A randomized controlled trial of transcranial direct-current stimulation and cognitive training in children with fetal alcohol spectrum disorder

The effect of transcranial alternating current stimulation on cognitive flexibility and attention of children with intellectual disability: a case report

BACKGROUND

Intellectual disability is a neurodevelopmental disorder characterized by significant impairments in intellectual functioning and adaptive behavior. Cognitive flexibility and attention are crucial cognitive domains often affected in children with intellectual disability. This case report explores the novel use of transcranial alternating current stimulation, a noninvasive brain stimulation technique, to enhance these cognitive functions. The study's novelty lies in its focus on alpha-wave frequency transcranial alternating current stimulation targeting specific Brodmann areas and its potential sustained impact on cognitive flexibility and attention in the pediatric population with intellectual disability.

CASE PRESENTATION

The case study involved two elementary school students, both 7 years old with mild intellectual disability, one male and one female, both with Turkic ethnicity, from Shahid Fahmideh School for Exceptional Children in Khosrowshah, Iran. Both participants underwent a 2-week intervention with daily 20-minute sessions of transcranial alternating current stimulation at an alpha-wave frequency (10 Hz), targeting Brodmann areas F3 and P3. Cognitive flexibility and attention were assessed using the Wisconsin Card Sorting Test and the Clock Test, administered at four time points: pre-intervention, week 1, week 2, and 1 month post-intervention. Statistical analysis showed significant improvements in both Wisconsin Card Sorting Test and Clock Test scores for both participants compared with baseline, with sustained enhancement over time.

CONCLUSION

The findings from this case report indicate that transcranial alternating current stimulation may be a promising intervention for improving cognitive flexibility and attention in children with intellectual disability. The significant and sustained improvements observed suggest that transcranial alternating current stimulation could have a meaningful clinical impact on the cognitive development of this population. However, further research is needed to confirm the efficacy of transcranial alternating current stimulation and to explore its broader applicability and long-term effects in larger, more diverse populations.

Long-term effects of repeated multitarget high-definition transcranial direct current stimulation combined with cognitive training on response inhibition gains

Background

Few studies have investigated the effects of repeated sessions of transcranial direct current stimulation (tDCS) combined with concurrent cognitive training on improving response inhibition, and the findings have been heterogeneous in the limited research. This study investigated the long-lasting and transfer effects of 10 consecutive sessions of multitarget anodal HD-tDCS combined with concurrent cognitive training on improving response inhibition compared with multitarget stimulation or training alone.

Methods

Ninety-four healthy university students aged 18–25 were randomly assigned to undergo different interventions, including real stimulation combined with stop-signal task (SST) training, real stimulation, sham stimulation combined with SST training, and sham stimulation. Each intervention lasted 20 min daily for 10 consecutive days, and the stimulation protocol targeted right inferior frontal gyrus (rIFG) and pre-supplementary motor area (pre-SMA) simultaneously with a total current intensity of 2.5 mA. Performance on SST and possible transfer effects to Stroop task, attention network test, and N-back task were measured before and 1 day and 1 month after completing the intervention course.

Results

The main findings showed that the combined protocol and the stimulation alone significantly reduced stop-signal reaction time (SSRT) in the post-intervention and follow-up tests compared to the pre-intervention test. However, training alone only decreased SSRT in the post-test. The sham control exhibited no changes. Subgroup analysis revealed that the combined protocol and the stimulation alone induced a decrease in the SSRT of the low-performance subgroup at the post-test and follow-up test compared with the pre-test. However, only the combined protocol, but not the stimulation alone, improved the SSRT of the high-performance subgroup. The transfer effects were absent.

Conclusion

This study provides supportive evidence for the synergistic effect of the combined protocol, indicating its superiority over the single intervention method. In addition, the long-term after-effects can persist for up to at least 1 month. Our findings also provide insights into the clinical application and strategy for treating response inhibition deficits.

