Nucleus accumbens stimulation in pathological obesity

Appetite- and Weight-Regulating Neuroendocrine Circuitry in Hypothalamic Obesity

Since hypothalamic obesity (HyOb) was first described over 120 years ago by Joseph Babinski and Alfred Fröhlich, advances in molecular genetic laboratory techniques have allowed us to elucidate various components of the intricate neurocircuitry governing appetite and weight regulation connecting the hypothalamus, pituitary gland, brainstem, adipose tissue, pancreas, and gastrointestinal tract. On a background of an increasing prevalence of population-level common obesity, the number of survivors of congenital (eg, septo-optic dysplasia, Prader-Willi syndrome) and acquired (eg, central nervous system tumors) hypothalamic disorders is increasing, thanks to earlier diagnosis and management as well as better oncological therapies. Although to date the discovery of several appetite-regulating peptides has led to the development of a range of targeted molecular therapies for monogenic obesity syndromes, outside of these disorders these discoveries have not translated into the development of efficacious treatments for other forms of HyOb. This review aims to summarize our current understanding of the neuroendocrine physiology of appetite and weight regulation, and explore our current understanding of the pathophysiology of HyOb.

Deep Brain Stimulation for the Management of Refractory Neurological Disorders: A Comprehensive Review

In recent decades, deep brain stimulation (DBS) has been extensively studied due to its reversibility and significantly fewer side effects. DBS is mainly a symptomatic therapy, but the stimulation of subcortical areas by DBS is believed to affect the cytoarchitecture of the brain, leading to adaptability and neurogenesis. The neurological disorders most commonly studied with DBS were Parkinson's disease, essential tremor, obsessive-compulsive disorder, and major depressive disorder. The most precise approach to evaluating the location of the leads still relies on the stimulus-induced side effects reported by the patients. Moreover, the adequate voltage and DBS current field could correlate with the patient's symptoms. Implantable pulse generators are the main parts of the DBS, and their main characteristics, such as rechargeable capability, magnetic resonance imaging (MRI) safety, and device size, should always be discussed with patients. The safety of MRI will depend on several parameters: the part of the body where the device is implanted, the part of the body scanned, and the MRI-tesla magnetic field. It is worth mentioning that drug-resistant individuals may have different pathophysiological explanations for their resistance to medications, which could affect the efficacy of DBS therapy. Therefore, this could explain the significant difference in the outcomes of studies with DBS in individuals with drug-resistant neurological conditions.

Continuous deep brain stimulation of the nucleus accumbens reduces food intake but does not affect body weight in mice fed a high-fat diet

Obesity is an enormous health problem, and many patients do not respond to any of the available therapies. Deep brain stimulation (DBS) is currently investigated as a potential treatment for morbid obesity. In this study, we tested the hypothesis that high-frequency DBS targeting the nucleus accumbens (NAc) shell region reduces food intake and weight gain in mice fed a high-fat diet. We implanted male C57BL/6J mice with bilateral electrodes and a head-mounted microstimulator enabling continuous stimulation for up to 5 weeks. In successfully operated animals (n = 9 per group, high-frequency vs. sham stimulation), we investigated immediate and long-term stimulation effects on metabolic and behavioral phenotypes. Here we show that stimulation acutely induced a transient reduction in energy expenditure and locomotor activity but did not significantly affect spontaneous food intake, social interaction, anxiety or exploratory behaviors. In contrast, continuous stimulation over 5 weeks led to a decrease in food intake and thigmotaxis (the tendency to stay near walls in an open lit arena). However, chronic stimulation did not substantially change weight gain in mice fed a high-fat diet. Our results do not support the use of continuous high-frequency NAc shell DBS as a treatment for obesity. However, DBS can alter obesity-related parameters with differing short and long-term effects. Therefore, future research should employ time and context-sensitive experimental designs to assess the potential of DBS for clinical translation in this area.

Novel Insights into the Physiology of Nutrient Sensing and Gut-Brain Communication in Surgical and Experimental Obesity Therapy

Despite standardized surgical technique and peri-operative care, metabolic outcomes of bariatric surgery are not uniform. Adaptive changes in brain function may play a crucial role in achieving optimal postbariatric weight loss. This review follows the anatomic-physiologic structure of the postbariatric nutrient-gut-brain communication chain through its key stations and provides a concise summary of recent findings in bariatric physiology, with a special focus on the composition of the intestinal milieu, intestinal nutrient sensing, vagal nerve-mediated gastrointestinal satiation signals, circulating hormones and nutrients, as well as descending neural signals from the forebrain. The results of interventional studies using brain or vagal nerve stimulation to induce weight loss are also summarized. Ultimately, suggestions are made for future diagnostic and therapeutic research for the treatment of obesity.

Accumbens connectivity during deep-brain stimulation differentiates loss of control from physiologic behavioral states

BACKGROUND

Loss of control (LOC) eating, the subjective sense that one cannot control what or how much one eats, characterizes binge-eating behaviors pervasive in obesity and related eating disorders. Closed-loop deep-brain stimulation (DBS) for binge eating should predict LOC and trigger an appropriately timed intervention.

OBJECTIVE/HYPOTHESIS

This study aimed to identify a sensitive and specific biomarker to detect LOC onset for DBS. We hypothesized that changes in phase-locking value (PLV) predict the onset of LOC-associated cravings and distinguish them from potential confounding states.

METHODS

Using DBS data recorded from the nucleus accumbens (NAc) of two patients with binge eating disorder (BED) and severe obesity, we compared PLV between inter- and intra-hemispheric NAc subregions for three behavioral conditions: craving (associated with LOC eating), hunger (not associated with LOC), and sleep.

RESULTS

In both patients, PLV in the high gamma frequency band was significantly higher for craving compared to sleep and significantly higher for hunger compared to craving. Maximum likelihood classifiers achieved accuracies above 88% when differentiating between the three conditions.

CONCLUSIONS

High-frequency inter- and intra-hemispheric PLV in the NAc is a promising biomarker for closed-loop DBS that differentiates LOC-associated cravings from physiologic states such as hunger and sleep. Future trials should assess PLV as a LOC biomarker across a larger cohort and a wider patient population transdiagnostically.

Contemporary Biological Insights and Clinical Management of Craniopharyngioma

Craniopharyngiomas (CPs) are clinically aggressive tumors because of their invasive behavior and recalcitrant tendency to recur after therapy. There are 2 types based on their distinct histology and molecular features: the papillary craniopharyngioma (PCP), which is associated with BRAF-V600E mutations and the adamantinomatous craniopharyngioma (ACP), characterized by mutations in CTNNB1 (encoding β-catenin). Patients with craniopharyngioma show symptoms linked to the location of the tumor close to the optic pathways, hypothalamus, and pituitary gland, such as increased intracranial pressure, endocrine deficiencies, and visual defects. Treatment is not specific and mostly noncurative, and frequently includes surgery, which may achieve gross total or partial resection, followed by radiotherapy. In cystic tumors, frequent drainage is often required and intracystic instillation of drugs has been used to help manage cyst refilling. More recently targeted therapies have been used, particularly in PCP, but also now in ACP and clinical trials are underway or in development. Although patient survival is high, the consequences of the tumor and its treatment can lead to severe comorbidities resulting in poor quality of life, in particular for those patients who bear tumors with hypothalamic involvement. Accordingly, in these patients at risk for the development of a hypothalamic syndrome, hypothalamus-sparing treatment strategies such as limited resection followed by irradiation are recommended. In this review, we provide an update on various aspects of CP, with emphasis on recent advances in the understanding of tumor pathogenesis, clinical consequences, management, and therapies.

