Outcomes were extracted from the literature and summarized while a review of quality was also performed.

Results:

From a search yielding 299 publications, 11 studies published between 2010 and 2020 were found to fit the inclusion criteria. Out of 53 patients who began with an abnormal BMI before treatment, 22 patients (41.5%) achieved normal BMI on follow-up. Significant neuropsychological improvement was seen in most patients as measured by neuropsychiatric testing and questionnaires.

Conclusion:

DBS as a treatment for ED may result in significant objective and psychological benefits. Further studies should aim to increase the sample size, standardize follow-up protocol, and standardize the neuropsychiatric tests used to determine psychological and physiological benefits.

Role of the Anterior Cingulate Cortex in Translational Pain Research

As the most common symptomatic reason to seek medical consultation, pain is a complex experience that has been classified into different categories and stages. In pain processing, noxious stimuli may activate the anterior cingulate cortex (ACC). But the function of ACC in the different pain conditions is not well discussed. In this review, we elaborate the commonalities and differences from accumulated evidence by a variety of pain assays for physiological pain and pathological pain including inflammatory pain, neuropathic pain, and cancer pain in the ACC, and discuss the cellular receptors and signaling molecules from animal studies. We further summarize the ACC as a new central neuromodulation target for invasive and non-invasive stimulation techniques in clinical pain management. The comprehensive understanding of pain processing in the ACC may lead to bridging the gap in translational research between basic and clinical studies and to develop new therapies.

Alternatives to Pharmacological and Psychotherapeutic Treatments in Psychiatric Disorders

Nowadays, most of the patients affected by psychiatric disorders are successfully treated with psychotherapy and pharmacotherapy. Nevertheless, according to the disease, a variable percentage of patients results resistant to such modalities, and alternative methods can then be considered. The purpose of this review is to summarize the techniques and results of invasive modalities for several treatment-resistant psychiatric diseases. A literature search was performed to provide an up-to-date review of advantages, disadvantages, efficacy, and complications of Deep-Brain Stimulation, Magnetic Resonance-guided Focused-Ultrasound, radiofrequency, and radiotherapy lesioning for depression, obsessive-compulsive disorder, schizophrenia, addiction, anorexia nervosa, and Tourette’s syndrome. The literature search did not strictly follow the criteria for a systematic review: due to the large differences in methodologies and patients’ cohort, we tried to identify the highest quality of available evidence for each technique. We present the data as a comprehensive, narrative review about the role, indication, safety, and results of the contemporary instrumental techniques that opened new therapeutic fields for selected patients unresponsive to psychotherapy and pharmacotherapy.

Probabilistic Mapping of Deep Brain Stimulation: Insights from 15 Years of Therapy

Deep brain stimulation (DBS) depends on precise delivery of electrical current to target tissues. However, the specific brain structures responsible for best outcome are still debated. We applied probabilistic stimulation mapping to a retrospective, multidisorder DBS dataset assembled over 15 years at our institution (n_total = 482 patients; n_{Parkinson disease} = 303; n_dystonia = 64; n_tremor = 39; n_{treatment-resistant depression/anorexia nervosa} = 76) to identify the neuroanatomical substrates of optimal clinical response. Using high-resolution structural magnetic resonance imaging and activation volume modeling, probabilistic stimulation maps (PSMs) that delineated areas of above-mean and below-mean response for each patient cohort were generated and defined in terms of their relationships with surrounding anatomical structures. Our results show that overlap between PSMs and individual patients' activation volumes can serve as a guide to predict clinical outcomes, but that this is not the sole determinant of response. In the future, individualized models that incorporate advancements in mapping techniques with patient-specific clinical variables will likely contribute to the optimization of DBS target selection and improved outcomes for patients. ANN NEUROL 2021;89:426-443.

Deep brain stimulation (DBS) in resistant mental disorders

Introduction: Deep Brain Stimulation can directly alter brain activity in a controlled manner and the effect is reversible. The mechanism is that the electrode acts locally on neural activity, which is transferred to monosynchronous and multisynaptic network connections.

