Effects of Transcranial Direct Current Stimulation on Information Processing Speed, Working Memory, Attention, and Social Cognition in Multiple Sclerosis

Multiple Sclerosis (MS) is a chronic inflammatory disease of the central nervous system. Cognitive impairment occurs in 40–65% of patients and could drastically affect their quality of life. Deficits could involve general cognition (e.g., attention and working memory) as well as social cognition. Transcranial direct current stimulation (tDCS), is a novel brain stimulation technique that has been assessed in the context of several neuropsychiatric symptoms, including those described in the context of MS. However, very rare trials have assessed tDCS effects on general cognition in MS, and none has tackled social cognition. The aim of this work was to assess tDCS effects on general and social cognition in MS. Eleven right-handed patients with MS received two blocks (bifrontal tDCS and sham, 2 mA, 20 min, anode/cathode over left/right prefrontal cortex) of 5 daily stimulations separated by a 3-week washout interval. Working memory and attention were, respectively, measured using N-Back Test (0-Back, 1-Back, and 2-Back) and Symbol Digit Modalities Test (SDMT) at the first and fifth day of each block and 1 week later. Social cognition was evaluated using Faux Pas Test and Eyes Test at baseline and 1 week after each block. Interestingly, accuracy of 1-Back test improved following sham but not active bifrontal tDCS. Therefore, active bifrontal tDCS could have impaired working memory via cathodal stimulation of the right prefrontal cortex. No significant tDCS effects were observed on social cognitive measures and SDMT. Admitting the small sample size and the learning (practice) effect that might arise from the repetitive administration of each task, the current results should be considered as preliminary and further investigations in larger patient samples are needed to gain a closer understanding of tDCS effects on cognition in MS

Prefrontal tDCS Decreases Pain in Patients with Multiple Sclerosis

Background: In the last few years, transcranial direct current stimulation (tDCS) has emerged as an appealing therapeutic option to improve brain functions. Promising data support the role of prefrontal tDCS in augmenting cognitive performance and ameliorating several neuropsychiatric symptoms, namely pain, fatigue, mood disturbances, and attentional impairment. Such symptoms are commonly encountered in patients with multiple sclerosis (MS). Objective: The main objective of the current work was to evaluate the tDCS effects over the left dorsolateral prefrontal cortex (DLPFC) on pain in MS patients.Our secondary outcomes were to study its influence on attention, fatigue, and mood. Materials and Methods: Sixteen MS patients with chronic neuropathic pain were enrolled in a randomized, sham-controlled, and cross over study Patients randomly received two anodal tDCS blocks (active or sham), each consisting of three consecutive daily tDCS sessions, and held apart by 3 weeks. Evaluations took place before and after each block. To evaluate pain, we used the Brief Pain Inventory (BPI) and the Visual Analog Scale (VAS). Attention was assessed using neurophysiological parameters and the Attention Network Test (ANT). Changes in mood and fatigue were measured using various scales. Results: Compared to sham, active tDCS yielded significant analgesic effects according to VAS and BPI global scales.There were no effects of any block on mood, fatigue, or attention. Conclusion: Based on our results, anodal tDCS over the left DLPFC appears to act in a selective manner and would ameliorate specific symptoms, particularly neuropathic pain. Analgesia might have occurred through the modulation of the emotional pain network. Attention, mood, and fatigue were not improved in this work. This could be partly attributed to the short protocol duration, the small sample size, and the heterogeneity of our MS cohort. Future large-scale studies can benefit from comparing the tDCS effects over different cortical sites, changing the stimulation montage, prolonging the duration of protocol, and coupling tDCS with neuroimaging techniques for a better understanding of its possible mechanism of action

Noninvasive Brain Stimulation and Psychotherapy in Anxiety and Depressive Disorders: A Viewpoint

Among the most prevalent psychiatric conditions stand anxiety and depression. Psychotherapy and medications are considered effective treatments in these clinical settings. However, pharmacotherapy and psychotherapy (i.e., cognitive behavioral therapy (CBT)) administered in monotherapy or in a combined regimen do not result in satisfactory outcomes in all patients. Therefore, finding new treatments would be of great help. In the last three decades, noninvasive brain stimulation (NIBS) has emerged as a safe tool to improve several neuropsychiatric symptoms. The following work revisits the available reports that assessed the add-on value of NIBS techniques when combined to psychotherapy (CBT or related interventions) in mood and anxiety disorders. The available protocols targeted the prefrontal cortex, a region that was previously found to have an enhanced activity or functional connectivity after psychotherapeutic interventions. Promising yet scarce evidence exists on this matter. A discrepancy exists among the available reports regarding the type and duration of interventions, the patients’ clinical profiles, and the presence of a sham intervention. NIBS may have acted by enhancing psychotherapy effects on the top-down cognitive control of emotions. Combining both therapies may result in promising effects, but future large-scale trials are needed to judge the utility of this combination in psychiatric populations

Disentangling the Neural Basis of Cognitive Behavioral Therapy in Psychiatric Disorders: A Focus on Depression