Invasive Computational Psychiatry

Computational psychiatry, a relatively new yet prolific field that aims to understand psychiatric disorders with formal theories about the brain, has seen tremendous growth in the past decade. Despite initial excitement, actual progress made by computational psychiatry seems stagnant. Meanwhile, understanding of the human brain has benefited tremendously from recent progress in intracranial neuroscience. Specifically, invasive techniques such as stereotactic electroencephalography, electrocorticography, and deep brain stimulation have provided a unique opportunity to precisely measure and causally modulate neurophysiological activity in the living human brain. In this review, we summarize progress and drawbacks in both computational psychiatry and invasive electrophysiology and propose that their combination presents a highly promising new direction-invasive computational psychiatry. The value of this approach is at least twofold. First, it advances our mechanistic understanding of the neural computations of mental states by providing a spatiotemporally precise depiction of neural activity that is traditionally unattainable using noninvasive techniques with human subjects. Second, it offers a direct and immediate way to modulate brain states through stimulation of algorithmically defined neural regions and circuits (i.e., algorithmic targeting), thus providing both causal and therapeutic insights. We then present depression as a use case where the combination of computational and invasive approaches has already shown initial success. We conclude by outlining future directions as a road map for this exciting new field as well as presenting cautions about issues such as ethical concerns and generalizability of findings.

Could deep brain stimulation be a possible solution for acquired hypothalamic obesity?

Objective

Hypothalamic dysfunction may result in morbid obesity as a consequence of decreased energy expenditure, decreased feelings of satiety, and increased fat storage. In patients with hypothalamic dysfunction, neurobehavioral dysfunction is also often present. Currently, no effective treatment has been found for hypothalamic obesity (HO). We hypothesize that deep brain stimulation (DBS) may be an effective treatment for patients with hypothalamic dysfunction, aiming to treat HO as well as the neurobehavioral dysfunction.

Methods

A systematic search was conducted in the PubMed, EMBASE and Cochrane Library databases for studies published until May 2022 reporting on DBS for the treatment of HO.

Results

Three studies met the predetermined inclusion criteria, with in total six patients treated with DBS for HO, of which five patients with Prader-Willi syndrome (PWS) and one patient with HO after treatment for craniopharyngioma (CP). Targets of DBS included the lateral hypothalamic area (LHA) and the nucleus accumbens (NAcc). In patients with PWS, LHA-DBS was associated with a mean increase of Body Mass Index (BMI) (+5.8%), with no change in hormonal levels, results of blood workup, sleep, or neuropsychological evaluation. In the patient with CP, NAcc-DBS was associated with a decrease in BMI (-8.7%) and a subjective increase in mental health, energy and willingness to act, and no feeling of increased appetite. No objective measurements on neurobehavioral function were reported. No severe adverse events were reported in these cases. Mild to moderate adverse events included hypomanic symptoms and infection. All patients with a described follow-up period (n = 5) were able to sustain the treatment for at least 6 months with few interruptions.

Conclusion

There is limited research reporting on DBS for HO. The effectiveness differed across studies and the evidence is limited. Although there may be potential for DBS treatment in the severe-refractory condition of HO in patients with CP, more research is needed for target selection and evaluation of effectiveness.

Deep Brain Stimulation for Morbid Obesity: An Underutilized Neuromodulatory Treatment for Severely Obese Patients?

Background Morbid obesity (MO) has been steadily increasing in the last few years. Pharmacotherapy and bariatric surgeries remain the main treatment modalities for MO, although in the long-term they may lose their effectiveness. Other treatment approaches are urgently needed and deep brain stimulation (DBS) is a promising therapy. Disturbed energy homeostasis caused by intake of highly palatable and caloric foods may induce hedonic eating. The brain nuclei responsible for energy homeostasis and hedonia are the hypothalamic nuclei and nucleus accumbens. These brain structures constitute the stereotactic targets approached with DBS to treat MO.

Material and Methods We have performed a literature search of all available clinical applications of DBS for MO in humans. We were able to identify three case series reports and additional six case reports involving 16 patients. The selected stereotactic targets included lateral hypothalamus in eight patients, ventromedial hypothalamus in two patients, and nucleus accumbens in six patients.

Results In general, the safety profile of DBS in refractory MO patients was good. Clinical improvement regarding the mean body mass index could be observed in obese patients.

Conclusions MO is a demanding condition. Since in some cases standardized treatment is ineffective, new therapies should be implemented. DBS is a promising therapy that might be used in patients suffering from MO, however, more studies incorporating more individuals and with a longer follow-up are needed to obtain more reliable results concerning its effectiveness and safety profile.

Hypothalamic syndrome

Hypothalamic syndrome (HS) is a rare disorder caused by disease-related and/or treatment-related injury to the hypothalamus, most commonly associated with rare, non-cancerous parasellar masses, such as craniopharyngiomas, germ cell tumours, gliomas, cysts of Rathke's pouch and Langerhans cell histiocytosis, as well as with genetic neurodevelopmental syndromes, such as Prader-Willi syndrome and septo-optic dysplasia. HS is characterized by intractable weight gain associated with severe morbid obesity, multiple endocrine abnormalities and memory impairment, attention deficit and reduced impulse control as well as increased risk of cardiovascular and metabolic disorders. Currently, there is no cure for this condition but treatments for general obesity are often used in patients with HS, including surgery, medication and counselling. However, these are mostly ineffective and no medications that are specifically approved for the treatment of HS are available. Specific challenges in HS are because the syndrome represents an adverse effect of different diseases, and that diagnostic criteria, aetiology, pathogenesis and management of HS are not completely defined.

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.

Cognitive and quality-of-life related factors of body mass index (BMI) improvement after deep brain stimulation in the subcallosal cingulate and nucleus accumbens in treatment-refractory chronic anorexia nervosa

BACKGROUND

Up to 20% of the cases of anorexia nervosa (AN) are chronic and treatment-resistant. Recently, the efficacy of deep brain stimulation (DBS) for severe cases of AN has been explored, with studies showing an improvement in body mass index and other psychiatric outcomes. While the effects of DBS on cognitive domains have been studied in patients with other neurological and psychiatric conditions so far, no evidence has been gathered in AN.

METHODS

Eight patients with severe, chronic, treatment-resistant AN received DBS either to the nucleus accumbens (NAcc) or subcallosal cingulate (SCC; four subjects on each target). A comprehensive battery of neuropsychological and clinical outcomes was used before and 6-month after surgery.

