Brain stimulation therapies for neuropsychiatric disease

Recent trends on polycaprolactone as sustainable polymer-based drug delivery system in the treatment of cancer: Biomedical applications and nanomedicine

The unique properties-such as biocompatibility, biodegradability, bio-absorbability, low cost, easy fabrication, and high versatility-have made polycaprolactone (PCL) the center of attraction for researchers. The derived introduction in this manuscript gives a pretty detailed overview of PCL, so you can first brush up on it. Discussion on the various PCL-based derivatives involves, but is not limited to, poly(ε-caprolactone-co-lactide) (PCL-co-LA), PCL-g-PEG, PCL-g-PMMA, PCL-g-chitosan, PCL-b-PEO, and PCL-g-PU specific properties and their probable applications in biomedicine. This paper has considered examining the differences in the diverse disease subtypes and the therapeutic value of using PCL. Advanced strategies for PCL in delivery systems are also considered. In addition, this review discusses recently patented products to provide a snapshot of recent updates in this field. Furthermore, the text probes into recent advances in PCL-based DDS, for example, nanoparticles, liposomes, hydrogels, and microparticles, while giving special attention to comparing the esters in the delivery of bioactive compounds such as anticancer drugs. Finally, we review future perspectives on using PCL in biomedical applications and the hurdles of PCL-based drug delivery, including fine-tuning mechanical strength/degradation rate, biocompatibility, and long-term effects in living systems.

Efficacy and Safety of Electroconvulsive Therapy in Patients With Deep Brain Stimulation: Literature Review, Case Report for Patient With Essential Tremor, and Practical Recommendations

AIM

Deep brain stimulation (DBS) has proven to be an effective therapy of some treatment-resistant psychiatric disorders and movement disorders. Comorbid depressive symptoms are common and difficult to manage. Treatment with electroconvulsive therapy (ECT) may be required. There are few published cases describing the safety and efficacy of ECT for patients with DBS implants, and there are no available guidelines for administration of ECT in patients with DBS and mood disorders. The current study had 3 aims: (i) to conduct a systematic review of case reports on patients with DBS implants who received ECT; (ii) to report the case of a 69-year-old man with a DBS implant for essential tremor, who required ECT; and (iii) to provide practical recommendations for ECT in patients with DBS implants.

METHODS

We conducted a systematic review, in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, of existing case reports on patients with DBS implants administered ECT for psychiatric disorders.

RESULTS

Our search yielded 25 cases of ECT in patients implanted with DBS systems. In addition, we here describe successful ECT management of major depressive disorder in a patient treated by DBS. We also set forth ECT management guidelines based on points of consensus. The 2 most important practical recommendations are to make sure the DBS system is set to 0 V and turned off before ECT, and to avoid sites near the DBS electrodes.

CONCLUSIONS

Electroconvulsive therapy may be an effective and safe treatment for DBS patients with MDD.

Neuromodulation of Gamma-Range Auditory Steady-State Responses: A Scoping Review of Brain Stimulation Studies

Neural oscillations represent a fundamental mechanism that enables coordinated action during normal brain functioning. Auditory steady-state responses (ASSRs) are used to test the ability to generate gamma-range activity. Different non-invasive brain stimulation (NIBS) techniques have the potential to modulate neural activation patterns that are aberrant in a variety of neuropsychiatric disorders. Here, we summarize the current state of knowledge on how different methods of NIBS (transcranial altering current stimulation—tACS, transcranial direct current stimulation—tDCS, transcranial random noise stimulation—tRNS, paired associative stimulation—PAS, repetitive transcranial magnetic stimulation—rTMS) affect the gamma-range ASSRs in both healthy and clinical populations. We show that the current research has been far from systematic and methodologically heterogeneous. Nevertheless, some brain stimulation techniques, especially tACS and rTMS show strong potential for further exploration. We outline the main findings and provide directions for further research into neuromodulation of ASSRs as a promising biomarker of different psychopathological conditions such as schizophrenia, bipolar disorder, attention deficit hyperactivity disorder (ADHD), autism.

Fixed-Life or Rechargeable Battery for Deep Brain Stimulation: A Prospective Long-Term Study of Patient's Preferences

INTRODUCTION

Deep brain stimulation (DBS) is an established treatment for movement disorders. We have previously shown that in our practice, the majority of adult patients prefer fixed-life implantable pulse generators (IPGs), although rechargeable batteries are increasingly used. The aim of this study was to evaluate patients' long-term satisfaction with their choice of battery and factors that influence their decision.

