The emerging use of brain stimulation treatments for psychiatric disorders

Efficacy of transcranial alternating current stimulation for schizophrenia treatment: A systematic review

BACKGROUND

Transcranial alternating current stimulation (tACS) is an innovative noninvasive technique in brain stimulation that involves applying a low-intensity electrical current to the scalp. And increasing evidence has revealed its potential in schizophrenia treatment.

OBJECTIVE

This systematic review aimed to evaluate the efficacy of tACS as a novel neurostimulation technique for improving cognitive impairment and alleviating psychotic symptoms in schizophrenia. Additionally, this review attempted to explore the impact of stimulation parameters on the effectiveness of tACS treatment.

METHODS

A systematic literature search was conducted across five databases, including Web of Science, Embase, PubMed, CENTRAL, and PsycINFO, to identify studies investigating the use of tACS in schizophrenia. Only studies that involved the experimental use of tACS in patients with schizophrenia were included in this review.

RESULTS

Nineteen studies were included in this review. The most frequently used current intensities were 2 mA and 1 mA, and the most commonly used frequencies were alpha (10 Hz), theta (4.5 Hz and 6 Hz), and gamma (40 Hz). Some studies showed that tACS may have a potential therapeutic effect by improving cognitive functions in various cognitive domains and/or ameliorating negative symptoms, hallucinations, and delusions in patients with schizophrenia, while others showed no significant change. These studies also implicated that tACS treatment is safe and well tolerated.

CONCLUSIONS

Overall, this systematic review suggests that tACS has promise as a novel, effective, and adjunctive treatment approach for treating schizophrenia. Future research is needed to determine the optimal parameters of tACS for treating this complex disorder.

Psychological Effects of Repetitive Transcranial Magnetic Stimulation on Individuals With Methamphetamine Use Disorder: A Systematic Review and Meta-Analysis

OBJECTIVE

To evaluate the effects of rTMS on drug craving, depression, anxiety, sleep, and cognitive function in methamphetamine (MA) dependent individuals.

DATA SOURCES AND METHODS

Randomized controlled trials (RCTs) of rTMS interventions for MA-dependent patients were searched through PubMed, Embase, Cochrane Library, Web of Science, Chinese National Knowledge Infrastructure (CNKI), Wanfang database, Chongqing Vipers (VIP) and China Biomedical Literature Database (CBLD). The included literature was statistically processed using Revman 5.4, and STATA 16.0 for sensitivity and bias analysis.

RESULTS

A total of 13 papers were included, and the results of the meta-analysis showed that rTMS was effective in reducing craving scores (SMD = -1.53, 95%CI:-2.08 ∼ -0.98, p < 0.00001), improving depression (SMD = -0.32, 95%CI:-0.58 ∼ -0.07, p = 0.01) and sleep scores (WMD = -1.26, 95%CI:-2.26 ∼ -0.27, p = 0.01), but had no effect on anxiety scores (SMD = -0.42, 95%CI:-0.88 ∼ 0.03, p = 0.07); in terms of cognitive function, there were improvements in the international shopping list task (ISL), Groton maze learning task (GML) and continuous paired association learning task (CPAL), except for no effect on the social emotional cognition task (SEC) and two back task (TWOB). Subgroup analysis showed significant differences in the effects of different intervention period on craving in MA-dependent individuals.

CONCLUSION

rTMS was effective in reducing MA dependent individuals' cravings, alleviating depressive symptoms, improving sleep quality and language learning, collaborative learning and executive skills. Due to the small sample size of this study, a large number of RCTs are needed to validate this.

Recent advances in noninvasive brain stimulation for schizophrenia

PURPOSE OF REVIEW

Noninvasive brain stimulation has emerged in the last three decades as a promising treatment for patients with antipsychotic-resistant symptoms of schizophrenia. This review updates the latest progress in the use of noninvasive brain stimulation to treat schizophrenia symptoms.

RECENT FINDINGS

Several recently published randomized-controlled trials support a long-lasting clinical effect of stimulation techniques on schizophrenia symptoms. In addition, efforts have been made in recent months to improve efficacy through several optimization strategies. Studies have tested new parameters of stimulation, such as theta burst stimulation, and alternative cortical or subcortical targets and have reported encouraging results. New forms of electrical stimulations such as alternating and random noise stimulation, have also been studied and have shown clinical and cognitive usefulness for patients. Accelerated stimulation protocols, and prospects could arise with deeper stimulation strategies.

SUMMARY

Using brain stimulation to treat symptoms of schizophrenia seems promising and the great flexibility of the stimulation parameters leaves much room for developing optimization strategies and improving its effectiveness. Further studies need to identify the optimal parameters to maximize response rate.