FINDINGS

Although Body Mass Index (BMI) did not normalise, statistically significant improvements in BMI, quality of life, and performance on cognitive flexibility were observed after 6 months of DBS. Changes in BMI were related to a decrease in depressive symptoms and an improvement in memory functioning.

INTERPRETATION

These findings, although preliminary, support the use of DBS in AN, pointing to its safety, even for cognitive functioning; improvements of cognitive flexibility are reported. DBS seems to exert changes on cognition and mood that accompany BMI increments. Further studies are needed better to determine the impact of DBS on cognitive functions.

Can responsive deep brain stimulation be a cost-effective treatment for severe obesity?

OBJECTIVE

A first-in-human responsive deep brain stimulation (rDBS) trial (NCT03868670) for obesity is under way, which is based on promising preclinical evidence. Given the upfront costs of rDBS, it is prudent to examine the success threshold for cost-effectiveness compared with laparoscopic Roux-en-Y gastric bypass (LRYGB).

METHODS

Efficacy and safety data on LRYGB and safety data on rDBS were collected for established indications through a literature search. The success threshold was defined as minimum BMI reduction. Treatment costs were calculated via Medicare national reimbursement data.

RESULTS

LRYGB had a mean BMI reduction of 13.75 kg/m² . Based on adverse events, LRYGB was a less-preferred health state (overall adverse event utility of 0.96 [0.02]) than rDBS (0.98 [0.01]), but LRYGB ($14,366 [$6,410]) had a significantly lower treatment cost than rDBS ($29,951 [$4,490]; p < 0.0001). Therefore, for rDBS to be cost-effective compared with LRYGB, the multiple models yielded a success threshold range of 13.7 to 15.2 kg/m² .

CONCLUSIONS

This study established a preliminary efficacy success threshold for rDBS to be cost-effective for severe obesity, and results from randomized controlled trials are needed. This analysis allows for interpretation of the economic impact of advancing rDBS for obesity in light of ongoing trial results and suggests an attainable threshold is needed for cost-effectiveness.

Treatment of Acquired Hypothalamic Obesity: Now and the Future

The hypothalamus is the centre of neuroendocrine regulation of energy homeostasis and appetite. Maldevelopment of, or damage to, the key hypothalamic nuclei disrupts the coordinated balance between energy intake and expenditure leading, to rapid and excessive weight gain. Hypothalamic obesity is compounded by a disruption of the hypothalamic-pituitary axis, sleep disruption, visual compromise, and neurological and vascular sequalae. Amongst suprasellar tumors, craniopharyngioma is the most common cause of acquired hypothalamic obesity, either directly or following surgical or radiotherapeutic intervention. At present, therapy is limited to strategies to manage obesity but with a modest and variable impact. Current approaches include optimizing pituitary hormone replacement, calorie restriction, increased energy expenditure through physical activity, behavioral interventions, pharmacotherapy and bariatric surgery. Current pharmacotherapeutic approaches include stimulants that increase energy consumption, anti-diabetic agents, hypothalamic-pituitary substitution therapy, octreotide, and methionine aminopeptidase 2 (MetAP2) inhibitors. Some pharmacological studies of hypothalamic obesity report weight loss or stabilization but reported intervention periods are short, and others report no effect. The impact of bariatric surgery on weight loss in hypothalamic obesity again is variable. Novel or combined approaches to manage hypothalamic obesity are thus required to achieve credible and sustained weight loss. Identifying etiological factors contributing hypothalamic obesity may lead to multi-faceted interventions targeting hyperphagia, insulin resistance, decreased energy expenditure, sleep disturbance, hypopituitarism and psychosocial morbidity. Placebo-controlled trials using current single, or combination therapies are required to determine the impact of therapeutic agents. A well-defined approach to defining the location of hypothalamic damage may support the use of future targeted therapies. Intranasal oxytocin is currently being investigated as an anorexogenic agent. Novel agents including those targeting pro-opimelanocortin-C and AgRP/NPY expressing neurons and the MC4 receptor may result in better outcomes. This article discusses the current challenges in the management of hypothalamic obesity in children and young people and future therapeutic approaches to increasing weight loss and quality of life in these patients.

The role of the nucleus accumbens and ventral pallidum in feeding and obesity

Obesity is a growing global epidemic that stems from the increasing availability of highly-palatable foods and the consequent enhanced calorie consumption. Extensive research has shown that brain regions that are central to reward seeking modulate feeding and evidence linking obesity to pathology in such regions have recently started to accumulate. In this review we focus on the contribution of two major interconnected structures central to reward processing, the nucleus accumbens and the ventral pallidum, to obesity. We first review the known literature linking these structures to feeding behavior, then discuss recent advances connecting pathology in the nucleus accumbens and ventral pallidum to obesity, and finally examine the similarities and differences between drug addiction and obesity in the context of these two structures. The understanding of how pathology in brain regions involved in reward seeking and consumption may drive obesity and how mechanistically similar obesity and addiction are, is only now starting to be revealed. We hope that future research will advance knowledge in the field and open new avenues to studying and treating obesity.

A systematic review on neuromodulation therapies for reducing body weight in patients with obesity

The global prevalence of obesity increases yearly along with a rising demand for efficacious, safe, and accessible treatments. Neuromodulation interventions (i.e., deep brain stimulation [DBS], transcranial magnetic stimulation [TMS], transcranial direct current stimulation [tDCS], percutaneous neurostimulation [PENS], vagus nerve stimulation [VNS], and gastric electrical stimulation [GES]) have been proposed as novel therapies. This systematic review sought to examine the safety and efficacy of neuromodulation therapies in reducing body weight in patients with obesity. Using PRISMA guidelines, we performed a systematic review for studies on neuromodulation for the treatment of obesity, resulting in 60 trials included (7 DBS, 5 TMS, 7 tDCS, 17 PENS and VNS, and 24 GES; a total of 3,042 participants). While promising results have been reported in open label studies, double-blinded randomized clinical trials often did not reach their primary endpoints, with no technique inducing a striking reduction in body weight. Bearing in mind the complexity and multifactorial nature of obesity, it is possible that a single treatment may not be enough for patients to lose or maintain the weight lost at long term.

Effectiveness of Deep Brain Stimulation in Reducing Body Mass Index and Weight: A Systematic Review

BACKGROUND

Obesity has become a major public health concern worldwide, with current behavioral, pharmacological, and surgical treatments offering varying rates of success and adverse effects. Neurosurgical approaches to treatment of refractory obesity include deep brain stimulation (DBS) on either specific hypothalamic or reward circuitry nuclei, which might contribute to weight reduction through different mechanisms. We aimed to determine the safety and clinical effect of DBS in medical refractory obesity.