Efficacy of B-vitamins and vitamin D therapy in improving depressive and anxiety disorders: a systematic review of randomized controlled trials

OBJECTIVES

This systematic review aimed to evaluate the efficacy of B vitamins and vitamin D therapy in improving the standard treatment of depression and anxiety disorders. We also aimed to gather the evidence supporting the recommendations for supplementation in clinical practice.

METHODS

Performed between March 2020 and September 2021, the main inclusion criteria were randomized controlled trials (RCTs), with patients ≥ 18 years old, both sexes, fulfilling target diagnoses of major depressive disorder (MDD), generalized anxiety disorder (GAD), or mild to severe depressive and anxiety symptoms. In addition, the RCTs were included if the scales to assess the severity of the symptoms were standardized rating scales in psychiatric. Trials that reported diagnoses of schizophrenia, perinatal depression, bipolar depression, sleep disorders, eating disorders, cancer, and multiple sclerosis in association with any of the mentioned diagnoses were excluded.

RESULTS

We identified 20 RCTs that matched all eligibility criteria, totaling 2,256 subjects, diagnosed with MDD, GAD, and depressive or anxiety symptoms. Supplementation with folic acid or L-methylfolate, B1, B12 or methylcobalamin, and vitamin D (in different doses and study duration) significantly decreased depression score scales by increasing response to standard pharmacological treatment or as monotherapy, including partial or complete remission. As for anxiety symptoms, the availability of results is limited to adjuvant vitamin D therapy.

DISCUSSION

B vitamins and vitamin D associated with other compounds also showed significant results, so the improvement in symptoms cannot be attributed strictly to those. Our results suggest that intervention with B vitamins and/or vitamin D may be an effective and well-tolerated adjuvant strategy for improving the symptoms of depression and anxiety, according to the patient's clinical status and nutritional biomarkers.

Effects of Anodal Transcranial Direct Current Stimulation on the Primary Motor Cortex in Women With Fibromyalgia: A Randomized, Triple-Blind Clinical Trial

OBJECTIVES

The aim of this study was to analyze the effects of ten sessions of active transcranial direct current stimulation transcranial direct current stimulation (tDCS) (2 mA) with 13:20:13 stimulation at M1 in women with fibromyalgia (FM). To the best of our knowledge, this is the first article that uses this protocol in patients with FM. The main hypothesis is that the protocol would be effective in decreasing pain and that the results would last for up to 90 days.

MATERIALS AND METHODS

This study was a randomized clinical trial with 35 women with FM divided into two groups, active tDCS group and sham tDCS group. A conventional tDCS device was used to deliver 2 mA for 13 minutes, with a 20-minute break followed by a further 13 minutes of stimulation for ten sessions. The anodal stimulus was in the left primary motor cortex M1 region. The primary outcome was a change in the visual analog scale and the Survey of Pain Attitudes pain score at the end of treatment, after 30 days, and 90 days after the end of treatment. Secondary outcomes included changes in the Fibromyalgia Impact Questionnaire, Hamilton Anxiety Rating Scale, Hamilton Depression Rating Scale, World Health Organization's Quality of Life Questionnaire, and Fatigue Assessment Scale. The Research Ethics Committee of the Centro Universitário da Grande Dourados under registration number Certificado de Apresentação de Apreciação Ética approved this research: 36444920.5.0000.5159. The study was registered in The Brazilian Registry of Clinical Trials with the identifier RBR-8wc8rjq.

RESULTS

The active tDCS group showed improvement in pain after ten sessions (p < 0.001), after 30 days (p < 0.01), and after 90 days (p < 0.001) compared with sham tDCS. In addition, improvement in quality of life (QoL) and fatigue was observed in the active tDCS group.

CONCLUSION

The results of this study suggest that active tDCS with an intensity of 2 mA for ten sessions was effective in decreasing pain and fatigue and improving QoL in patients with FM.

