Intermittent bilateral deep brain stimulation of the nucleus accumbens shell reduces intravenous methamphetamine intake and seeking in Wistar rats

Deep brain stimulation for psychostimulant use disorders

Safe and effective therapeutics for psychostimulant use disorders remain elusive. Deep brain stimulation (DBS), which is FDA-approved for other indications, is a promising candidate for treating severe substance use disorders. We examine the clinical and preclinical evidence for DBS of the nucleus accumbens as a possible therapeutic option for cocaine and methamphetamine use disorders. Limitations of the literature to date, including the lack of females included in studies evaluating the efficacy of DBS, and new strategies to optimize brain stimulation approaches are also discussed.

A wide range of Deep Brain Stimulation of the nucleus accumbens shell time independently reduces the extinction period and prevents the reinstatement of methamphetamine-seeking behavior in rats

Methamphetamine (METH) addiction is a significant public health issue, and standard medical therapies are often not curative. Deep Brain Stimulation (DBS) has recently shown the potential to cure addiction by modulating neural activity in specific brain circuits. Recent studies have revealed that the nucleus accumbens shell (NAcSh) could serve as a promising target in treating addiction. Therefore, the present study aimed to investigate the therapeutic effects of NAcSh high- or low-frequency stimulation (HFS or LFS) in the different time points of application on the extinction and reinstatement of the METH-conditioned place preference (CPP). LFS or HFS (10 or 130 Hz, 150-200 μA, 100 μs) was delivered to the NAcSh for 30 min non-simultaneous (in a distinct non-drug environment) or simultaneous (in a drug-paired context) of the drug-free extinction sessions. The obtained results showed that both non-simultaneous and simultaneous treatments by HFS and LFS notably reduced the extinction period of METH-induced CPP. Furthermore, the data indicated that both non-synchronous and synchronous HFS prevented METH-primed reinstatement, while only the LFS synchronized group could block the reinstatement of METH-seeking behavior. The results also demonstrated that HFS was more effective than LFS in attenuating METH-primed reinstatement, and applying HFS synchronous was significantly more effective than HFS non-synchronous in reducing the relapse of drug-seeking. In conclusion, the current study's results suggest that DBS of the NAcSh in a wide range of frequencies (LFS and HFS) could affect addiction-related behaviors. However, it should be considered that the frequency and timing of DBS administration are among the critical determining factors.

High frequency deep brain stimulation can mitigate the acute effects of cocaine administration on tonic dopamine levels in the rat nucleus accumbens

Cocaine's addictive properties stem from its capacity to increase tonic extracellular dopamine levels in the nucleus accumbens (NAc). The ventral tegmental area (VTA) is a principal source of NAc dopamine. To investigate how high frequency stimulation (HFS) of the rodent VTA or nucleus accumbens core (NAcc) modulates the acute effects of cocaine administration on NAcc tonic dopamine levels multiple-cyclic square wave voltammetry (M-CSWV) was used. VTA HFS alone decreased NAcc tonic dopamine levels by 42%. NAcc HFS alone resulted in an initial decrease in tonic dopamine levels followed by a return to baseline. VTA or NAcc HFS following cocaine administration prevented the cocaine-induced increase in NAcc tonic dopamine. The present results suggest a possible underlying mechanism of NAc deep brain stimulation (DBS) in the treatment of substance use disorders (SUDs) and the possibility of treating SUD by abolishing dopamine release elicited by cocaine and other drugs of abuse by DBS in VTA, although further studies with chronic addiction models are required to confirm that. Furthermore, we demonstrated the use of M-CSWV can reliably measure tonic dopamine levels in vivo with both drug administration and DBS with minimal artifacts.

Neurobiological mechanisms and related clinical treatment of addiction: a review

Drug addiction or substance use disorder (SUD), has been conceptualized as a three-stage (i.e. binge/intoxication, withdrawal/negative affect, and preoccupation/anticipation/craving) recurring cycle that involves complex changes in neuroplasticity, reward, motivation, desire, stress, memory, and cognitive control, and other related brain regions and brain circuits. Neuroimaging approaches, including magnetic resonance imaging, have been key to mapping neurobiological changes correlated to complex brain regions of SUD. In this review, we highlight the neurobiological mechanisms of these three stages of addiction. The abnormal activity of the ventral tegmental, nucleus accumbens, and caudate nucleus in the binge/intoxication stage involve the reward circuit of the midbrain limbic system. The changes in the orbitofrontal cortex, dorsolateral prefrontal cortex, amygdala, and hypothalamus emotional system in the withdrawal/negative affect stage involve increases in negative emotional states, dysphoric-like effects, and stress-like responses. The dysregulation of the insula and prefrontal lobes is associated with craving in the anticipation stage. Then, we review the present treatments of SUD based on these neuroimaging findings. Finally, we conclude that SUD is a chronically relapsing disorder with complex neurobiological mechanisms and multimodal stages, of which the craving stage with high relapse rate may be the key element in treatment efficacy of SUD. Precise interventions targeting different stages of SUD and characteristics of individuals might serve as a potential therapeutic strategy for SUD.

