Current Psychiatry Reviews - Volume 14, Issue 4, 2018

Background and Objective: Transcranial direct current stimulation (tDCS) is a safe and cost-effective stimulation technique that has drawn great attention as a potential therapeutic modality for auditory hallucination (AH). This review aims to bring together the evidence from randomized clinical trials (RCTs) on the effectiveness of tDCS for the treatment of AH in schizophrenia. Method: Eligible articles were identified through a comprehensive search of the following electronic databases: PsycINFO, PubMed/MEDLINE, EMBASE, CINAHL, Web of Science, Cochrane Library, and Scopus. PRISMA protocol was used as a guide and totally 7 randomized clinical trials (RCTs) articles were assessed as suitable and included in the review. Results: Seven RCTs that evaluated the effects of tDCS on the severity of AHs in schizophrenic patients were included in this review. Analysis of the outcome measures of these studies pointed toward incongruence in the information with regard to the therapeutic use of tDCS in reducing the severity of auditory hallucinations in schizophrenia. Three RCTs reported a therapeutic benefit, manifested by reductions in severity and frequency of auditory verbal hallucinations in schizophrenic patients. Conclusion: The findings imply that tDCS has shown promising results in reducing the severity of auditory hallucinations in schizophrenic patients, although in some studies, its effect was negligible.

Background and Objective: Preclinical and clinical studies have demonstrated promising therapeutic effects of transcranial direct current stimulation (tDCS) for depressive disorders (DDs). Although food and drug administration has not approved tDCS as a clinical treatment option for DDs, clinical outcomes of the initial studies indicate significant therapeutic efficacy of tDCS which has encouraged further studies to develop this technique as a treatment option for some types of DDs. The present study aims to comprehensively review the therapeutic applications of tDCS in DDs and clinical efficacies of the technique. Method: The databases of PubMed (1980-2018), Web of Sciences (1980-2018), Scopus (1980- 2018), CINAHL (1990-2018), PsycINFO (1990-2018), and Google Scholar (1980-2018) were searched. The searching keywords were "transcranial direct current stimulation" OR "tDCS" AND "depressive disorder" OR "DD" OR "depression" AND "treatment". The clinical trials that assessed the tDCS effects through a cognitive or neurophysiological measure were included in the study. Results: The current evidence shows tDCS, particularly in bifrontal anodal design to be effective in reducing depressive symptoms. In addition to the potential clinical utility and minimal adverseeffects of tDCS, it could improve different behavioral and cognitive functions in DDs patients. Furthermore, the interesting clinical importance of tDCS is its therapeutic efficacy for both treatmentresistant and non-treatment-resistant patients with mild to moderate depression. Conclusion: The clinical trials and metal analyses showed that tDCS is effective as first-line antidepressants. Further studies are needed to reach the exact dose-response profile of tDCS for DDs as well as to identify the mechanisms of actions of antidepressant effects of tDCS.

Introduction: Alzheimer’s disease (AD) is a neurodegenerative pathology manifested by cognitive impairment and behavioral derangement. Transcranial Direct Current Stimulation (tDCS) as non-invasive and safe neuromodulation technique has shown promising effects in different neuropsychiatric disorders. Similarly, tDCS has recently shown potential therapeutic outcomes in AD. The present study aims to systematically review the therapeutic efficacy of tDCS in patients with AD. Method: The databases of PubMed (1970-2017), Web of Sciences (1970-2017), and Google Scholar (1980-2017) were searched using the set terms "tDCS" OR "transcranial direct current stimulation" AND "Alzheimer’s disease" OR "AD" AND "treatment". The search engine Trip Database was used and the date of last search was August 30, 2017. The retrieved records were reviewed Independently by two authors. Results: Seven studies were obtained with a total of 185 patients who met the inclusion criteria. Evaluating the results, 4 studies supported the possible efficacy of the therapy versus 3 that did not find statistically significant differences compared with the placebo groups. Anodal tDCS over frontal cortex, particularly left dorsolateral prefrontal cortex and temporal cortex, showed therapeutic efficacy in AD. Conclusion: Further studies are needed to determine effective protocols and clinical efficacy of tDCS for AD treatment. However, the current evidence from clinical trials encourages further research to investigate anodal tDCS as an adjuvant treatment for patients with AD.