Targeting temporal parietal junction for assessing and treating disembodiment phenomena: a systematic review of TMS effect on depersonalization and derealization disorders (DPD) and body illusions

The temporal-parietal junction (TPJ) is a key structure for the embodiment, term referred to as the sense of being localized within one's physical body and is a fundamental aspect of the self. On the contrary, the sense of disembodiment, an alteration of one's sense of self or the sense of being localized out of one's physical body, is a prominent feature in specific dissociative disorders, namely depersonalization/derealization disorders (DPD). The aims of the study were to provide: 1) a qualitative synthesis of the effect of Transcranial Magnetic Stimulation (TMS), taking into account its use for therapeutic and experimental purposes; 2) a better understanding on whether the use of TMS could support the treatment of DPD and other clinical conditions in which depersonalization and derealization are displayed. To identify suitable publications, an online search of the PubMed, Cochrane Library, Web of science and Scopus databases was performed using relevant search terms. In addition, an in-depth search was performed by screening review articles and the references section of each included articles. Our search yielded a total of 108 records through multiple databases searching and one additional record was identified through other sources. After duplicates removal, title and abstract reading, we retained 16 records for the assessment of eligibility. According to our inclusion criteria, we retained 8 studies. The selected studies showed that TMS targeting the TPJ is a promising technique for treating disembodiment phenomena DPD and for inducing reversible disembodiment states in healthy subjects. These data represent the first step towards a greater understanding of possible treatments to be used in disembodiment disorders. The use of TMS over the TPJ appears to be promising for treating disembodiment phenomena.

Individualized functional networks reconfigure with cognitive state

There is extensive evidence that functional organization of the human brain varies dynamically as the brain switches between task demands, or cognitive states. This functional organization also varies across subjects, even when engaged in similar tasks. To date, the functional network organization of the brain has been considered static. In this work, we use fMRI data obtained across multiple cognitive states (task-evoked and rest conditions) and across multiple subjects, to measure state- and subject-specific functional network parcellation (the assignment of nodes to networks). Our parcellation approach provides a measure of how node-to-network assignment (NNA) changes across states and across subjects. We demonstrate that the brain's functional networks are not spatially fixed, but that many nodes change their network membership as a function of cognitive state. Such reconfigurations are highly robust and reliable to the extent that they can be used to predict cognitive state with up to 97% accuracy. Our findings suggest that if functional networks are to be defined via functional clustering of nodes, then it is essential to consider that such definitions may be fluid and cognitive-state dependent.

Identity challenges and 'burden of normality' after DBS for severe OCD: a narrative case study

BACKGROUND

Deep Brain Stimulation (DBS) is an emerging and potentially powerful biological treatment for severe Obsessive-Compulsive Disorder (OCD), but the wider impact of the intervention and the sometimes dramatic reduction in symptoms need greater attention in research and practice. The aim of this case study is to explore the subjective experience of preparing for and undergoing DBS as a treatment for severe and treatment-refractory OCD and the experience of the impact of the treatment.

METHODS

This study of subjective experience before and after DBS is based on narrative analysis of two in-depth interviews conducted in November 2014 (1 year after DBS surgery) with a 30-year-old man and his father, utilizing Consolidated Criteria for Reporting Qualitative Studies (COREQ) criteria.

RESULTS

The parallel stories show how OCD posed severe challenges to identity and social milestones, with profound positive and negative impact on the person and family. Yet symptom remission was accompanied by expanded horizons, but also by uncertainty and intense distress associated with the changed identity.

DISCUSSION

The concept of 'burden of normality' is discussed, in light of a treatment experience with DBS for OCD that gives rise to a new array of life challenges and opportunities, with implications for clinical care.

CONCLUSIONS

The concept of burden of normality has, thus far, not extended to evaluations of people who have had DBS for severe OCD and that of their lived experience and recovery trajectory thereafter. This concept highlights that there is work to be done on expectations of normal living and on the transitioning self-concept, in the post-surgical period.

Neuronal networks provide rapid neuroprotection against spreading toxicity

Acute secondary neuronal cell death, as seen in neurodegenerative disease, cerebral ischemia (stroke) and traumatic brain injury (TBI), drives spreading neurotoxicity into surrounding, undamaged, brain areas. This spreading toxicity occurs via two mechanisms, synaptic toxicity through hyperactivity, and excitotoxicity following the accumulation of extracellular glutamate. To date, there are no fast-acting therapeutic tools capable of terminating secondary spreading toxicity within a time frame relevant to the emergency treatment of stroke or TBI patients. Here, using hippocampal neurons (DIV 15-20) cultured in microfluidic devices in order to deliver a localized excitotoxic insult, we replicate secondary spreading toxicity and demonstrate that this process is driven by GluN2B receptors. In addition to the modeling of spreading toxicity, this approach has uncovered a previously unknown, fast acting, GluN2A-dependent neuroprotective signaling mechanism. This mechanism utilizes the innate capacity of surrounding neuronal networks to provide protection against both forms of spreading neuronal toxicity, synaptic hyperactivity and direct glutamate excitotoxicity. Importantly, network neuroprotection against spreading toxicity can be effectively stimulated after an excitotoxic insult has been delivered, and may identify a new therapeutic window to limit brain damage.