Methods: We present studies conducted on a group of patients that show an improvement in mental state after Deep Brain Stimulation.

Material: The diseases we included in our work are: Obsessive-Compulsive Disorder, Eating Disorder, Depression and Bipolar Affective Disorder.

Discussion: The use of deep brain stimulation can inhibit development of acute state of patients and improve both psychiatric features and the time of remission. The results indicate the greatest effectiveness of Deep Brain Stimulation in Obsessive-Compulsive Disorders.

Conclusions: Brain stimulation may be a promising therapeutic target in mental illness. In a properly selected location, it can contribute to a significant clinical improvement however further research in this direction is necessary.

Endovascular deep brain stimulation: Investigating the relationship between vascular structures and deep brain stimulation targets

BACKGROUND

Endovascular delivery of current using 'stentrodes' - electrode bearing stents - constitutes a potential alternative to conventional deep brain stimulation (DBS). The precise neuroanatomical relationships between DBS targets and the vascular system, however, are poorly characterized to date.

OBJECTIVE

To establish the relationships between cerebrovascular system and DBS targets and investigate the feasibility of endovascular stimulation as an alternative to DBS.

METHODS

Neuroanatomical targets as employed during deep brain stimulation (anterior limb of the internal capsule, dentatorubrothalamic tract, fornix, globus pallidus pars interna, medial forebrain bundle, nucleus accumbens, pedunculopontine nucleus, subcallosal cingulate cortex, subthalamic nucleus, and ventral intermediate nucleus) were superimposed onto probabilistic vascular atlases obtained from 42 healthy individuals. Euclidian distances between targets and associated vessels were measured. To determine the electrical currents necessary to encapsulate the predefined neurosurgical targets and identify potentially side-effect inducing substrates, a preliminary volume of tissue activated (VTA) analysis was performed.

RESULTS

Six out of ten DBS targets were deemed suitable for endovascular stimulation: medial forebrain bundle (vascular site: P1 segment of posterior cerebral artery), nucleus accumbens (vascular site: A1 segment of anterior cerebral artery), dentatorubrothalamic tract (vascular site: s2 segment of superior cerebellar artery), fornix (vascular site: internal cerebral vein), pedunculopontine nucleus (vascular site: lateral mesencephalic vein), and subcallosal cingulate cortex (vascular site: A2 segment of anterior cerebral artery). While VTAs effectively encapsulated mfb and NA at current thresholds of 3.5 V and 4.5 V respectively, incremental amplitude increases were required to effectively cover fornix, PPN and SCC target (mean voltage: 8.2 ± 4.8 V, range: 3.0-17.0 V). The side-effect profile associated with endovascular stimulation seems to be comparable to conventional lead implantation. Tailoring of targets towards vascular sites, however, may allow to reduce adverse effects, while maintaining the efficacy of neural entrainment within the target tissue.

CONCLUSIONS

While several challenges remain at present, endovascular stimulation of select DBS targets seems feasible offering novel and exciting opportunities in the neuromodulation armamentarium.

Changes in eating behavior after deep brain stimulation for anorexia nervosa. A case study

PURPOSE

The purpose of this study was to evaluate changes in the nutritional status, body image concerns, and eating behaviors occurring in a patient who underwent deep brain stimulation (DBS) of the bed nucleus of the stria terminalis for treatment-refractory anorexia nervosa (AN).

METHODS

Bilateral DBS of the bed nucleus of the stria terminalis was performed in a 37-year-old woman affected by refractory AN. Pre- and post-surgical evaluations were conducted via an array of validated testing instruments, which took into account the weight variations, body image concerns, eating behavior, quality of life, and nutritional status.

RESULTS

Overall, eating behavior-, body image concern-, and nutritional status-related testing instruments demonstrated improvements starting from the first post-operative month. Normal body weight was restored after 4 months of stimulation.