METHODS

Thirty patients with DBS were given a questionnaire to assess long-term satisfaction and experience with the type of battery they had chosen.

RESULTS

Twenty-six patients completed the survey. The mean age was 67.7 ± 7.3 years, and mean follow-up was 18.0 ± 7.2 months. The indications for DBS were Parkinson's disease (76.9%), tremor (11.5%) and dystonia (11.5%). Eleven patients (42.5%) had chosen the rechargeable battery. All patients were still happy with their choices and would not change the type of battery if they had the chance to do so. However, in patients who chose the fixed-life battery, concern about the size of battery rose from 6.7% pre-operatively to 60% on long-term post-operative follow-up. In patients who chose the rechargeable battery, concern about the need to recharge the battery did not change, remaining low postoperatively. Interestingly, even though the main reason cited for choosing the fixed-life battery was the convenience and concern about forgetting to recharge the battery, patients who had chosen a rechargeable IPG did not experience this problem.

CONCLUSION

Patients and caregivers should be involved in the choice of battery, as each type of IPG has its own advantages and disadvantages. Long-term evaluation of patient's experience and satisfaction with battery of choice revealed that size of the IPG, need for further replacement surgeries and need for recharging remain matters of major concern. Although preoperatively often underestimated, the size of the battery seems to be an important factor in long-term satisfaction.

Does hemispheric lateralization influence therapeutic effects of transcranial direct current stimulation?

This study investigated the effect of transcranial direct current stimulation (tDCS) polarity depending on lateralized function of task property in normal individuals performing visuomotor and simple repetitive tasks. Thirty healthy participants with no neurological disorders were recruited to participate in this study. Participants were randomly allocated into active or control condition. For the active condition, tDCS intensity was 2 mA with stimulation applied for 15 minutes to the right hemisphere (tDCS condition). For the sham control, electrodes were placed in the same position, but the stimulator was turned off after 30 seconds (sham condition). The tapping and tracking task tests were performed before and after for both conditions. Univariate analysis revealed significant difference only in the tracking task. For direct comparison of both tasks within each group, the tracking task had significantly higher Z score than the tapping task in the tDCS group (P < 0.05). Thus, our study indicates that stimulation of the right hemisphere using tDCS can effectively improve visuomotor (tracking) task over simple repetitive (tapping) task.

Chronic deep brain stimulation of the medial forebrain bundle reverses depressive-like behavior in a hemiparkinsonian rodent model

Preclinical and clinical evidence suggests that depression might be associated with a dysfunction in the reward/motivation circuitry. Deep brain stimulation (DBS) of the superolateral branch of the medial forebrain bundle (MFB) has been shown in a recent clinical trial to provide a prompt and consistent improvement of depressive symptoms in treatment-resistant patients. In order to better understand the underlying mechanisms of neuromodulation in the context of depression, the effects of chronic bilateral MFB-DBS were assessed in a combined rodent model of depression and Parkinson’s disease. Female Sprague-Dawley rats received unilateral 6-OHDA injection in the right MFB and were divided into three groups: CMS-STIM, CMS-noSTIM and control group. The CMS groups were submitted to chronic unpredictable mild stress (CMS) protocol for 6 weeks. MFB-DBS was applied only to the CMS-STIM group for 1 week. All groups were repeatedly probed on a series of behavioral tasks following each intervention, and to a postmortem histological analysis. CMS led to an increase in immobility in the forced swim test, to a decrease in sucrose solution consumption in the sucrose preference test, as well as to an increased production of ultrasonic vocalizations in the 22 kHz range, indicating increased negative affect. MFB-DBS reversed the anhedonic-like and despair-like behaviors. The results suggest that unilateral dopamine depletion did not preclude MFB-DBS in reversing depressive-like and anhedonic-like behavior in the rodent. Further understanding of the importance of hemispheric dominance in neuropsychiatric disorders is essential in order to optimize stimulation as a therapeutic strategy in these diseases.

