Efficacy and safety of simultaneous rTMS-tDCS over bilateral angular gyrus on neuropsychiatric symptoms in patients with moderate Alzheimer's disease: A prospective, randomized, sham-controlled pilot study

BACKGROUND

Treating neuropsychiatric symptoms (NPS) in Alzheimer's disease (AD) remains highly challenging. Noninvasive brain stimulation using repetitive transcranial magnetic stimulation (rTMS) or transcranial direct current stimulation (tDCS) is of considerable interest in this context.

OBJECTIVE

To investigate the efficacy and safety of a novel technique involving simultaneous application of rTMS and tDCS (rTMS-tDCS) over bilateral angular gyrus (AG, P5/P6 electrode site) for AD-related NPS.

METHODS

Eighty-four AD patients were randomized to receive rTMS-tDCS, single-rTMS, single-tDCS, or sham stimulation for 4 weeks, with evaluation at week-4 (W4, immediately after treatment) and week-12 (W12, follow-up period) after initial examination. Primary outcome comprising Neuropsychiatric Inventory (NPI) score and secondary outcomes comprising mini-mental state examination (MMSE), AD assessment scale-cognitive subscale (ADAS-cog), and Pittsburgh sleep quality index (PSQI) scores were collected and analyzed by a two-factor (time and treatment), mixed-design ANOVA.

RESULTS

rTMS-tDCS produced greater improvement in NPI scores than single-tDCS and sham at W4 and W12 (both P < 0.017) and trended better than single-rTMS (W4: P = 0.058, W12: P = 0.034). rTMS-tDCS improved MMSE scores compared with single-tDCS at W4 (P = 0.011) and sham at W4 and W12 (both P < 0.017). rTMS-tDCS also significantly improved PSQI compared with single-rTMS and sham (both P < 0.017). Interestingly, rTMS-tDCS-induced NPI/PSQI improvement was significantly associated with MMSE/ADAS-cog improvement. tDCS- and/or rTMS-related adverse events appeared slightly and briefly.

CONCLUSIONS

rTMS-tDCS application to bilateral AG can effectively improve AD-related NPS, cognitive function, and sleep quality with considerable safety.

The Role of the Dorsolateral Prefrontal Cortex for Speech and Language Processing

This review article summarizes various functions of the dorsolateral prefrontal cortex (DLPFC) that are related to language processing. To this end, its connectivity with the left-dominant perisylvian language network was considered, as well as its interaction with other functional networks that, directly or indirectly, contribute to language processing. Language-related functions of the DLPFC comprise various aspects of pragmatic processing such as discourse management, integration of prosody, interpretation of nonliteral meanings, inference making, ambiguity resolution, and error repair. Neurophysiologically, the DLPFC seems to be a key region for implementing functional connectivity between the language network and other functional networks, including cortico-cortical as well as subcortical circuits. Considering clinical aspects, damage to the DLPFC causes psychiatric communication deficits rather than typical aphasic language syndromes. Although the number of well-controlled studies on DLPFC language functions is still limited, the DLPFC might be an important target region for the treatment of pragmatic language disorders.

Safety Review of Transcranial Direct Current Stimulation in Stroke

OBJECTIVES

The safety, painless, and tolerability features of transcranial Direct Current Stimulation (tDCS) have prompted the research on the therapeutic effects of this technique in stroke; however, an in-depth and unarguable examination of the adverse effects of tDCS in stroke patients is still lacking. This review analyzes the reported adverse effects in stroke, looking for factors that may induce side-effects.

MATERIALS AND METHODS

A comprehensive search of articles published from 1998 to 2015 describing tDCS application in stroke patients performed through data extraction from MEDLINE/PubMed database.

RESULTS

Only 11.62% of published papers reported the occurrence of tDCS adverse effects in stroke patients. The most common was itching (70%), followed by burning sensation (40%), headache (40%), tingling (30%), sleepiness (20%), difficulty of concentration, mild fatigue, skin redness, and dizziness (10%). No significant difference was found between studies "Reporting" vs. "Non-reporting" adverse effects regarding tDCS parameters (intensity, current density, duration of stimulation, and number of sessions).

CONCLUSION

In the majority of stroke patients, tDCS did not induce any severe adverse effect. Regrettably, many published papers did not provide a careful description of exclusion criteria, nor a systematic report of side effects. Our work emphasizes the need of a more meticulous description of the adopted exclusion criteria and of the induced adverse effects, in order to optimize the therapeutic use of tDCS and to better delineate its safety parameters in stroke.

tES Stimulation as a Tool to Investigate Cognitive Processes in Healthy Individuals

Abstract. This paper is aimed at providing an introduction to up-to-date noninvasive brain stimulation tools that have been successful in modulating higher-level cognitive functions in healthy individuals. The current review focuses on transcranial electrical stimulation (tES) studies aiming to explore cognitive models from an experimental rather than clinical viewpoint. It focuses primarily on major advances in language, working memory, learning, response inhibition, and other executive functions in healthy individuals, and the use of different methods of electrical brain stimulation such as transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), and transcranial random noise stimulation (tRNS). The final section summarizes the scientific novelty of the reviewed papers and discusses the possible roles of brain stimulation in future experimental research and clinical applications.