SUMMARY

Adhering to PRISMA guidelines, we performed a systematic review to identify all original studies - observational and experimental - in which DBS was performed to treat refractory obesity. From database inception to April 2021, we conducted our search in PubMed, Scopus, and LILACS databases using the following MeSH terms: "Obesity" OR "Prader-Willi Syndrome" AND "Deep Brain Stimulation." The main outcomes were safety and weight loss measured with the body mass index (BMI). The Grading of Recommendations Assessment, Development, and Evaluation methods were applied to evaluate the quality of evidence. This study protocol was registered with PROSPERO ID: CRD42019132929. Seven studies involving 12 patients met the inclusion criteria; the DBS target was the nucleus accumbens in four (57.1%), the lateral hypothalamic area in two (29.6%), and the ventral hypothalamus in one (14.3%). Further, 33% of participants had obesity secondary to Prader-Willi syndrome (PWS) and 66.6% had primary obesity. The global BMI average at baseline was 46.7 (SD: 9.6, range: 32.2-59.1), and after DBS, 42.8 (SD: 8.8, range: 25-53.9), with a mean difference of 3.9; however, the delta in PWS patients was -2.3 and 10 in those with primary obesity. The incidence of moderate side effects was 33% and included manic symptoms (N = 2), electrode fracture (N = 1), and seizure (N = 1); mild complications (41.6%) included skin infection (N = 2), difficulties falling asleep (N = 1), nausea (N = 1), and anxiety (N = 1). Key Messages: Despite available small case series and case reports reporting a benefit in the treatment of refractory obesity with DBS, this study emphasizes the need for prospective studies with longer follow-ups in order to further address the efficacy and indications.

A Systematic Review of Obesity and Binge Eating Associated Impairment of the Cognitive Inhibition System

Altered functioning of the inhibition system and the resulting higher impulsivity are known to play a major role in overeating. Considering the great impact of disinhibited eating behavior on obesity onset and maintenance, this systematic review of the literature aims at identifying to what extent the brain inhibitory networks are impaired in individuals with obesity. It also aims at examining whether the presence of binge eating disorder leads to similar although steeper neural deterioration. We identified 12 studies that specifically assessed impulsivity during neuroimaging. We found a significant alteration of neural circuits primarily involving the frontal and limbic regions. Functional activity results show BMI-dependent hypoactivity of frontal regions during cognitive inhibition and either increased or decreased patterns of activity in several other brain regions, according to their respective role in inhibition processes. The presence of binge eating disorder results in further aggravation of those neural alterations. Connectivity results mainly report strengthened connectivity patterns across frontal, parietal, and limbic networks. Neuroimaging studies suggest significant impairment of various neural circuits involved in inhibition processes in individuals with obesity. The elaboration of accurate therapeutic neurocognitive interventions, however, requires further investigations, for a deeper identification and understanding of obesity-related alterations of the inhibition brain system.

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.

Exploratory study of the long-term footprint of deep brain stimulation on brain metabolism and neuroplasticity in an animal model of obesity

Deep brain stimulation (DBS) is a powerful neurostimulation therapy proposed for the treatment of several neuropsychiatric disorders. However, DBS mechanism of action remains unclear, being its effects on brain dynamics of particular interest. Specifically, DBS reversibility is a major point of debate. Preclinical studies in obesity showed that the stimulation of the lateral hypothalamus (LH) and nucleus accumbens (NAcc), brain centers involved in satiety and reward circuits, are able to modulate the activity of brain structures impaired in this pathology. Nevertheless, the long-term persistence of this modulation after DBS withdrawal was unexplored. Here we examine the in vivo presence of such changes 1 month after LH- and NAcc-DBS, along with differences in synaptic plasticity, following an exploratory approach. Thus, both stimulated and non-stimulated animals with electrodes in the NAcc showed a common pattern of brain metabolism modulation, presumably derived from the electrodes' presence. In contrast, animals stimulated in the LH showed a relative metabolic invariance, and a reduction of neuroplasticity molecules, evidencing long-lasting neural changes. Our findings suggest that the reversibility or persistence of DBS modulation in the long-term depends on the selected DBS target. Therefore, the DBS footprint would be influenced by the stability achieved in the neural network involved during the stimulation.

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.

Brain-Responsive Neurostimulation for Loss of Control Eating: Early Feasibility Study

BACKGROUND

Loss of control (LOC) is a pervasive feature of binge eating, which contributes significantly to the growing epidemic of obesity; approximately 80 million US adults are obese. Brain-responsive neurostimulation guided by the delta band was previously found to block binge-eating behavior in mice. Following novel preclinical work and a human case study demonstrating an association between the delta band and reward anticipation, the US Food and Drug Administration approved an Investigational Device Exemption for a first-in-human study.

OBJECTIVE

To assess feasibility, safety, and nonfutility of brain-responsive neurostimulation for LOC eating in treatment-refractory obesity.

METHODS

This is a single-site, early feasibility study with a randomized, single-blinded, staggered-onset design. Six subjects will undergo bilateral brain-responsive neurostimulation of the nucleus accumbens for LOC eating using the RNS® System (NeuroPace Inc). Eligible participants must have treatment-refractory obesity with body mass index ≥ 45 kg/m2. Electrophysiological signals of LOC will be characterized using real-time recording capabilities coupled with synchronized video monitoring. Effects on other eating disorder pathology, mood, neuropsychological profile, metabolic syndrome, and nutrition will also be assessed.

EXPECTED OUTCOMES

Safety/feasibility of brain-responsive neurostimulation of the nucleus accumbens will be examined. The primary success criterion is a decrease of ≥1 LOC eating episode/week based on a 28-d average in ≥50% of subjects after 6 mo of responsive neurostimulation.

DISCUSSION

This study is the first to use brain-responsive neurostimulation for obesity; this approach represents a paradigm shift for intractable mental health disorders.

Obesity and Related Type 2 Diabetes: A Failure of the Autonomic Nervous System Controlling Gastrointestinal Function?

The pandemic spread of obesity and type 2 diabetes is a serious health problem that cannot be contained with common therapies. At present, the most effective therapeutic tool is metabolic surgery, which substantially modifies the gastrointestinal anatomical structure. This review reflects the state of the art research in obesity and type 2 diabetes, describing the probable reason for their spread, how the various brain sectors are involved (with particular emphasis on the role of the vagal system controlling different digestive functions), and the possible mechanisms for the effectiveness of bariatric surgery. According to the writer’s interpretation, the identification of drugs that can modulate the activity of some receptor subunits of the vagal neurons and energy-controlling structures of the central nervous system (CNS), and/or specific physical treatment of cortical areas, could reproduce, non-surgically, the positive effects of metabolic surgery.