60 years of advances in neuropsychopharmacology for improving brain health, renewed hope for progress

Pharmacotherapy is effective in helping many patients suffering from psychiatric and neurological disorders, and both psychotherapeutic and stimulation-based techniques likewise have important roles to play in their treatment. However, therapeutic progress has recently been slow. Future success for improving the control and prevention of brain disorders will depend upon deeper insights into their causes and pathophysiological substrates. It will also necessitate new and more rigorous methods for identifying, validating, developing and clinically deploying new treatments. A field of Research and Development (R and D) that remains critical to this endeavour is Neuropsychopharmacology which transformed the lives of patients by introducing pharmacological treatments for psychiatric disorder some 60 years ago. For about half of this time, the European College of Neuropsychopharmacology (ECNP) has fostered efforts to enhance our understanding of the brain, and to improve the management of psychiatric disorders. Further, together with partners in academia and industry, and in discussions with regulators and patients, the ECNP is implicated in new initiatives to achieve this goal. This is then an opportune moment to survey the field, to analyse what we have learned from the achievements and failures of the past, and to identify major challenges for the future. It is also important to highlight strategies that are being put in place in the quest for more effective treatment of brain disorders: from experimental research and drug discovery to clinical development and collaborative ventures for reinforcing "R and D". The present article sets the scene, then introduces and interlinks the eight articles that comprise this Special Volume of European Neuropsychopharmacology. A broad-based suite of themes is covered embracing: the past, present and future of "R and D" for psychiatric disorders; complementary contributions of genetics and epigenetics; efforts to improve the treatment of depression, neurodevelopmental and neurodegenerative disorders; and advances in the analysis and neuroimaging of cellular and cerebral circuits.

Learning from the past and looking to the future: Emerging perspectives for improving the treatment of psychiatric disorders

Modern neuropsychopharmacology commenced in the 1950s with the serendipitous discovery of first-generation antipsychotics and antidepressants which were therapeutically effective yet had marked adverse effects. Today, a broader palette of safer and better-tolerated agents is available for helping people that suffer from schizophrenia, depression and other psychiatric disorders, while complementary approaches like psychotherapy also have important roles to play in their treatment, both alone and in association with medication. Nonetheless, despite considerable efforts, current management is still only partially effective, and highly-prevalent psychiatric disorders of the brain continue to represent a huge personal and socio-economic burden. The lack of success in discovering more effective pharmacotherapy has contributed, together with many other factors, to a relative disengagement by pharmaceutical firms from neuropsychiatry. Nonetheless, interest remains high, and partnerships are proliferating with academic centres which are increasingly integrating drug discovery and translational research into their traditional activities. This is, then, a time of transition and an opportune moment to thoroughly survey the field. Accordingly, the present paper, first, chronicles the discovery and development of psychotropic agents, focusing in particular on their mechanisms of action and therapeutic utility, and how problems faced were eventually overcome. Second, it discusses the lessons learned from past successes and failures, and how they are being applied to promote future progress. Third, it comprehensively surveys emerging strategies that are (1), improving our understanding of the diagnosis and classification of psychiatric disorders; (2), deepening knowledge of their underlying risk factors and pathophysiological substrates; (3), refining cellular and animal models for discovery and validation of novel therapeutic agents; (4), improving the design and outcome of clinical trials; (5), moving towards reliable biomarkers of patient subpopulations and medication efficacy and (6), promoting collaborative approaches to innovation by uniting key partners from the regulators, industry and academia to patients. Notwithstanding the challenges ahead, the many changes and ideas articulated herein provide new hope and something of a framework for progress towards the improved prevention and relief of psychiatric and other CNS disorders, an urgent mission for our Century.

Deep brain stimulation of the human reward system for major depression--rationale, outcomes and outlook

Deep brain stimulation (DBS) as a putative approach for treatment-resistant depression (TRD) has now been researched for about a decade. Several uncontrolled studies--all in relatively small patient populations and different target regions-have shown clinically relevant antidepressant effects in about half of the patients and very recently, DBS to a key structure of the reward system, the medial forebrain bundle, has yielded promising results within few days of stimulation and at much lower stimulation intensities. On the downside, DBS procedures in regions are associated with surgical risks (eg, hemorrhage) and psychiatric complications (suicidal attenuation, hypomania) as well as high costs. This overview summarizes research on the mechanisms of brain networks with respect to psychiatric diseases and--as a novelty--extrapolates to the role of the reward system in DBS for patients with treatment-resistant depression. It further evaluates relevant methodological aspects of today's research in DBS for TRD. On the scientific side, the reward system has an important yet clearly under-recognized role in both neurobiology and treatment of depression. On the methodological side of DBS research in TRD, better animal models are clearly needed to explain clinical effects of DBS in TRD. Larger sample sizes, long-term follow-up and designs including blinded sham control are required to draw final conclusions on efficacy and side effects. Practical research issues cover study design, patient tracking, and the discussion of meaningful secondary outcome measures.

