High frequency strong current tACS:a new dawn of non-drug therapy for patients with major depressive disorder

A commentary on:Transcranial alternating current stimulation for treating depression:a randomized controlled trial.By Wang H,Wang K,Xue Q,et al.Brain.2022;1451:83-91.doi:10.1093/brain/awab252.Major depressive disorder(MDD)is a common severe mental illness with recurring episodes.The most commonly used treatment is drug therapy,which is associated with a series of side effects and has an efficacy rate below 50%.1 Non-invasive brain stimulation technique has been gradually applied in clinical practice.Transcranial alternating current stimulation(tACS),a form of non-invasive brain stimulation,is a light,wearable piece of equipment for cortical stimulation.It modulates cortical excitability and spontaneous brain activity by applying an electric current to the scalp.

Impact of twice-a-day transcranial direct current stimulation intervention on cognitive function and motor cortex plasticity in patients with Alzheimer's disease

Background Non-invasive brain stimulation has improved cognitive functions in patients with Alzheimer's disease(AD),and some studies suggest a close relationship between cognition and plasticity.However,the clinical benefits of transcranial direct current stimulation(tDCS)in patients still need to be evaluated.Aims This study examined the role of tDCS in improving cognition and whether the improved cognition is related to altered cortical plasticity.Methods 124 patients with AD were randomly assigned to active tDCS(n=63)or sham tDCS(n=61).The tDCS was applied at the dorsolateral prefrontal cortex for 30 treatment sessions across 6 weeks(5 days per week,2 days off).The Mini-Mental State Examination and the Alzheimer's Disease Assessment Scale-Cognitive(ADAS-Cog)were used for cognition evaluation at baseline,week 2 and week 6.The cortical plasticity was represented by motor-evoked potential(MEP)measured with an electromyogram.Results The results showed thatmultiplecourses of active tDcS can improve the cognitive functions of patients with AD,especially in the memory domain(word recall,recall of test instructions and word recognition).In addition,the damaged MEP level was enhanced following active treatment.In the active tDCS group,the improvements in ADAS-Cog total and subitem(word recall and word recognition)scores were negatively correlated with the enhancement of MEP.Conclusions Our research indicates for the first time that twice-a-day tDS may improve the cognitive function of patients with AD.This study also suggests that cognitive dysfunction may be related to impaired cortical plasticity,which warrants mechanistic investigations of the relationship between cognition and plasticity in the future.

Association between SLC17A7 gene polymorphisms and venlafaxine for major depressive disorder in a Chinese Han population:a prospective pharmacogenetic case-control study

Objective: Venlafaxine is a common antidepressant and its therapeutic effect varies among people with different genetic backgrounds. The aim of this study was to investigate whether single nucleotide polymorphisms (SNPs) in theSLC17A7 gene are associated with the treatment outcome of venlafaxine in a Chinese Han population with major depressive disorder.Methods: This prospective pharmacogenetic case-control study that involved genotyping of four SNPs ofSLC17A7 was conducted on 175 major depressive disorder patients of Chinese Han origin, aged 18 to 65 years, participated in the study from April 2005 to September 2006. Comparisons of allele and genotype frequencies of all SNPs were performed between the responder/remission group and the nonresponder/nonremission group. This study was approved by the Institutional Ethics Committee of Sichuan University (approval No. 20151112-265).Results: The allele and genotype frequencies of the four candidate SNPs inSCL17A7 showed no significant difference between responders and nonresponders. Meanwhile, no significant difference was detected in the four investigatedSLC17A7 SNPs between patients who did and did not exhibit remission. Although one of the investigatedSLC17A7 variants (rs1578944) demonstrated a significant association (P=0.022) with a response to venlafaxine after 6 weeks of treatment in the survival analysis, the association was unclear after a Bonferroni multiple comparisons test was conducted.Conclusion: No significant association exists between the four candidate SNPs (rs1043558, rs1320301, rs1578944, and rs74174284) inSLC17A7 and venlafaxine treatment in the Chinese Han population.