Nucleus Accumbens Functional Connectivity with the Frontoparietal Network Predicts Subsequent Change in Body Mass Index for American Children

Background: Nucleus accumbens (NAc) is a brain structure with a well-established role in the brain reward processing system. Altered function of the NAc is shown to have a role in the development of food addiction and obesity. However, less is known about sex differences in the role of NAc function as a predictor of children’s change in body mass index (BMI) over time. Aim: We used the Adolescent Brain Cognitive Development data (version 2.01) to investigate sex differences in the predictive role of the NAc functional connectivity with the frontoparietal network on children’s BMI change over a one-year follow-up period. Methods: This 1-year longitudinal study successfully followed 3784 9–10-year-old children. Regression models were used to analyze the data. The predictor variable was NAc functional connectivity with the frontoparietal network measured using resting-state functional magnetic resonance imaging (fMRI). The primary outcome was BMI at the end of the 1-year follow up. Covariates included race, ethnicity, age, socioeconomic factors, and baseline BMI. Sex was the effect modifier. Results: NAc functional connectivity with the frontoparietal network was predictive of BMI changes over time. This association remained significant above and beyond all covariates. The above association, however, was only significant in female, not male children. Conclusion: The epidemiological observation that NAc functional connectivity is associated with BMI changes in children is an extension of well-controlled laboratory studies that have established the role of the NAc in the brain reward processing. More research is needed on sex differences in the brain regions that contribute to childhood obesity.

Management of Hypothalamic Obesity

Energy homeostasis, appetite, and satiety are modulated by a complex neuroendocrine system regulated by the hypothalamus. Dysregulation of this system resulting in hypothalamic obesity (HO) is caused by brain tumors, neurosurgery, and/or cranial irradiation. Craniopharyngioma (CP) is a paradigmatic disease with regard to the development of HO. Initial hypothalamic involvement of CP and/or treatment-related damage to hypothalamic-pituitary axes result in HO. Attempts to control HO with lifestyle interventions have not been satisfactory. No generally accepted pharmacologic or bariatric therapy for HO in CP has been effective in randomized controlled trials. Accordingly, prevention of HO is recommended.

Deep Brain Stimulation of Nucleus Accumbens with Anterior Capsulotomy for Drug Addiction: A Case Report

BACKGROUND

Drug addiction is one of the most prevalent and costly health problems worldwide. Over the past decade, deep brain stimulation (DBS) has increasingly been used for the treatment of drug addiction. Simultaneous DBS of nucleus accumbens (NAc) and the anterior limb of the internal capsule (ALIC) has successfully been used for preventing heroin relapse. However, the excessive energy consumption speeds up battery depletion, which puts a burden on patients. By comparison, anterior capsulotomy is usually more convenient for patients and its clinical efficacy is similar to that of ALIC DBS. Accordingly, NAc DBS combined with anterior capsulotomy may also be an effective, yet more convenient, intervention for drug addiction and relapse prevention.

CASE DESCRIPTION

The patient was a 28-year-old man with a polysubstance use disorder (bucinnazine, morphine, and hypnotics) for 13 years. After bilateral NAc DBS combined with bilateral anterior capsulotomy, his craving for the three drugs decreased markedly, and he remained abstinent throughout the follow-up period of approximately 1-year. Moreover, psychiatric and neuropsychological assessments showed significant improvements in depression, anxiety, sleep, quality of life, and most aspects of cognitive functioning. His overall health status was also improved.

CONCLUSIONS

NAc DBS combined with anterior capsulotomy is a promising surgical treatment for drug addiction.

Experiences with Glucagon-Like Peptide-1 Receptor Agonist in Children with Acquired Hypothalamic Obesity

OBJECTIVE

Hypothalamic obesity (HO) in children after treatment for a tumor in the suprasellar region has severe implications. Previous studies have shown various effects of glucagon-like peptide-1 (GLP-1) receptor agonist in acquired HO, but in adults only. We present our experience of GLP-1 receptor agonist (exenatide) treatment during a 1-year period on body mass index (BMI) in children with acquired HO.

PATIENTS AND METHODS

Children with severe weight gain after treatment for suprasellar tumor were given 2 mg exenatide weekly for a 12-month period. All had undergone previous dietary intervention. BMI standard deviation score (SDS), weight change, and adverse effects were assessed.

RESULTS

Five children with a mean age of 15.4 years (range 13-18) and a mean follow-up time of 8.4 years (mean age of 7.0 years at the time of brain tumor diagnosis) were treated with GLP-1 receptor agonist. After 1 year, BMI SDS or absolute weight had not changed significantly compared to the period without treatment (BMI SDS change +0.005, 95% CI -0.07 to 0.08, p = 0.89, and absolute weight change +1.5 kg, 95% CI -0.08 to 3.1, p = 0.061). Only 1 patient experienced weight loss after 1 year (-5.4 kg, BMI SDS -0.33). All patients experienced mild side effects, such as injection pain or nausea, and 2 patients stopped treatment upon their own request after 8 and 11 months, respectively.

CONCLUSIONS

In this small cohort, we found little effect of GLP-1 receptor agonist in the treatment for acquired HO. Future research should focus on the prevention of HO or, if prevention is not possible, on alternative, individualized interventions.

Cognitive Task Performance During Titration Predicts Deep Brain Stimulation Treatment Efficacy: Evidence From a Case Study

Device titration is a major challenge when using deep brain stimulation (DBS) to treat behavioral disorders. Unlike in movement disorders, there is no reliable real-time clinical feedback for changes in complex behaviors resulting from DBS. Here, a female patient receiving DBS of the nucleus accumbens for the treatment of morbid obesity underwent cognitive testing via the flanker task alongside traditional methods of device titration. One set of stimulation parameters administered during titration resulted in acute cognitive improvement (p = 0.033) and increased frontal engagement as measured by electroencephalography (left anterior: p = 0.007, right anterior: p = 0.005) relative to DBS-OFF. The same parameters resulted in the most weight-loss during long-term continuous stimulation (47.8 lbs lost in 129 days) compared to the results of other stimulation settings. Diffusion tensor imaging analyses showed increased connectivity to dorsal attention networks and decreased connectivity to the default mode network for optimal parameters (p < 0.01). Our results provide evidence that targeted cognitive testing is a potentially useful tool for capturing acute effects of DBS stimulation during titration and predicting long-term treatment outcomes.

CLINICAL TRIAL REGISTRATION

www.ClinicalTrials.gov, identifier: NCT01512134.

Deep brain stimulation for appetite disorders: a review

The mechanisms of appetite disorders, such as refractory obesity and anorexia nervosa, have been vigorously studied over the last century, and these studies have shown that the central nervous system has significant involvement with, and responsibility for, the pathology associated with these diseases. Because deep brain stimulation has been shown to be a safe, efficacious, and adjustable treatment modality for a variety of other neurological disorders, it has also been studied as a possible treatment for appetite disorders. In studies of refractory obesity in animal models, the ventromedial hypothalamus, the lateral hypothalamus, and the nucleus accumbens have all demonstrated elements of success as deep brain stimulation targets. Multiple targets for deep brain stimulation have been proposed for anorexia nervosa, with research predominantly focusing on the subcallosal cingulate, the nucleus accumbens, and the stria terminalis and medial forebrain bundle. Human deep brain stimulation studies that focus specifically on refractory obesity and anorexia nervosa have been performed but with limited numbers of patients. In these studies, the target for refractory obesity has been the lateral hypothalamus, ventromedial hypothalamus, and nucleus accumbens, and the target for anorexia nervosa has been the subcallosal cingulate. These studies have shown promising findings, but further research is needed to elucidate the long-term efficacy of deep brain stimulation for the treatment of appetite disorders.