Is Deep Brain Stimulation an Effective Treatment for Psychostimulant Dependency? A Preclinical and Clinical Systematic Review

Addiction to psychostimulants significantly affects public health. Standard medical therapy is often not curative. Deep brain stimulation (DBS) is a promising treatment that has attracted much attention for addiction treatment in recent years. The present review aimed to systematically identify the positive and adverse effects of DBS in human and animal models to evaluate the feasibility of DBS as a treatment for psychostimulant abuse. The current study also examined the possible mechanisms underlying the therapeutic effects of DBS. In February 2022, a comprehensive search of four databases, including Web of Science, PubMed, Cochrane, and Scopus, was carried out to identify all reports that DBS was a treatment for psychostimulant addiction. The selected studies were extracted, summarized, and evaluated using the appropriate methodological quality assessment tools. The results indicated that DBS could reduce relapse and the desire for the drug in human and animal subjects without any severe side effects. The underlying mechanisms of DBS are complex and likely vary from region to region in terms of stimulation parameters and patterns. DBS seems a promising therapeutic option. However, clinical experiences are currently limited to several uncontrolled case reports. Further studies with controlled, double-blind designs are needed. In addition, more research on animals and humans is required to investigate the precise role of DBS and its mechanisms to achieve optimal stimulation parameters and develop new, less invasive methods.

Deep Brain Stimulation for Addictive Disorders-Where Are We Now?

In the face of a global epidemic of drug addiction, neglecting to develop new effective therapies will perpetuate the staggering human and economic costs of substance use. This review aims to summarize and evaluate the preclinical and clinical studies of deep brain stimulation (DBS) as a novel therapy for refractory addiction, in hopes to engage and inform future research in this promising novel treatment avenue. An electronic database search (MEDLINE, EMBASE, Cochrane library) was performed using keywords and predefined inclusion criteria between 1974 and 6/18/2021 (registered on Open Science Registry). Selected articles were reviewed in full text and key details were summarized and analyzed to understand DBS' therapeutic potential and possible mechanisms of action. The search yielded 25 animal and 22 human studies. Animal studies showed that DBS of targets such as nucleus accumbens (NAc), insula, and subthalamic nucleus reduces drug use and seeking. All human studies were case series/reports (level 4/5 evidence), mostly targeting the NAc with generally positive outcomes. From the limited evidence in the literature, DBS, particularly of the NAc, appears to be a reasonable last resort option for refractory addictive disorders. We propose that future research in objective electrophysiological (e.g., local field potentials) and neurochemical (e.g., extracellular dopamine levels) biomarkers would assist monitoring the progress of treatment and developing a closed-loop DBS system. Preclinical literature also highlighted the prefrontal cortex as a promising DBS target, which should be explored in human research.

Deep brain stimulation for opioid use disorder: A systematic review of preclinical and clinical evidence

Opioid use disorder (OUD) is a chronic and complex disease characterized by repeated relapses and remissions. Deep brain stimulation (DBS) has been discussed again and again as a potentially helpful neuromodulatory procedure in this context. In this review, for the first time, we intended to systematically identify the positive and negative effects of DBS in human and animal models of opioid dependence to assess the viability of DBS as a treatment of OUD. Eligible studies were incorporated by a comprehensive literature search and evaluated through proper methodological quality assessment tools. Findings showed that the nucleus accumbens was the most stimulated brain target in human and animal studies, and DBS was applied chiefly in the form of high-frequency stimulation (HFS). DBS administration effectively reduced opioid craving and consumption in human and animal subjects dependent on opioids. DBS represents a valuable alternative strategy for treating intractable opioid addiction. Based on our systematic literature analysis, research efforts in this field should be continued.

Drug addiction: from bench to bedside

Drug addiction is responsible for millions of deaths per year around the world. Still, its management as a chronic disease is shadowed by misconceptions from the general public. Indeed, drug consumers are often labelled as "weak", "immoral" or "depraved". Consequently, drug addiction is often perceived as an individual problem and not societal. In technical terms, drug addiction is defined as a chronic, relapsing disease resulting from sustained effects of drugs on the brain. Through a better characterisation of the cerebral circuits involved, and the long-term modifications of the brain induced by addictive drugs administrations, first, we might be able to change the way the general public see the patient who is suffering from drug addiction, and second, we might be able to find new treatments to normalise the altered brain homeostasis. In this review, we synthetise the contribution of fundamental research to the understanding drug addiction and its contribution to potential novel therapeutics. Mostly based on drug-induced modifications of synaptic plasticity and epigenetic mechanisms (and their behavioural correlates) and after demonstration of their reversibility, we tried to highlight promising therapeutics. We also underline the specific temporal dynamics and psychosocial aspects of this complex psychiatric disease adding parameters to be considered in clinical trials and paving the way to test new therapeutic venues.

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.