DISCUSSION

Only a few cases of DBS for AN have been conducted to determine the efficacy of surgery based upon weight variation and psychometric scales for anxiety and affective disorders. In contrast, we have designed a comprehensive approach taking into account the most important aspects of this disease. This approach should be considered in future studies dealing with the neurosurgical treatment of AN.

Treatment interventions for Severe and Enduring Eating Disorders: Systematic review

OBJECTIVE

Approximately 20% of people with Anorexia Nervosa (AN) and 10% with Bulimia Nervosa (BN) will eventually develop a long-standing illness. Although there is no set definition for Severe and Enduring eating Disorder (SE-ED), the common criteria relate to a long duration of the disorder and a number of unsuccessful treatment attempts. Research evidence for treatment of SE-ED remains limited, thus the objective of this systematic review was to describe different treatment interventions and their effects on SE-ED-related outcomes.

METHOD

A systematic search for quantitative treatment studies of adult participants with SE-ED was conducted in June 2019 (PROSPERO, CRD42018115802) with no restriction on eating disorder type. Altogether, 2,938 studies were included for title and abstract screening.

RESULTS

After systematic searches and article screening, 23 studies (3 randomized controlled trials, 3 open-label studies, 8 naturalistic follow-up studies, 8 case series and case studies, and 1 partially blinded pilot study) were included in the analysis and data extraction. Methodological quality of the included studies was generally low. Inpatient treatment programs (n = 5) were effective in short-term symptom reduction, but long-term results were inconsistent. Outpatient and day-hospital treatment programs (n = 5) seemed promising for symptom reduction. Drug interventions (n = 5) showed some benefits, especially as adjuvant therapies. Brain stimulation (n = 6) led to improvements in depressive symptoms. Other treatments (n = 2) produced mixed results.

DISCUSSION

This is the first systematic review to examine all of the different treatment interventions that have been studied in SE-ED. The results will inform future interventions in research and clinical practice.

Repetitive transcranial magnetic stimulation treatment in severe, enduring anorexia nervosa: An open longer-term follow-up

OBJECTIVE

This study assessed longer-term outcomes from a randomised controlled feasibility trial of 20 sessions of real versus sham high-frequency repetitive transcranial magnetic stimulation (rTMS) to the left dorsolateral prefrontal cortex in adults with severe, enduring anorexia nervosa (SE-AN).

METHODS

Thirty participants who completed the original study protocol were invited to take part in an open follow-up (18-months post-randomisation), assessing body mass index (BMI), eating disorder (ED) symptoms and other psychopathology.

RESULTS

Twenty-four participants (12 each originally allocated to real/sham) completed the 18-month follow-up. Ten of 12 participants who originally received sham treatment had real rTMS at some stage during the follow-up. A medium between-group effect size was seen for BMI change from baseline to 18-months, favouring those originally allocated to real rTMS. In this group at 18-months, five participants were weight recovered (BMI ≥18.5 kg/m² ), compared with one participant in the original sham group. Both groups showed further improvement in ED symptoms during the follow-up. Effects on mood were largely maintained at follow-up, with catch-up effects in the original sham group.

CONCLUSIONS

Findings suggest that rTMS treatment effects on mood are durable and that BMI and ED symptom improvements need time to emerge. Large-scale trials are needed.

A Randomized Trial of Deep Brain Stimulation to the Subcallosal Cingulate and Nucleus Accumbens in Patients with Treatment-Refractory, Chronic, and Severe Anorexia Nervosa: Initial Results at 6 Months of Follow Up

