Does transcranial direct current stimulation enhance cognitive performance in Parkinson's disease mild cognitive impairment? An event-related potentials and neuropsychological assessment study.

BACKGROUND: Parkinson's disease-mild cognitive impairment (PD-MCI) is garnering attention as a key interventional period for cognitive impairment. Currently, there are no approved treatments for PD-MCI and encouraging results of transcranial direct current stimulation (tDCS) combined with other interventions have been proposed, though the efficacy and neural mechanisms of tDCS alone have not been studied in PD-MCI yet. OBJECTIVES: The present double-blind, randomized, sham-controlled study assessed the effects of tDCS over the dorsolateral prefrontal cortex on cognitive functions via neuropsychological and electrophysiological evaluations in individuals with PD-MCI for the first time. METHOD: Twenty-six individuals with PD-MCI were administered 10 sessions of active (n = 13) or sham (n = 13) prefrontal tDCS twice a day, for 5 days. Changes were tested through a comprehensive neuropsychological battery and event-related potential recordings, which were performed before, immediately, and 1 month after the administrations. RESULTS: Neuropsychological assessment showed an improvement in delayed recall and executive functions in the active group. N1 amplitudes in response to targets in the oddball test-likely indexing attention and discriminability and NoGo N2 amplitudes in the continuous performance test-likely indexing cognitive control and conflict monitoring increased in the active group. Active stimulation elicited higher benefits 1 month after the administrations. CONCLUSION: The present findings substantiate the efficacy of tDCS on cognitive control and episodic memory, along with the neural underpinnings of cognitive control, highlighting its potential for therapeutic utility in PD-MCI. TRIAL REGISTRATION: NCT 04,171,804. Date of registration: 21/11/2019.

HLA-A, B, C, DRB1 and DQB1 allele and haplotype frequencies in volunteer bone marrow donors from Eastern Region of Saudi Arabia.

We analyzed HLA allele and haplotype frequencies from donors from the Eastern region of Saudi Arabia. A cross-sectional study was performed on 2405 bone marrow donors from the Eastern region. HLA typing was carried out by sequencing. The most common HLA allele groups were HLA-A*02:01:01G (11.08%), A*01:01:01G (10.40%), HLA-B*52:01:01G (8.79%), B*18:01:01G (8.07%), HLA-C*04:01:01G (17.88%), C*12:03:01G (10.23%), HLA-DRB1*10:01 (14.89%), DRB1*03:01:01G (14.10%), HLA-DQB1*02:01:01G (24.53%) and DQB1*05:01:01G (20.17%). The most frequent HLA-A~ C~ B~ DRB1~ DQB1 haplotypes were HLA-A*01:03~ C*15:05:01G~ B*73:01~ DRB1*10:01:01~ DQB1*05:01:01G (3.11%) and HLA-A*01:01:01G~ C*12:02:01G~ B*52:01:01G~ DRB1*15:02:01~ DQB1*06:01:01G (2.25%). When comparing the allele and haplotype frequencies of the Eastern regions' population to those from the Central region we found significant differences in several allele frequencies including A*01:01:01G (P ≤ 0.0001), B*52:01:01G (P ≤ 0.0001), B*18:01:01G (P = 0.0001), C*12:03:01G (P < 0.0001), DRB1*10:01:01 (P < 0.0001) and DQB1*05:01:01G (P < 0.0001). Our data confirms genetic heterogeneity among the Saudi population.