Background: Major depressive disorder (MDD) stands among the most frequent psychiatric disorders. Cognitive behavioral therapy (CBT) has been shown to be effective for treating depression, yet its neural mechanisms of action are not well elucidated. The objective of this work is to assess the available neuroimaging studies exploring CBT’s effects in adult patients with MDD. Methods: Computerized databases were consulted till April 2018 and a research was conducted according to PRISMA guidelines in order to identify original research articles published at any time in English and French languages on this topic. Results: Seventeen studies were identified. Only one study was randomized comparing CBT to pharmacological interventions, and none included an effective control. Following CBT, changes occurred in cerebral areas that are part of the fronto-limbic system, namely the cingulate cortex, prefrontal cortex and amygdala-hippocampal complex. However, the pattern of activation and connectivity in these areas varied across the studies. Conclusion: A considerable heterogeneity exists with regard to study design, adapted CBT type and intensity, and employed neuroimaging paradigms, all of which may partly explain the difference in studies’ outcomes. The lack of randomization and effective controls in most of them makes it difficult to draw formal conclusion whether the observed effects are CBT mediated or due to spontaneous recovery. Despite the observed inconsistencies and dearth of data, CBT appears to exert its anti-depressant effects mainly by modulating the function of affective and cognitive networks devoted to emotions generation and control, respectively. This concept remains to be validated in large scale randomized controlled trials

Psychiatric event in multiple sclerosis: could it be the tip of the iceberg?

Multiple sclerosis (MS) is a chronic progressive inflammatory disease of the central nervous system. Psychiatric comorbidities are highly prevalent in patients with MS, and can have drastic impact on quality of life and interpersonal relationships. Despite this high prevalence, whether psychiatric manifestations may represent the first signs of MS is still debatable. This constitutes an important issue, since early diagnosis of “psychiatric-onset MS” would result in prompt management, which usually ameliorates long-term prognosis. Here, we discuss clinical and radiological hints that suggest a diagnosis of psychiatric-onset MS. Briefly, this entity should be considered in healthy patients presenting with late-onset psychiatric symptoms, with or without cognitive decline, and with negative family history of psychiatric diseases. A thorough neurological exam is crucial to detect any subtle neurological signs. Brain magnetic resonance imaging is recommended to rule out frontotemporal lesions that might explain the clinical picture. Poor response to standard psychiatric treatments provides additional evidence for the diagnosis of an organic disease (e.g., MS). Combining psychopharmaceuticals with intravenous corticosteroids would result in good outcomes, but patients should be monitored carefully for possible psychiatric exacerbation, a common side effect of steroids

Moral Judgment: An Overlooked Deficient Domain in Multiple Sclerosis?

Multiple sclerosis (MS) is a chronic inflammatory and neurodegenerative disease of the central nervous system through which patients can suffer from sensory, motor, cerebellar, emotional, and cognitive symptoms. Although cognitive and behavioral dysfunctions are frequently encountered in MS patients, they have previously received little attention. Among the most frequently impaired cognitive domains are attention, information processing speed, and working memory, which have been extensively addressed in this population. However, less emphasis has been placed on other domains like moral judgment. The latter is a complex cognitive sphere that implies the individuals’ ability to judge others’ actions and relies on numerous affective and cognitive processes. Moral cognition is crucial for healthy and adequate interpersonal relationships, and its alteration might have drastic impacts on patients’ quality of life. This work aims to analyze the studies that have addressed moral cognition in MS. Only three works have previously addressed moral judgement in this clinical population compared to healthy controls, and none included neuroimaging or physiological measures. Although scarce, the available data suggest a complex pattern of moral judgments that deviate from normal response. This finding was accompanied by socio-emotional and cognitive deficits. Only preliminary data are available on moral cognition in MS, and its neurobiological foundations are still needing to be explored. Future studies would benefit from combining moral cognitive measures with comprehensive neuropsychological batteries and neuroimaging/neurophysiological modalities (e.g., functional magnetic resonance imaging, tractography, evoked potentials, electroencephalography) aiming to decipher the neural underpinning of moral judgement deficits and subsequently conceive potential interventions in MS patients

Brain Stimulation and Neuroplasticity—Series II

Following the great success of the first series of the Special Issue “Brain Stimulation and Neuroplasticity” [...

Effects of Transcranial Direct Current Stimulation on Hand Dexterity in Multiple Sclerosis: A Design for a Randomized Controlled Trial

Background: Cerebellar and motor tracts are frequently impaired in multiple sclerosis (MS). Altered hand dexterity constitutes a challenge in clinical practice, since medical treatment shows very limited benefits in this domain. Cerebellar control is made via several cerebellocortical pathways, of which the most studied one links the cerebellum to the contralateral motor cortex via the contralateral ventro-intermediate nucleus of the thalamus influencing the corticospinal outputs. Modulating the activity of the cerebellum or of the motor cortex could be of help. Method: The main interest here is to evaluate the efficacy of transcranial direct current stimulation (tDCS), a noninvasive brain stimulation technique, in treating altered dexterity in MS. Forty-eight patients will be recruited in a randomized, double-blind, sham-controlled, and crossover study. They will randomly undergo one of the three interventions: anodal tDCS over the primary motor area, cathodal tDCS over the cerebellum, or sham. Each block consists of five consecutive daily sessions with direct current (2 mA), lasting 20 min each. The primary outcome will be the improvement in manual dexterity according to the change in the time required to complete the nine-hole pegboard task. Secondary outcomes will include fatigue, pain, spasticity, and mood. Patients’ safety and satisfaction will be rated. Discussion: Due to its cost-effective, safe, and easy-to-use profile, motor or cerebellar tDCS may constitute a potential tool that might improve dexterity in MS patients and therefore ameliorate their quality of life