Biomarkers and neuromodulation techniques in substance use disorders

Addictive disorders are a severe health concern. Conventional therapies have just moderate success and the probability of relapse after treatment remains high. Brain stimulation techniques, such as transcranial Direct Current Stimulation (tDCS) and Deep Brain Stimulation (DBS), have been shown to be effective in reducing subjectively rated substance craving. However, there are few objective and measurable parameters that reflect neural mechanisms of addictive disorders and relapse. Key electrophysiological features that characterize substance related changes in neural processing are Event-Related Potentials (ERP). These high temporal resolution measurements of brain activity are able to identify neurocognitive correlates of addictive behaviours. Moreover, ERP have shown utility as biomarkers to predict treatment outcome and relapse probability. A future direction for the treatment of addiction might include neural interfaces able to detect addiction-related neurophysiological parameters and deploy neuromodulation adapted to the identified pathological features in a closed-loop fashion. Such systems may go beyond electrical recording and stimulation to employ sensing and neuromodulation in the pharmacological domain as well as advanced signal analysis and machine learning algorithms. In this review, we describe the state-of-the-art in the treatment of addictive disorders with electrical brain stimulation and its effect on addiction-related neurophysiological markers. We discuss advanced signal processing approaches and multi-modal neural interfaces as building blocks in future bioelectronics systems for treatment of addictive disorders.

Deep brain stimulation for the treatment of drug addiction

Drug addiction represents a significant public health concern that has high rates of relapse despite optimal medical therapy and rehabilitation support. New therapies are needed, and deep brain stimulation (DBS) may be an effective treatment. The past 15 years have seen numerous animal DBS studies for addiction to various drugs of abuse, with most reporting decreases in drug-seeking behavior with stimulation. The most common target for stimulation has been the nucleus accumbens, a key structure in the mesolimbic reward pathway. In addiction, the mesolimbic reward pathway undergoes a series of neuroplastic changes. Chief among them is a relative hypofunctioning of the prefrontal cortex, which is thought to lead to the diminished impulse control that is characteristic of drug addiction. The prefrontal cortex, as well as other targets involved in drug addiction such as the lateral habenula, hypothalamus, insula, and subthalamic nucleus have also been stimulated in animals, with encouraging results. Although animal studies have largely shown promising results, current DBS studies for drug addiction primarily use stimulation during active drug use. More data are needed on the effect of DBS during withdrawal in preventing future relapse. The published human experience for DBS for drug addiction is currently limited to several promising case series or case reports that are not controlled. Further animal and human work is needed to determine what role DBS can play in the treatment of drug addiction.

Current and emerging neuromodulation therapies for addiction: insight from pre-clinical studies

Neuromodulation therapies such as deep brain stimulation or transcranial magnetic stimulation have shown promise in reducing symptoms of addiction when applied to the prefontal cortex, nucleus accumbens or subthalamic nucleus. Pre-clinical investigations implicate modulation of the cortico-basal ganglia network in these therapeutic effects, and this mechanistic understanding is necessary to optimize stimulation paradigms. Recently, the principle that neuromodulation can reverse drug-evoked synaptic plasticity and reduce behavioral symptoms of addiction has inspired novel stimulation paradigms that have long-term effects in animal models. Pre-clinical studies have also raised the possibility that tailoring neuromodulation protocols can modulate distinct symptoms of addiction. Combining mechanistic knowledge of circuit dysfunction with emerging technologies for non-invasive neuromodulation holds promise for developing therapies for addiction and related disorders.

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.

Response to Deep Brain Stimulation in Three Brain Targets with Implications in Mental Disorders: A PET Study in Rats

Objective

To investigate metabolic changes in brain networks by deep brain stimulation (DBS) of the medial prefrontal cortex (mPFC), nucleus accumbens (NAcc) and dorsomedial thalamus (DM) using positron emission tomography (PET) in naïve rats.

Methods

43 male Wistar rats underwent stereotactic surgery and concentric bipolar platinum-iridium electrodes were bilaterally implanted into one of the three brain sites. [¹⁸F]-fluoro-2-deoxy-glucose-PET (¹⁸FDG-PET) and computed tomography (CT) scans were performed at the 7th (without DBS) and 9th day (with DBS) after surgery. Stimulation period matched tracer uptake period. Images were acquired with a small-animal PET-CT scanner. Differences in glucose uptake between groups were assessed with Statistical Parametric Mapping.

Results

DBS induced site-specific metabolic changes, although a common increased metabolic activity in the piriform cortex was found for the three brain targets. mPFC-DBS increased metabolic activity in the striatum, temporal and amygdala, and reduced it in the cerebellum, brainstem (BS) and periaqueductal gray matter (PAG). NAcc-DBS increased metabolic activity in the subiculum and olfactory bulb, and decreased it in the BS, PAG, septum and hypothalamus. DM-DBS increased metabolic activity in the striatum, NAcc and thalamus and decreased it in the temporal and cingulate cortex.

Conclusions

DBS induced significant changes in ¹⁸FDG uptake in brain regions associated with the basal ganglia-thalamo-cortical circuitry. Stimulation of mPFC, NAcc and DM induced different patterns of ¹⁸FDG uptake despite interacting with the same circuitries. This may have important implications to DBS research suggesting individualized target selection according to specific neural modulatory requirements.