Intensive HF-rTMS treatment in refractory medication-resistant unipolar depressed patients

BACKGROUND

Major depression is a worldwide severe mental health problem. Unfortunately, not all depressed patients respond to pharmacotherapy or psychotherapy, even when adhering to treatment guidelines. Even though current guidelines do not in particular advocate repetitive Transcranial Magnetic Stimulation (rTMS) in refractory treatment resistant depression (TRD), using more intensive stimulation parameters might hold promise as a valuable alternative.

OBJECTIVE

Consequently, in this randomized sham-controlled crossover study, we wanted to evaluate clinical outcome of intensive HF-rTMS treatment in TRD when applied to the left dorsolateral prefrontal cortex (DLPFC).

METHODS

After a 2-week antidepressant washout, 20 unipolar TRD patients, at least stage III, received 20 sham-controlled high-frequency (HF)-rTMS sessions, in a crossover design. Five daily suprathreshold HF-rTMS sessions were spread over four successive days delivering in total 31,200 stimuli.

RESULTS

Overall, the procedure resulted in immediate statistical significant decreases in depressive symptoms regardless of order/type of stimulation (real/sham), suggesting possible placebo responses. On the other hand, albeit only 35% (7/20) of the patients showed a 50% reduction of their initial Hamilton Depression rating score at the end of the two-week procedure, all these patients showed a prompt clinical response after real HF-rTMS treatment, not after sham. Furthermore, a shorter duration of the current depressive episode was a predictor for beneficial clinical outcome. Unresponsiveness to former ECT could be indicative for negative clinical outcome in these kinds of patients.

LIMITATIONS

Single center setup with relatively small sample size and no follow-up.

CONCLUSIONS

Our findings indicate that intensive HF-rTMS treatment might have the potential to result in fast clinical response when confronted with a refractory TRD patient.

Enhancing performance in numerical magnitude processing and mental arithmetic using transcranial Direct Current Stimulation (tDCS)

The ability to accurately process numerical magnitudes and solve mental arithmetic is of highest importance for schooling and professional career. Although impairments in these domains in disorders such as developmental dyscalculia (DD) are highly detrimental, remediation is still sparse. In recent years, transcranial brain stimulation methods such as transcranial Direct Current Stimulation (tDCS) have been suggested as a treatment for various neurologic and neuropsychiatric disorders. The posterior parietal cortex (PPC) is known to be crucially involved in numerical magnitude processing and mental arithmetic. In this study, we evaluated whether tDCS has a beneficial effect on numerical magnitude processing and mental arithmetic. Due to the unclear lateralization, we stimulated the left, right as well as both hemispheres simultaneously in two experiments. We found that left anodal tDCS significantly enhanced performance in a number comparison and a subtraction task, while bilateral and right anodal tDCS did not induce any improvements compared to sham. Our findings demonstrate that the left PPC is causally involved in numerical magnitude processing and mental arithmetic. Furthermore, we show that these cognitive functions can be enhanced by means of tDCS. These findings encourage to further investigate the beneficial effect of tDCS in the domain of mathematics in healthy and impaired humans.

Neuropsychiatry: where are we and where do we go from here?

Introduction:

Neuropsychiatry has generally been regarded as a hybrid discipline that lies in the borderland between the disciplines of psychiatry and neurology. There is much debate on its current and future identity and status as a discipline.

Materials and Methods:

Taking a historical perspective, the future of neuropsychiatry is placed within the context of recent developments in clinical neuroscience.

Results:

The authors argue that with the maturation of the discipline, it must define its own identity that is not dependent entirely upon the parent disciplines. The requirements for this are the claiming of neuropsychiatric territory, a strong training agenda, an emphasis on treatments that are uniquely neuropsychiatric, and a bold embrace of new developments in clinical neuroscience.

Conclusion:

The exponential growth in neuroscientific knowledge places neuropsychiatry in an excellent position to carve out a strong identity. It is imperative that the leaders of the discipline seize the moment.