Electric Field Strength From Prefrontal Transcranial Direct Current Stimulation Determines Degree of Working Memory Response: A Potential Application of Reverse-Calculation Modeling?

BACKGROUND

Transcranial direct current stimulation (tDCS) for working memory is an enticing treatment, but there is mixed evidence to date.

OBJECTIVES

We tested the effects of electric field strength from uniform 2 mA dosing on working memory change from prestimulation to poststimulation. Second, we statistically evaluated a reverse-calculation method of individualizing tDCS dose and its effect on normalizing electric field at the cortex.

MATERIALS AND METHODS

We performed electric field modeling on a data set of 28 healthy older adults (15 women, mean age = 73.7, SD = 7.3) who received ten sessions of active 2 mA tDCS (N = 14) or sham tDCS (N = 14) applied over bilateral dorsolateral prefrontal cortices (DLPFC) in a triple-blind design. We evaluated the relationship between electric field strength and working memory change on an N-back task in conditions of above-median, high electric field from active 2 mA (N = 7), below-median, low electric field from active 2 mA (N = 7), and sham (N = 14) at regions of interest (ROI) at the left and right DLPFC. We then determined the individualized reverse-calculation dose to produce the group average electric field and measured the electric field variance between uniform 2 mA doses vs individualized reverse-calculation doses at the same ROIs.

RESULTS

Working memory improvements from pre- to post-tDCS were significant for the above-median electric field from active 2 mA condition at the left DLPFC (mixed ANOVA, p = 0.013). Furthermore, reverse-calculation modeling significantly reduced electric field variance at both ROIs (Levene's test; p < 0.001).

CONCLUSIONS

Higher electric fields at the left DLPFC from uniform 2 mA doses appear to drive working memory improvements from tDCS. Individualized doses from reverse-calculation modeling significantly reduce electric field variance at the cortex. Taken together, using reverse-calculation modeling to produce the same, high electric fields at the cortex across participants may produce more effective future tDCS treatments for working memory.

Non-invasive brain stimulation and neuroenhancement

Attempts to enhance human memory and learning ability have a long tradition in science. This topic has recently gained substantial attention because of the increasing percentage of older individuals worldwide and the predicted rise of age-associated cognitive decline in brain functions. Transcranial brain stimulation methods, such as transcranial magnetic (TMS) and transcranial electric (tES) stimulation, have been extensively used in an effort to improve cognitive functions in humans. Here we summarize the available data on low-intensity tES for this purpose, in comparison to repetitive TMS and some pharmacological agents, such as caffeine and nicotine. There is no single area in the brain stimulation field in which only positive outcomes have been reported. For self-directed tES devices, how to restrict variability with regard to efficacy is an essential aspect of device design and function. As with any technique, reproducible outcomes depend on the equipment and how well this is matched to the experience and skill of the operator. For self-administered non-invasive brain stimulation, this requires device designs that rigorously incorporate human operator factors. The wide parameter space of non-invasive brain stimulation, including dose (e.g., duration, intensity (current density), number of repetitions), inclusion/exclusion (e.g., subject's age), and homeostatic effects, administration of tasks before and during stimulation, and, most importantly, placebo or nocebo effects, have to be taken into account. The outcomes of stimulation are expected to depend on these parameters and should be strictly controlled. The consensus among experts is that low-intensity tES is safe as long as tested and accepted protocols (including, for example, dose, inclusion/exclusion) are followed and devices are used which follow established engineering risk-management procedures. Devices and protocols that allow stimulation outside these parameters cannot claim to be "safe" where they are applying stimulation beyond that examined in published studies that also investigated potential side effects. Brain stimulation devices marketed for consumer use are distinct from medical devices because they do not make medical claims and are therefore not necessarily subject to the same level of regulation as medical devices (i.e., by government agencies tasked with regulating medical devices). Manufacturers must follow ethical and best practices in marketing tES stimulators, including not misleading users by referencing effects from human trials using devices and protocols not similar to theirs.