Background: The main objective of this study was to assess the safety and efficacy of deep brain stimulation (DBS) in patients with severe anorexia nervosa (AN). Methods: Eight participants received active DBS to the subcallosal cingulate (SCC) or nucleus accumbens (NAcc) depending on comorbidities (affective or anxiety disorders, respectively) and type of AN. The primary outcome measure was body mass index (BMI). Results: Overall, we found no significant difference (p = 0.84) between mean preoperative and postoperative (month 6) BMI. A BMI reference value (BMI-RV) was calculated. In patients that received preoperative inpatient care to raise the BMI, the BMI-RV was defined as the mean BMI value in the 12 months prior to surgery. In patients that did not require inpatient care, the BMI-RV was defined as the mean BMI in the 3-month period before surgery. This value was compared to the postoperative BMI (month 6), revealing a significant increase (p = 0.02). After 6 months of DBS, five participants showed an increase of ≥10% in the BMI-RV. Quality of life was improved (p = 0.03). Three cases presented cutaneous complications. Conclusion: DBS may be effective for some patients with severe AN. Cutaneous complications were observed. Longer term data are needed.

[Neural pathway between the nucleus accumbens and the rostral ventrolateral medulla in a rat model of anorexia nervosa]

OBJECTIVE

To investigate the potential neural pathway connecting the nucleus accumbens (NAc) and the rostral ventrolateral medulla (RVLM), and whether the pathway participates in the regulation of cardiovascular function in a model rat of anorexia nervosa (AN).

METHODS

Rat models of AN were established by allowing voluntary activity in a running wheel with restricted feeding, with the rats having free access to normal chow without exercise as the control group. FluoroGold (FG) retrograde tracing method and multi-channel simultaneous recording technique were used to explore the possible pathway between the NAc and the RVLM.

RESULTS

The rats in AN group exhibited significantly reduced systolic blood pressure (SBP), mean arterial pressure (MAP) and heart rate (HR) with significantly increased discharge frequency of RVLM neurons in comparison with the control rats. After the injection of FG into the RVLM, retrograde labeled neurons were observed in the NAc of the rats in both the normal control and AN groups. In both groups, SBP and HR were significantly decreased in response to 400 μA electrical stimulation of the NAc accompanied by an obvious increase in the discharge frequency of the RVLM neurons; the diastolic blood pressure (DBP) and MAP were significantly lower in AN model rats than in the normal rats in response to the stimulation.

CONCLUSIONS

We successfully established a rat model of AN via hyperactivity and restricted feeding and confirm the presence of a neural pathway connecting the NAc and the RVLM. This pathway might participate in the regulation of cardiovascular function in AN model rats.

Cognitive Interpersonal Model for Anorexia Nervosa Revisited: The Perpetuating Factors that Contribute to the Development of the Severe and Enduring Illness

The cognitive interpersonal model was outlined initially in 2006 in a paper describing the valued and visible aspects of anorexia nervosa (Schmidt and Treasure, 2006). In 2013, we summarised many of the cognitive and emotional traits underpinning the model (Treasure and Schmidt, 2013). In this paper, we describe in more detail the perpetuating aspects of the model, which include the inter- and intrapersonal related consequences of isolation, depression, and chronic stress that accumulate in the severe and enduring stage of the illness. Since we developed the model, we have been using it to frame research and development at the Maudsley. We have developed and tested interventions for both patients and close others, refining the model through iterative cycles of model/intervention development in line with the Medical Research Council (MRC) framework for complex interventions. For example, we have defined the consequences of living with the illness on close others (including medical professionals) and characterised the intense emotional reactions and behaviours that follow. For the individual with an eating disorder, these counter-reactions can allow the eating disorder to become entrenched. In addition, the consequent chronic stress from starvation and social pain set in motion processes such as depression, neuroprogression, and neuroadaptation. Thus, anorexia nervosa develops a life of its own that is resistant to treatment. In this paper, we describe the underpinnings of the model and how this can be targeted into treatment.

Deep brain stimulation of the nucleus accumbens for treatment-refractory anorexia nervosa: A long-term follow-up study

BACKGROUND

Given that anorexia nervosa (AN) is a life-threatening mental disorder and has poor clinical outcomes, novel effective treatments are warranted, especially for severe and persistent cases.

OBJECTIVE

To investigate the safety, feasibility, and clinical outcomes of using deep brain stimulation (DBS) of the nucleus accumbens (NAcc) in treatment-refractory AN patients.