Weight Change after Striatal/Capsule Deep Brain Stimulation Relates to Connectivity to the Bed Nucleus of the Stria Terminalis and Hypothalamus

Weight changes are insufficiently understood adverse events of deep brain stimulation. In this context, exploring neural networks of weight control may inform novel treatment strategies for weight-related disorders. In this study, we investigated weight changes after deep brain stimulation of the ventral striatum/ventral capsule and to what extent changes are associated with connectivity to feeding-related networks. We retrospectively analyzed 25 patients undergoing deep brain stimulation for obsessive-compulsive disorder or substance dependency. Weight changes were assessed preoperatively and six to twelve months after surgery and then matched with individual stimulation sites and stimulation-dependent functional connectivity to a priori defined regions of interest that are involved in food intake. We observed a significant weight gain after six to twelve months of continuous stimulation. Weight increases were associated with medial/apical localization of stimulation sites and with connectivity to hypothalamic areas and the bed nucleus. Thus, deep brain stimulation of the ventral striatum/ventral capsule influences weight depending on localization and connectivity of stimulation sites. Bearing in mind the significance of weight-related disorders, we advocate further prospective studies investigating the neuroanatomical and neuropsychological underpinnings of food intake and their neuromodulatory therapeutic potential.

Current and future directions of deep brain stimulation for neurological and psychiatric disorders

Deep brain stimulation (DBS) has evolved considerably over the past 4 decades. Although it has primarily been used to treat movement disorders such as Parkinson's disease, essential tremor, and dystonia, recently it has been approved to treat obsessive-compulsive disorder and epilepsy. Novel potential indications in both neurological and psychiatric disorders are undergoing active study. There have been significant advances in DBS technology, including preoperative and intraoperative imaging, surgical approaches and techniques, and device improvements. In addition to providing significant clinical benefits and improving quality of life, DBS has also increased the understanding of human electrophysiology and network interactions. Despite the value of DBS, future developments should be aimed at developing less invasive techniques and attaining not just symptom improvement but curative disease modification.

Deep Brain Stimulation for Obesity: A Review and Future Directions

The global prevalence of obesity has been steadily increasing. Although pharmacotherapy and bariatric surgeries can be useful adjuvants in the treatment of morbid obesity, they may lose long-term effectiveness. Obesity result largely from unbalanced energy homeostasis. Palatable and densely caloric foods may affect the brain overlapped circuits involved with homeostatic hypothalamus and hedonic feeding. Deep brain stimulation (DBS) consists of delivering electrical impulses to specific brain targets to modulate a disturbed neuronal network. In selected patients, DBS has been shown to be safe and effective for movement disorders. We review all the cases reports and series of patients treated with DBS for obesity using a PubMed search and will address the following obesity-related issues: (i) the hypothalamic regulation of homeostatic feeding; (ii) the reward mesolimbic circuit and hedonic feeding; (iii) basic concepts of DBS as well as the rationale for obesity treatment; (iv) perspectives and challenges in obesity DBS. The small number of cases provides preliminary evidence for the safety and the tolerability of a potential DBS approach. The ventromedial (n = 2) and lateral (n = 8) hypothalamic nuclei targets have shown mixed and disappointing outcomes. Although nucleus accumbens (n = 7) targets were more encouraging for the outcomes of body weight reduction and behavioral control for eating, there was one suicide reported after 27 months of follow-up. The authors did not attribute the suicide to DBS therapy. The identification of optimal brain targets, appropriate programming strategies and the development of novel technologies will be important as next steps to move DBS closer to a clinical application. The identification of electrical control signals may provide an opportunity for closed-loop adaptive DBS systems to address obesity. Metabolic and hormonal sensors such as glycemic levels, leptin, and ghrelin levels are candidate control signals for DBS. Focused excitation or alternatively inhibition of regions of the hypothalamus may provide better outcomes compared to non-selective DBS. Utilization of the NA delta oscillation or other physiological markers from one or multiple regions in obesity-related brain network is a promising approach. Experienced multidisciplinary team will be critical to improve the risk-benefit ratio for this approach.

Pathophysiology and Individualized Treatment of Hypothalamic Obesity Following Craniopharyngioma and Other Suprasellar Tumors: A Systematic Review

The development of hypothalamic obesity (HO) following craniopharyngioma (CP) and other suprasellar tumors leads to reduced patient quality of life. No treatment algorithms are currently available for management of HO. Depending on which hypothalamic nuclei are destroyed, the pathophysiologic mechanisms and clinical symptoms that contribute to HO differ among patients. Herein, we review the contribution of the hypothalamus to the pathophysiologic mechanisms and symptoms underlying CP-associated HO. Additionally, we performed a systematic search of MEDLINE and Embase to identify all intervention studies for weight management in patients with CP or other suprasellar tumors published until September 2017. The search yielded 1866 publications, of which 40 were included. Of these 40 studies, we identified four modalities for intervention (i.e., lifestyle, dietary, pharmacotherapeutic, or surgical) within six clinical domains (i.e., psychosocial disorders, hyperphagia, sleep disturbances, decreased energy expenditure, hyperinsulinemia, and hypopituitarism). We used the findings from our systematic review, in addition to current knowledge on the pathophysiology of HO, to develop an evidence-based treatment algorithm for patients with HO caused by CP or other suprasellar tumors. Although the individual effects of the HO interventions were modest, beneficial individual effects may be achieved when the pathophysiologic background and correct clinical domain are considered. These two aspects can be combined in an individualized treatment algorithm with a stepwise approach for each clinical domain. Recently elucidated targets for HO intervention were also explored to improve future management of HO for patients with CP and other suprasellar tumors.

Invasive and Non-invasive Stimulation of the Obese Human Brain

Accumulating evidence suggests that non-invasive and invasive brain stimulation may reduce food craving and calorie consumption rendering these techniques potential treatment options for obesity. Non-invasive transcranial direct current stimulation (tDCS) or repetitive transcranial magnet stimulation (rTMS) are used to modulate activity in superficially located executive control regions, such as the dorsolateral prefrontal cortex (DLPFC). Modulation of the DLPFC’s activity may alter executive functioning and food reward processing in interconnected dopamine-rich regions such as the striatum or orbitofrontal cortex. Modulation of reward processing can also be achieved by invasive deep brain stimulation (DBS) targeting the nucleus accumbens. Another target for DBS is the lateral hypothalamic area potentially leading to improved energy expenditure. To date, available evidence is, however, restricted to few exceptional cases of morbid obesity. The vagal nerve plays a crucial role in signaling the homeostatic demand to the brain. Invasive or non-invasive vagal nerve stimulation (VNS) is thus assumed to reduce appetite, rendering VNS another possible treatment option for obesity. Based on currently available evidence, the U.S. Food and Drug Administration recently approved VNS for the treatment of obesity. This review summarizes scientific evidence regarding these techniques’ efficacy in modulating food craving and calorie intake. It is time for large controlled clinical trials that are necessary to translate currently available research discoveries into patient care.