Background and Objective: Attention deficit hyperactivity disorder (ADHD) is a common neuropsychiatric disorder. The current pharmaceutical treatments are associated with side effects and with low efficacy so that about one third of the adults do not respond to these treatments. Transcranial direct current stimulation (tDCS) is a non-invasive and safe brain modulation technique with promising therapeutic effects on ADHD symptoms. This paper aims to comprehensively review the clinical trials of tDCS conducted in humans for the treatment of ADHD. We aim to review the clinical efficacy and mechanisms of action of the technique in ADHD treatment. Method: The databases of PubMed (1990-2017), Web of Sciences (1990-2017), Google Scholar (1990-2017) and Scopus (1990-2017) were searched using the keywords “Attention deficit hyperactivity disorder” OR “ADHD” AND “Transcranial direct current stimulation” OR “tDCS” AND "treatment" AND "mechanism". The title and abstract of the papers were reviewed by at least two authors and the relevant papers were selected for in depth review. We selected the preclinical and clinical trials that studied the effects of tDCS on ADHD patients through measuring behavioral, hemodynamic, or neurophysiological features. Results: The current evidence supports the therapeutic efficacy of tDCS in the improvement of ADHD, but, the findings are controversial. Anodal tDCS seems to be more effective than cathodal in ADHD. In addition, the appropriate sites of stimulation are frontal cortex in particular left dorsolateral prefrontal cortex and right inferior frontal gyrus. The tDCS can improve inhibitory control and interference control in ADHD patients. Conclusion: tDCS has shown promising but limited clinical efficacy for ADHD treatment. However, the current evidence supports continuing the preclinical and clinical studies to determine physiological mechanisms and dose response of tDCS in ADHD to establish a clinical protocol.

Background and Objective: Addiction is one of the main health issues worldwide. Severe side effects and nonspecific actions of conventional medications have necessitated the development of new safe and non-invasive modality for addiction treatment. Transcranial direct current stimulation (tDCS) has shown potential treatment effects in substance use disorder and addiction. The present study aims to review the clinical trials on the effects of tDCS for treatment of addiction and discusses the therapeutic efficacy of the technique. Method: The databases of PubMed (1980-2018), Web of Sciences (1980-2018), Scopus (1980- 2018), CINAHL (1990-2018), and PsycINFO (1990-2018) were searched using the set terms. The titles and abstracts of all the retrieved records in the searching step were carefully reviewed by two authors and the relevant papers with full texts available were collected for further assessments. The date of the last search was 20 May, 2018. The language of the search was English and only records in English were included in the study. The clinical trials with randomized controlled design were included. The addictions to cocaine, alcohol, crack cocaine, heroin, methamphetamine, and nicotine were included in the study. Results: Twenty-three clinical trials were selected for full analysis. Five were on alcohol, 8 on nicotine, 5 on crack-cocaine, 1 on heroin, 1 on cocaine, 1 on marijuana, 1 on methamphetamine, and 1 two-arm trial simultaneously assessed alcohol and crack-cocaine. The main targets were dorsolateral prefrontal cortex (DLPFC) and FPT regions and the effective electrodes montage was bilateral (anode/cathode over left/right or right/left) DLPFC and dual cathodal on FPT regions. Most of the RCTs showed both polarities in bilateral DLPFC are effective in improving symptoms of addictions, however, for specific types of addictions, we observed the polarity-dependent treatment response. For crack-cocaine, we observed polarity dependent outcome where cathodal DLPFC (cathode over left/anode over right) showed greater therapeutic efficacy than the opposite polarity. In contrary, for alcohol, nicotine addictions both polarities of bilateral DLPFC showed significant therapeutic outcomes. Conclusion: The current literature shows that tDCS, particularly over DLPFC and FPT areas, may have therapeutic effects in addictions, though the studies are few and suffer heterogeneous methodology and protocols. However, further studies with greater sample size and longer follow up should be conducted to reach a definitive conclusion on the efficacy of tDCS for addictions.

Background and Objective: Transcranial direct current stimulation (tDCS) has shown therapeutic efficacy in different psychiatric disorders including depression, attention deficit hyperactivity disorder (ADHD), cognitive functions in healthy subjects have made this technique an interesting research option for developing non-medication techniques for a variety of psychiatric disorders. This paper aimed to comprehensively review the therapeutic applications of tDCS in psychiatric disorders. Method: The databases of PubMed (1985-2018), EMBASE (1985-2018), Web of Sciences (1985- 2018), PsycINFO (1980-2018) and Google Scholar (1980-2018) were searched using the search terms "transcranial direct current stimulation" OR "tDCS" AND "psychiatric disorders" OR “neuropsychiatric disorders” AND "treatment" AND “efficacy”. The retrieved records were screened for the title and abstract by two authors and the relevant papers were reviewed for further details. The applications of tDCS in the disorders with promising outcomes are discussed. Results: TDCS has shown therapeutic effects in different neuropsychiatric disorders such as major depression, attention deficit hyperactivity disorder (ADHD), schizophrenia, Alzheimer disease (AD), tinnitus, obsessive compulsive disorder, hallucinations, and substance abuse. The clinical efficacy for major depression, ADHD, schizophrenia, and tinnitus is more promising. This may be partly because more studies have been conducted on these disorders than the other disorders. For depression tDCS shows treatment efficacy comparable with the first generation antidepressive pharmacological drugs. Anodal tDCS over prefrontal cortex (PFC) was the most used protocol for major depression. The anodal tDCS over frontal cortex and right inferior frontal gyrus show promising therapeutic effects in ADHD. For tinnitus the most frequent used protocols are bifrontal and bilateral tDCS applied over dorsolateral PFC and auditory cortex. Anodal tDCS over frontal cortex particularly LDLPFC and temporal cortex showed therapeutic efficacy in AD. For schizophrenia, tDCS has shown effectiveness in reducing the disease’s symptoms ranging from auditory hallucinations which the effects were the most marked to working memory, learning, negative and cognitive symptoms. The frequently used sites of stimulation were PFC and temporal cortex. Conclusion: The current evidence showed the therapeutic efficacies of tDCS as adjunctive or alternative treatment option for different neuropsychiatric disorders. TDCS due to its safe and cost-effective profile could be developed for symptoms amelioration or at least cognitive enhancement in these disorders. However, further studies with big sample size should be conducted to develop effective protocol for each disorder as well as understanding the mechanisms of action of tDCS in neuropsychiatric disorders.