Brain Neuromodulation Techniques

The modulation of brain function via the application of weak direct current was first observed directly in the early 19th century. In the past 3 decades, transcranial magnetic stimulation and deep brain stimulation have undergone clinical translation, offering alternatives to pharmacological treatment of neurological and neuropsychiatric disorders. Further development of novel neuromodulation techniques employing ultrasound, micro-scale magnetic fields and optogenetics is being propelled by a rapidly improving understanding of the clinical and experimental applications of artificially stimulating or depressing brain activity in human health and disease. With the current rapid growth in neuromodulation technologies and applications, it is timely to review the genesis of the field and the current state of the art in this area.

Intermittent Theta-Burst Transcranial Magnetic Stimulation Alters Electrical Properties of Fast-Spiking Neocortical Interneurons in an Age-Dependent Fashion

Modulation of human cortical excitability by repetitive transcranial magnetic stimulation (rTMS) appears to be in part related to changed activity of inhibitory systems. Our own studies showed that intermittent theta-burst stimulation (iTBS) applied via rTMS to rat cortex primarily affects the parvalbumin-expressing (PV) fast-spiking interneurons (FSIs), evident via a strongly reduced PV expression. We further found the iTBS effect on PV to be age-dependent since no reduction in PV could be induced before the perineuronal nets (PNNs) of FSIs start to grow around postnatal day (PD) 30. To elucidate possible iTBS-induced changes in the electrical properties of FSIs and cortical network activity during cortical critical period, we performed ex vivo-in vitro whole-cell patch clamp recordings from pre-labeled FSIs in the current study. FSIs of verum iTBS-treated rats displayed a higher excitability than sham-treated controls at PD29-38, evident as higher rates of induced action potential firing at low current injections (100-200 pA) and a more depolarized resting membrane potential. This effect was absent in younger (PD26-28) and older animals (PD40-62). Slices of verum iTBS-treated rats further showed higher rates of spontaneous excitatory postsynaptic currents (sEPSCs). Based on these and previous findings we conclude that FSIs are particularly sensitive to TBS during early cortical development, when FSIs show an activity-driven step of maturation which is paralleled by intense growth of the PNNs and subsequent closure of the cortical critical period. Although to be proven further, rTMS may be a possible early intervention to compensate for hypo-activity related mal-development of cortical neuronal circuits.

Transcranial magnetic stimulation in the treatment of substance addiction

Transcranial magnetic stimulation (TMS) is a noninvasive method of brain stimulation used to treat a variety of neuropsychiatric disorders, but is still in the early stages of study as addiction treatment. We identified 19 human studies using repetitive TMS (rTMS) to manipulate drug craving or use, which exposed a total of 316 adults to active rTMS. Nine studies involved tobacco, six alcohol, three cocaine, and one methamphetamine. The majority of studies targeted high-frequency (5-20 Hz; expected to stimulate neuronal activity) rTMS pulses to the dorsolateral prefrontal cortex. Only five studies were controlled clinical trials: two of four nicotine trials found decreased cigarette smoking; the cocaine trial found decreased cocaine use. Many aspects of optimal treatment remain unknown, including rTMS parameters, duration of treatment, relationship to cue-induced craving, and concomitant treatment. The mechanisms of rTMS potential therapeutic action in treating addictions are poorly understood, but may involve increased dopamine and glutamate function in corticomesolimbic brain circuits and modulation of neural activity in brain circuits that mediate cognitive processes relevant to addiction, such as response inhibition, selective attention, and reactivity to drug-associated cues. rTMS treatment of addiction must be considered experimental at this time, but appears to have a promising future.

Current approaches to treatments for schizophrenia spectrum disorders, part I: an overview and medical treatments