Assessment of Safety and Outcome of Lateral Hypothalamic Deep Brain Stimulation for Obesity in a Small Series of Patients With Prader-Willi Syndrome

IMPORTANCE

Deep brain stimulation (DBS) has been investigated for treatment of morbid obesity with variable results. Patients with Prader-Willi syndrome (PWS) present with obesity that is often difficult to treat.

OBJECTIVE

To test the safety and study the outcome of DBS in patients with PWS.

DESIGN, SETTING, AND PARTICIPANTS

This case series was conducted in the Hospital das Clínicas, University of São Paulo, Brazil. Four patients with genetically confirmed PWS presenting with severe obesity were included.

EXPOSURE

Deep brain stimulation electrodes were bilaterally implanted in the lateral hypothalamic area. After DBS implantation, the treatment included the following phases: titration (1-2 months), stimulation off (2 months), low-frequency DBS (40 Hz; 1 month), washout (15 days), high-frequency DBS (130 Hz; 1 month), and long-term follow-up (6 months).

MAIN OUTCOMES AND MEASURES

Primary outcome measures were adverse events recorded during stimulation and long-term DBS treatment. Secondary outcomes consisted of changes in anthropometric measures (weight, body mass index [calculated as weight in kilograms divided by height in meters squared], and abdominal and neck circumference), bioimpedanciometry, and calorimetry after 6 months of treatment compared with baseline. The following evaluations and measurements were conducted before and after DBS: clinical, neurological, psychiatric, neuropsychological, anthropometry, calorimetry, blood workup, hormonal levels, and sleep studies. Adverse effects were monitored during all follow-up visits.

RESULTS

Four patients with PWS were included (2 male and 2 female; ages 18-28 years). Baseline mean (SD) body mass index was 39.6 (11.1). Two patients had previous bariatric surgery, and all presented with psychiatric comorbidity, which was well controlled with the use of medications. At 6 months after long-term DBS, patients had a mean 9.6% increase in weight, 5.8% increase in body mass index, 8.4% increase in abdominal circumference, 4.2% increase in neck circumference, 5.3% increase in the percentage of body fat, and 0% change in calorimetry compared with baseline. Also unchanged were hormonal levels and results of blood workup, sleep studies, and neuropsychological evaluations. Two patients developed stimulation-induced manic symptoms. Discontinuation of DBS controlled this symptom in 1 patient. The other required adjustments in medication dosage. Two infections were documented, 1 associated with skin picking.

CONCLUSIONS AND RELEVANCE

Safety of lateral hypothalamic area stimulation was in the range of that demonstrated in patients with similar psychiatric conditions receiving DBS. In the small cohort of patients with PWS treated in our study, DBS was largely ineffective.

Stimulating the nucleus accumbens in obesity: A positron emission tomography study after deep brain stimulation in a rodent model

PURPOSE

The nucleus accumbens (NAcc) has been suggested as a possible target for deep brain stimulation (DBS) in the treatment of obesity. Our hypothesis was that NAcc-DBS would modulate brain regions related to reward and food intake regulation, consequently reducing the food intake and, finally, the weight gain. Therefore, we examined changes in brain glucose metabolism, weight gain and food intake after NAcc-DBS in a rat model of obesity.

PROCEDURES

Electrodes were bilaterally implanted in 2 groups of obese Zucker rats targeting the NAcc. One group received stimulation one hour daily during 15 days, while the other remained as control. Weight and daily consumption of food and water were everyday registered the days of stimulation, and twice per week during the following month. Positron emission tomography (PET) studies with 2-deoxy-2-[18F]fluoro-D-glucose (FDG) were performed 1 day after the end of DBS. PET data was assessed by statistical parametric mapping (SPM12) software and region of interest (ROI) analyses.

RESULTS

NAcc-DBS lead to increased metabolism in the cingulate-retrosplenial-parietal association cortices, and decreased metabolism in the NAcc, thalamic and pretectal nuclei. Furthermore, ROIs analyses confirmed these results by showing a significant striatal and thalamic hypometabolism, and a cortical hypermetabolic region. However, NAcc-DBS did not induce a decrease in either weight gain or food intake.

CONCLUSIONS

NAcc-DBS led to changes in the metabolism of regions associated with cognitive and reward systems, whose impairment has been described in obesity.

SAGES review of endoscopic and minimally invasive bariatric interventions: a review of endoscopic and non-surgical bariatric interventions

BACKGROUND

With obesity continuing as a global epidemic and therapeutic technologies advancing, several novel endoscopic and minimally invasive interventions will likely become available as treatment options. With improved technologies and different treatment strategies, as well as different patient populations being targeted, there will be greater application in the treatment armamentarium of specialists dedicated to treating obesity. We sought to review the existing technology and provide a review.

METHODS

Literature review was carried out for endoscopic and minimally invasive devices. Some of these products are not FDA approved, so limited data are available in their review.

RESULTS

A summary of the device and data currently available on weight loss and safety profile is provided. Several products are in clinical trials or will be soon. Some of the technology has limited data and companies will be submitting their results for FDA evaluation.

CONCLUSIONS

The obesity epidemic and associated weight-related diseases represent a tremendous burden to health care practitioners. As such, a multi-modal and progressive approach, with data and outcomes examined, is likely the best and most comprehensive method to care for these patients. SAGES endorses the benefits of minimally invasive and endoscopic approaches in the treatment of obesity and its related co-morbidities.

An Open-Label Clinical Trial of Hypothalamic Deep Brain Stimulation for Human Morbid Obesity: BLESS Study Protocol

BACKGROUND

Human morbid obesity is increasing worldwide in an alarming way. The hypothalamus is known to mediate its mechanisms. Deep brain stimulation (DBS) of the ventromedial hypothalamus (VMH) may be an alternative to treat patients refractory to standard medical and surgical therapies.

OBJECTIVE

To assess the safety, identify possible side effects, and to optimize stimulation parameters of continuous VMH-DBS. Additionally, this study aims to determine if continuous VMH-DBS will lead to weight loss by causing changes in body composition, basal metabolism, or food intake control.

METHODS

The BLESS study is a feasibility study, single-center open-label trial. Six patients (body mass index &gt; 40) will undergo low-frequency VMH-DBS. Data concerning timing, duration, frequency, severity, causal relationships, and associated electrical stimulation patterns regarding side effects or weight changes will be recorded.

EXPECTED OUTCOMES

We expect to demonstrate the safety, identify possible side effects, and to optimize electrophysiological parameters related to VMH-DBS. No clinical or behavioral adverse changes are expected. Weight loss ≥ 3% of the basal weight after 3 mo of electrical stimulation will be considered adequate. Changes in body composition and increase in basal metabolism are expected. The amount of food intake is likely to remain unchanged.

DISCUSSION

The design of this study protocol is to define the safety of the procedure, the surgical parameters important for target localization, and additionally the safety of long-term stimulation of the VMH in morbidly obese patients. Novel neurosurgical approaches to treat metabolic and autonomic diseases can be developed based on the data made available by this investigation.