Background: Developing group of recent findings demonstrate that serotonin receptors play a significant pathophysiological role in major depressive disorder (MDD). Objective: This article will briefly review the literature concerning mechanisms of action, brain distribution and localization of 5HT receptor subtypes and their changes in patients with MDD, as reported via neuroimaging, postmortem and genetic studies. Method: Postmortem brain researches, neuroimaging PET studies and genetic polymorphism studies in suicide and depression were examined in order to explore the role of 5-HT receptor subtypes in the neurobiology of major depression as possibly beneficial biomarkers for diagnosis and treatment response in MDD. Results: Reported significant association between Gene polymorphisms of 5-HT receptors including 5-HT1A, 5-HT1B, 5-HT3, 5HT4 and 5HT6 and diagnosis and treatment response in depression suggests these serotonin receptor subtypes as important therapeutic and diagnostic markers for depression. Neuroimaging studies by PET revealed a higher rostrally and lower caudally binding potential of 5-HT1A receptor in the dorsal raphe nucleus in patients with suicidal depression, decreased potential binding of 5-HT1B receptor and elevated binding potential of cortical 5-HT2A receptors. Postmortem studies reported an elevated abundance of 5-HT2A receptors in the prefrontal cortex, altered mRNA encoding editing of 5-HT2C receptors in the prefrontal cortex and higher levels of 5HT4 receptor binding in frontal cortex and caudate nucleus of depressed suicide victims. Conclusion: 5-HT receptors including 5-HT1A, 5-HT1B, 5-HT2A, 5-HT2C, 5-HT3, 5-HT4 and 5- HT6 are involved in the neurobiology of major depression and might be beneficial biomarkers for diagnosis and treatment response in MDD and will help the development of future treatments.

Background: Crisis as a topic in mental health is more relevant than ever. There are rapid changes happening in the world, involving politics, education, migration and so on. All these new events have consequences over mental health, at the short and long terms. Objective: Accomplish the need to understand the neuronal mechanisms underlying an illness after a crisis event, as well as a better guidance of the therapeutic intervention. Method: This article is a review of crisis and the consequent illness that it can originate. It consists of a brief presentation of the main contributions of several authors in their theoretical and practical components, from their starting point in the development of Crisis Theory. The review continues in a presentation of the correlations between the perpetuation of crisis and consequent mental illness, describing the known neurocircuitry underlying the anxious and depressive outcomes. The neurobiological connection between crisis and mental illness with psychotherapeutic intervention is discussed. Results: The present neuroscientific data allow the understanding of how the brain can work defining behavior, judgement or decision making. The knowledge of the neurobiology involved is increasingly relevant in this area, as it is in others that involve mental illness. Conclusion: As neuroscience progresses, neurobiology and neurocircuitry can provide the unifying language and the explanation to the processes involved in mental health and disease, permitting the use of psychotherapeutic techniques with more benefits to the patient.

Background: Drug abuse is one of the major concerns of human societies. The relapse of abusing drugs is one of the main targets of addiction therapies. Studies in this regard have introduced four basic mechanisms: 1) drug-induced reinforcement 2) cue-induced reinforcement 3) stress-induced reinforcement and 4) negative reinforcement. Objective: In recent studies, cognition has got great interest in addiction research. It has been proposed that prefrontal cortex can reduce the risk of relapse, by influencing cognition. In this review, we are going to discuss the benefit of better cognition in the context of the above four basic mechanisms, not specifically prefrontal cortex. Method: A literature search was conducted in all major indexing databases including Pubmed, Embase and Google Scholar. The included articles were not limited to the time of publication and all relevant articles were used. Results: Our findings suggest that cognition is necessary for controlling drug abuse. Also, it was found that cognition may control relapse to drug abuse by influencing the four basic mechanisms that are responsible for relapse to drugs. Conclusion: Cognition is a necessary factor for controlling drug abuse. It suggested paying special attention to cognition before implementing a plan for treatment of relapse to drug abuse.