[Alexithymia in Multiple Sclerosis - Narrative Review]. / Alexithymie bei Multipler Sklerose ­ eine narrative Übersicht.

Alexithymia is a multidimensional construct of personality implicating difficulties in identifying and describing another's feelings, and externally oriented thinking. It is broadly reported in psychiatric patients but has gained little attention regarding its occurrence and pathophysiology in multiple sclerosis (MS). This narrative review aims to address prevalence, etiology, neurobiological, and clinical findings of alexithymia. The prevalence of alexithymia in MS ranges from 10 to 53%. There seems to be an association with anxiety, depression, fatigue, and some aspects of social cognition, while the relationship with clinical and classical cognitive variables was rarely evaluated. Only a few studies referred to its pathophysiology assuming an aberrant interhemispheric transfer or regional cerebral abnormalities. The prevalence of alexithymia in MS and the potential negative impact on quality of life and interpersonal communication could severely impact clinical MS management and a screnning for these factors should be mandatory. Thus, further evaluation is needed concerning its relationship with clinical, emotional, and cognitive confounders. Large-scale studies employing neuroimaging techniques are needed for a better understanding of the neural underpinnings of this MS feature.

The effects of transcranial direct current stimulation on sleep in patients with multiple sclerosis-A pilot study.

BACKGROUND: Sleep complaints are commonly reported by patients with multiple sclerosis (PwMS). Several pharmacological and alternative interventions have been tried, but are usually faced by limited efficacy. Hence, exploring other methods such as transcranial direct current stimulation (tDCS), might be of interest. The aim of this study was to assess the effects of bifrontal tDCS on subjective (i.e., Epworth Sleepiness Scale (ESS)) and objective sleep measures (i.e., actigraphy). METHODS: Seven patients completed the study. Patients randomly received two blocks of five daily sessions each in a crossover design (active and sham, with a washout interval of three weeks). The anode and cathode were placed over the left and right dorsolateral prefrontal cortices, respectively. Sleep assessment included ESS, sleep onset latency, total sleep duration, time in bed, sleep efficiency, waking after sleep onset, and number of awakenings. RESULTS: Compared to baseline scores (11.14 ± 4.06), significant decrease in ESS was obtained after active intervention (7.86 ± 4.18; p = 0.011), but not after sham intervention (9.57 ± 5.62; p = 0.142). No significant changes were observed with regards to actigraphy measures. Sessions were well tolerated, and no serious side-effects were reported at any time. CONCLUSION: Bifrontal tDCS resulted in significant improvement in daytime sleepiness, but did not yield any effect on objective sleep measures in PwMS. This discrepency might be explained by the modest association that could exist between objective and subjective sleep measures. In addition, it could be assumed that modulating objective sleep measures would require a larger sample size, more stimulation sessions, or modulation of other cortical areas.

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.

Bifrontal transcranial direct current stimulation modulates fatigue in multiple sclerosis: a randomized sham-controlled study.

Fatigue is a frequent and debilitating symptom in patients with central nervous system diseases. Up to 90% of patients with multiple sclerosis (MS) suffer from fatigue that drastically affects the quality of life. MS patients also complain of anxiety and depressive symptoms and these three manifestations tend to cluster together in this clinical population. The objective of this work was to assess the effects of transcranial direct stimulation (tDCS), a noninvasive brain stimulation technique, on fatigue as well as anxiety and depressive symptoms. Eleven fatigued MS patients randomly received two blocks (active and sham tDCS) of five consecutive daily sessions of bifrontal tDCS (anode/cathode over the left/right prefrontal cortices, respectively) in a crossover manner, separated by a 3-week washout interval. Evaluation took place at day 1, day 5 (right after each block) and 1 week later. Active but not sham tDCS resulted in a significant improvement of fatigue at day 5 (p < 0.05), an effect that seems to last at least 1 week following the stimulation (p = 0.05). Active tDCS also significantly improved anxiety symptoms, but the effect emerged 1 week later (p < 0.05). No significant effects were obtained regarding depression (p > 0.05). Bifrontal tDCS seems to modulate fatigue in PwMS. The observed anxiolytic effects could constitute delayed after effects of tDCS or might be mediated by fatigue improvement. These findings merit to be addressed in large-scale controlled trials.