Deep brain stimulation as a therapeutic option for obesity: A critical review

Despite a better understanding of obesity pathophysiology, treating this disease remains a challenge. New therapeutic options are needed. Targeting the brain is a promising way, considering both the brain abnormalities in obesity and the effects of bariatric surgery on the gut-brain axis. Deep brain stimulation could be an alternative treatment for obesity since this safe and reversible neurosurgical procedure modulates neural circuits for therapeutic purposes. We aimed to provide a critical review of published clinical and preclinical studies in this field. Owing to the physiology of eating and brain alterations in people with obesity, two brain areas, namely the hypothalamus and the nucleus accumbens are putative targets. Preclinical studies with animal models of obesity showed that deep brain stimulation of hypothalamus or nucleus accumbens induces weight loss. The mechanisms of action remain to be fully elucidated. Preclinical data suggest that stimulation of nucleus accumbens reduces food intake, while stimulation of hypothalamus could increase resting energy expenditure. Clinical experience with deep brain stimulation for obesity remains limited to six patients with mixed results, but some clinical trials are ongoing. Thus, drawing clear conclusions about the effectiveness of this treatment is not yet possible, even if the results of preclinical studies are encouraging. Future clinical studies should examine its efficacy and safety, while preclinical studies could help understand its mechanisms of action. We hope that our review will provide ways to design further studies.

Neuromodulation for the treatment of eating disorders and obesity

Eating disorders and obesity adversely affect individuals both medically and psychologically, leading to reduced life expectancy and poor quality of life. While there exist a number of treatments for anorexia, morbid obesity and bulimia, many patients do not respond favorably to current behavioral, medical or bariatric surgical management. Neuromodulation has been postulated as a potential treatment for eating disorders and obesity. In particular, deep brain stimulation and transcranial non-invasive brain stimulation have been studied for these indications across a variety of brain targets. Here, we review the neurobiology behind eating and eating disorders as well as the current status of preclinical and clinical neuromodulation trials for eating disorders and obesity.

Massive weight loss following deep brain stimulation of the nucleus accumbens in a depressed woman

Obese individuals share behavioral characteristics with drug/alcohol addicts as well as obsessive compulsive disease. Deep brain stimulation (DBS) has been used successfully in these disorders, thus warranting an evaluation in obesity. A woman with treatment-resistant depression as well as severe obesity was selected for DBS of the nucleus accumbens (NAcc) bilaterally with depression being the primary and obesity being the secondary target of treatment. Compared to earlier bariatric surgery, the patient showed accelerated weight loss after DBS. Also, depression was significantly reduced. The current case suggests that DBS of the NAcc warrants further evaluation in patients unresponsive to other treatments.

Deep Brain Stimulation-Possible Treatment Strategy for Pathologically Altered Body Weight?

The treatment of obesity and eating disorders such as binge-eating disorder or anorexia nervosa is challenging. Besides lifestyle changes and pharmacological options, bariatric surgery represents a well-established and effective-albeit invasive-treatment of obesity, whereas for binge-eating disorder and anorexia nervosa mostly psychotherapy options exist. Deep brain stimulation (DBS), a method that influences the neuronal network, is by now known for its safe and effective applicability in patients with Parkinson’s disease. However, the use does not seem to be restricted to these patients. Recent preclinical and first clinical evidence points towards the use of DBS in patients with obesity and eating disorders as well. Depending on the targeted area in the brain, DBS can either inhibit food intake and body weight or stimulate energy intake and subsequently body weight. The current review focuses on preclinical and clinical evidence of DBS to modulate food intake and body weight and highlight the different brain areas targeted, stimulation protocols applied and downstream signaling modulated. Lastly, this review will also critically discuss potential safety issues and gaps in knowledge to promote further studies.

Neuromodulation and neurofeedback treatments in eating disorders and obesity

PURPOSE OF REVIEW

Psychological interventions are the treatment of choice for most eating disorders; however, significant proportions of patients do not recover with these. Advances in understanding of the neurobiology of eating disorders have led to the development of targeted treatments, such as deep brain stimulation (DBS), noninvasive brain stimulation (NIBS), and neurofeedback. We review the emerging clinical evidence for the use of these interventions in eating disorders and obesity, together with their theoretical rationale. Finally, we reflect on future developments.

RECENT FINDINGS

During the last 20 months, seven case studies/series and seven randomized controlled trials (RCTs) of NIBS or neurofeedback in different eating disorders, obesity, or food craving have appeared. These have largely had promising results. One NIBS trial, using a multisession protocol, was negative. A case series of subcallosal DBS in anorexia nervosa has also shown promise. A search of trial registries identified a further 21 neuromodulation/feedback studies in progress, indicating that neuromodulation/feedback is an area of growing interest.

SUMMARY

At present, neuromodulation and neurofeedback are largely experimental interventions; however, growing understanding of the mechanisms involved, together with the rising number of studies in this area, means that the clinical utility of these interventions is likely to become clearer soon.

Lateral hypothalamic activity indicates hunger and satiety states in humans

Lateral hypothalamic area (LHA) local field potentials (LFPs) were recorded in a Prader–Willi patient undergoing deep brain stimulation (DBS) for obesity. During hunger, exposure to food‐related cues induced an increase in beta/low‐gamma activity. In contrast, recordings during satiety were marked by prominent alpha rhythms. Based on these findings, we have delivered alpha‐frequency DBS prior to and during food intake. Despite reporting an early sensation of fullness, the patient continued to crave food. This suggests that the pattern of activity in LHA may indicate hunger/satiety states in humans but attest to the complexity of conducting neuromodulation studies in obesity.

Innovative solutions in bariatric surgery

Nowadays all over the world the rising plague of obesity can be observed. The obesity was recognized as "an epidemic of XXI century" in 1997 by World Health Organization. The change of eating habits, active lifestyle or pharmacological curation are often insufficient to fight against obesity. Nowadays, there are not any guidelines about gold standard for curing obese patients is bariatric surgery. At the moment, two types of bariatric procedures: laparoscopic Roux-en-Y gastric bypass and laparoscopic sleeve gastrectomy, are most commonly used. There are also some other new approaches, which are still being investigated. The mechanism of losing weight in bariatric surgery is based on restriction, malabsorption and neurohormonal effect. Not only is the surgery technique very important to succeed, but also the postoperative care in the outpatient clinic. This article reviews the new possibilities in obesity treatment.

DBS for Obesity

Obesity is a chronic, progressive and prevalent disorder. Morbid obesity, in particular, is associated with numerous comorbidities and early mortality. In patients with morbid obesity, pharmacological and behavioral approaches often have limited results. Bariatric surgery is quite effective but is associated with operative failures and a non-negligible incidence of side effects. In the last decades, deep brain stimulation (DBS) has been investigated as a neurosurgical modality to treat various neuropsychiatric disorders. In this article we review the rationale for selecting different brain targets, surgical results and future perspectives for the use of DBS in medically refractory obesity.