Activation of the anterior cingulate cortex ameliorates anxiety in a preclinical model of fetal alcohol spectrum disorders

People with fetal alcohol spectrum disorders (FASD) are suffered from a wide range of interlinked cognitive and psychological problems. However, few therapeutic options are available for those patients due to limited dissection of its underlying etiology. Here we found that prenatal alcohol exposure (PAE) increases anxiety in mice due to a dysregulated functional connectivity between the anterior cingulate cortex (ACC) and basolateral amygdala (BLA). We also show that chemogenetic activation of excitatory neurons in the ACC reduced this anxiety behavior in the PAE mice. Interestingly, although the level of plasma corticosterone correlated with the increase in anxiety in the PAE, this level was not altered by chemogenetic activation of the ACC, suggesting that the functional connectivity between the ACC and the BLA does not alter the activity of the hypothalamic-pituitary-adrenal axis. Altogether, this study demonstrated that reduced excitation in the ACC is a cause of anxiety in the PAE mice, providing critical insights into the ACC-BLA neural circuit as a potential target for treating anxiety in FASD patients.

Corticostriatal Circuit Models of Cognitive Impairments Induced by Fetal Exposure to Alcohol

The term fetal alcohol spectrum disorder includes a group of diseases caused by fetal alcohol exposure (FAE). Patients with fetal alcohol spectrum disorder display heterogeneous socioemotional and cognitive deficits, particularly in the domain of executive function, that share symptoms with other neuropsychiatric disorders. Despite the availability of several preclinical models, the developmental brain defects causally linked to behavioral deficits induced by FAE remain poorly understood. Here, we first review the effects of FAE on corticostriatal development and its impact on both corticostriatal pathway function and cognitive abilities. We propose three non-mutually exclusive circuit models of corticostriatal dysfunctions to account for some of the FAE-induced cognitive deficits. One model posits that associative-sensorimotor imbalance causes hyper goal-directed behavior, and a second model implies that alteration of prefrontal-striatal behavioral suppression circuits results in loss of behavioral inhibition. A third model suggests that local striatal circuit deficits affect striatal neuronal ensemble function to impair action selection and performance. Finally, we discuss how preclinical approaches applied to these circuit models could offer potential rescue strategies for executive function deficits in patients with fetal alcohol spectrum disorder.

Executive and Social Functioning Across Development in Children and Adolescents With Prenatal Alcohol Exposure

BACKGROUND

Prenatal alcohol exposure (PAE) is linked to a variety of neurodevelopmental challenges, including social functioning (SF) and executive functioning (EF) deficits. These deficits present differently across developmental stages from preschool age to adolescence.

METHODS

The post hoc analyses described here were conducted on data from 83 preschool-age children with PAE (early childhood group; ages 2.5 to 5.0) and 95 adolescents (49 with PAE, 46 controls; ages 8 to 16). Each child completed EF tasks as part of several prior studies. Parents completed social and communication inventories about their child's abilities. Thirty-three participants from the early childhood group returned for a 4-year follow-up and completed both SF and EF measures.

RESULTS

Both the early childhood and adolescent groups with PAE showed deficits in SF and EF. There was a relationship between SF and EF within the adolescent PAE group that was not present in the adolescent control group or the early childhood PAE group. However, at the 4-year follow-up (M_age  = 8.45), participants originally in the early childhood PAE group also demonstrated this relationship.

CONCLUSIONS

These findings support previous research on EF/SF deficits in adolescents with PAE while also addressing a gap in the literature concerning early childhood research on this topic. Additionally, these findings suggest that the relationship between EF and SF deficits may strengthen throughout development. This line of research highlights potential sensitive periods for SF and EF training in children with PAE and suggests that fetal alcohol spectrum disorders programs consider targeting EF training as a component of social skill interventions.