METHODS

A total of 28 women with refractory AN underwent NAcc-DBS and completed this 2-year follow-up study. The clinical outcomes, including body mass index (BMI) and mood, anxiety, and obsessive symptoms, were assessed using a series of psychiatric scales at 6 and 24 months post operation.

RESULTS

While no fatalities were reported during this study, 1 patient showed device rejection. The most common short-term side effect observed was varying degrees of pain at the incision sites (n = 22), which usually disappeared 3-4 days following the operation. No severe surgical adverse events were observed. Compared to presurgical levels, significant increases in BMI and improvement in psychiatric scale scores were noted during the 6-month follow-up and were maintained at the 2-year review. Finally, a post-hoc analysis revealed that the NAcc-DBS was less effective for weight restoration in patients with the binge-eating/purge subtype of AN than in those with the restricting subtype (R-AN).

CONCLUSION

Our long-term follow-up study suggests that NAcc-DBS is safe and effective for improving the BMI and psychiatric symptoms of patients with refractory AN. Although NAcc-DBS appears to be more suitable for patients with R-AN, strict inclusion criteria must be applied considering surgery-related complications.

Deep brain stimulation: current challenges and future directions

The clinical use of deep brain stimulation (DBS) is among the most important advances in the clinical neurosciences in the past two decades. As a surgical tool, DBS can directly measure pathological brain activity and can deliver adjustable stimulation for therapeutic effect in neurological and psychiatric disorders correlated with dysfunctional circuitry. The development of DBS has opened new opportunities to access and interrogate malfunctioning brain circuits and to test the therapeutic potential of regulating the output of these circuits in a broad range of disorders. Despite the success and rapid adoption of DBS, crucial questions remain, including which brain areas should be targeted and in which patients. This Review considers how DBS has facilitated advances in our understanding of how circuit malfunction can lead to brain disorders and outlines the key unmet challenges and future directions in the DBS field. Determining the next steps in DBS science will help to define the future role of this technology in the development of novel therapeutics for the most challenging disorders affecting the human brain.

Characterizing Treatment-Resistant Anorexia Nervosa

Background: The issue of treatment resistance in eating disorder care is controversial. Prior research has identified multiple failed treatment attempts as a common criterion for severe and enduring anorexia nervosa, but little is known about patients who have multiple failed treatment attempts. This study was designed to compare the clinical and demographic characteristics of eating disorder patients with multiple, incomplete inpatient admissions to those with good outcomes. Understanding if these patient populations differ at initial admissions has implications for the prediction and characterization of inpatient eating disorder treatment resistance. Methods: This study analyzed existing data from a specialist inpatient eating disorder program at a large Canadian teaching hospital collected between 2000 and 2016. Treatment resistance was defined as two or more incomplete admissions and no complete admissions in the study period. Data were available on 37 patients who met this criteria, and 38 patients who had completed their first admission and remained well (defined as a BMI > 18.5 with no binging or purging behavior) 1 year after discharge. Variables of interest included age, weight, diagnoses, duration of illness, eating disorder psychopathology, eating disorder behavioral frequencies and depressive symptoms at the time of index inpatient admissions. Statistical analyses consisted of Mann-Whitney U tests, Chi-square tests, and a logistic regression. Results: In our main bivariate analyses, patients with multiple incomplete admissions were characterized by more severe eating disorder psychopathology and depressive symptoms at admission as well as an increased prevalence of the binge purge subtype of anorexia nervosa. In our exploratory multivariate analyses controlling for diagnostic subtype and depressive symptoms, severity of eating disorder psychopathology did not remain significant. No statistically significant difference in body mass index (BMI) or frequencies of eating disorder behaviors were found. A trend toward a longer duration of illness did not meet statistical significance. Conclusions: This study found that patients considered resistant to inpatient eating disorder treatment differ from those with good outcomes at initial admission. These results suggest that while treatment-resistant anorexia nervosa may be related to severe and enduring anorexia nervosa, it may also be a different concept that warrants additional research.