During the last three decades, an increasing understanding of the etiology, psychopathology, and clinical manifestations of schizophrenia spectrum disorders, in addition to the introduction of second-generation antipsychotics, has optimized the potential for recovery from the illness. Continued development of various models of psychosocial intervention promotes the goal of schizophrenia treatment from one of symptom control and social adaptation to an optimal restoration of functioning and/or recovery. However, it is still questionable whether these new treatment approaches can address the patients' needs for treatment and services and contribute to better patient outcomes. This article provides an overview of different treatment approaches currently used in schizophrenia spectrum disorders to address complex health problems and a wide range of abnormalities and impairments resulting from the illness. There are different treatment strategies and targets for patients at different stages of the illness, ranging from prophylactic antipsychotics and cognitive-behavioral therapy in the premorbid stage to various psychosocial interventions in addition to antipsychotics for relapse prevention and rehabilitation in the later stages of the illness. The use of antipsychotics alone as the main treatment modality may be limited not only in being unable to tackle the frequently occurring negative symptoms and cognitive impairments but also in producing a wide variety of adverse effects to the body or organ functioning. Because of varied pharmacokinetics and treatment responsiveness across agents, the medication regimen should be determined on an individual basis to ensure an optimal effect in its long-term use. This review also highlights that the recent practice guidelines and standards have recommended that a combination of treatment modalities be adopted to meet the complex health needs of people with schizophrenia spectrum disorders. In view of the heterogeneity of the risk factors and the illness progression of individual patients, the use of multifaceted illness management programs consisting of different combinations of physical, psychological, and social interventions might be efficient and effective in improving recovery.

Quantifying the effect of repetitive transcranial magnetic stimulation in the rat brain by μSPECT CBF scans

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) is used to treat neurological and psychiatric disorders such as depression and addiction amongst others. Neuro-imaging by means of SPECT is a non-invasive manner of evaluating regional cerebral blood flow (rCBF) changes, which are assumed to reflect changes in neural activity.

OBJECTIVE

rCBF changes induced by rTMS are evaluated by comparing stimulation on/off in different stimulation paradigms using microSPECT of the rat brain.

METHODS

Rats (n = 6) were injected with 10 mCi of (99m)Tc-HMPAO during application of two rTMS paradigms (1 Hz and 10 Hz, 1430 A at each wing of a 20 mm figure-of-eight coil) and sham. SPM- and VOI-based analysis was performed.

RESULTS

rTMS caused widespread significant hypoperfusion throughout the entire rat brain. Differences in spatial extent and intensity of hypoperfusion were observed between both stimulation paradigms: 1 Hz caused significant hypoperfusion (P < 0.05) in 11.9% of rat brain volume while 10 Hz caused this in 23.5%; the minimal t-value induced by 1 Hz was -24.77 while this was -17.98 due to 10 Hz. Maximal percentage of hypoperfused volume due to 1 Hz and 10 Hz was reached at tissue experiencing 0.03-0.15 V/m.

CONCLUSION

High-frequency (10 Hz) stimulation causes more widespread hypoperfusion, while 1 Hz induces more pronounced hypoperfusion. The effect of rTMS is highly dependent on the electric field strength in the brain tissue induced by the TMS coil. This innovative imaging approach can be used as a fast screening tool in quantifying and evaluating the effect of various stimulation paradigms and coil designs for TMS and offers a means for research and development.

Repetitive transcranial magnetic stimulation in combination with citalopram in young patients with first-episode major depressive disorder: a double-blind, randomized, sham-controlled trial

OBJECTIVES

To evaluate the effectiveness of repetitive transcranial magnetic stimulation (rTMS) started with citalopram in first-episode young major depressive patients.

METHODS

In a 2-week double-blind study with a 2-week extended antidepressant phase, 60 first-episode young major depressive patients were randomly assigned to citalopram in combination with 2 weeks of either active or sham rTMS treatment. During the following 2 weeks, the patients continued only the citalopram treatment. The 17-item Hamilton depression rating scale (HAMD-17) and Montgomery-Asberg depression rating scale (MADRS) were used to assess the severity of depression. Moreover, the Wisconsin Card Sorting Test (WCST), Trail-Making Test (TMT), and Stroop Color-Word Test (SCWT) were used to assess executive function.

RESULTS

(1) There was a significantly greater number of early improvers (a reduction of HAMD-17 score ≥ 20% within the first 2 weeks) observed in the active rTMS group compared to the sham group (57% vs. 29%, χ(2)=4.667, p=0.031). (2) There was no significant difference observed in responder rates (46% vs. 36%, χ(2)=0.295, p=0.586) or in remission rates (39% vs. 29%, χ(2)=0.319, p=0.572) between the two groups at 4 weeks. (3) There was a significant difference seen in both HAMD-17 and MADRS scores between the two groups at 2 and 4 weeks. The active rTMS group showed a significantly faster score reduction compared to the sham group at 2 weeks (HAMD-17, t=13.444, p=0.001; MADRS, t=30.123, p=0.000), which was maintained at 4 weeks on both scales (HAMD-17, t=46.915, p=0.000; MADRS, t=39.996, p=0.000). (4) The patients did not deteriorate in executive performance, and even improved in categories on WCST and completed TMT faster in the active group.

CONCLUSIONS

RTMS accelerated the rapidity of the antidepressant response in first-episode young depressive patients. Our results call for future rTMS studies with larger sample sizes, high intensity of stimuli, and longer duration to draw more definitive conclusions.