Resting-state electroencephalographic correlates of cognitive reserve: Moderating the age-related worsening in cognitive function

Repeated application of bifocal transcranial alternating current stimulation improves network connectivity but not response inhibition: a double-blind sham control study

Mounting evidence suggests that transcranial alternating current stimulation can enhance response inhibition, a cognitive process crucial for sustained effort and decision-making. However, most studies have focused on within-session effects, with limited investigation into the effects of repeated applications, which are crucial for clinical applications. We examined the effects of repeated bifocal transcranial alternating current stimulation targeting the right inferior frontal gyrus and pre-supplementary motor area on response inhibition, functional connectivity, and simulated driving performance. Thirty young adults (18-35 yr) received either a sham or transcranial alternating current stimulation (20 Hz, 20 min) across 5 sessions over 2 wk. Resting-state electroencephalography assessed functional connectivity between the pre-supplementary motor area and right inferior frontal gyrus at baseline, the final transcranial alternating current stimulation session, and the 7-d follow-up. Response inhibition was measured using a stop-signal task, and driving performance was assessed before and after the intervention. The results showed significant improvements in functional connectivity in the transcranial alternating current stimulation group between sessions, though response inhibition and driving braking performance remained unchanged. However, while not the targeted behavior, general driving performance potentially improved following bifocal transcranial alternating current stimulation, with participants maintaining stable driving behavior alongside increased spare attentional capacity. These findings suggest that repeated bifocal transcranial alternating current stimulation may enhance cortical connectivity and related cognitive-motor processes, supporting its potential for clinical applications.

VR Cognitive-based Intervention for Enhancing Cognitive Functions and Well-being in Older Adults with Mild Cognitive Impairment: Behavioral and EEG Evidence

Objective: Mild cognitive impairment (MCI) has been recognized as a window of opportunity for therapeutic and preventive measures to slow cognitive decline. The current study investigated the efficacy of the virtual reality (VR) cognitive-based intervention on verbal and visuospatial short-term memory (STM), executive functions (EFs), and wellbeing among older adults with and without MCI. Method: The immersive VR cognitive-based intervention comprised eight 60-minute sessions, held twice a week over a span of 30 days. The participants consisted of 31 non-MCI older adults in the experimental group (mean age ± SD = 66.31 ± 3.12 years), 29 older adults with MCI in the experimental group (mean age ± SD = 68.19 ± 5.03 years), and 30 non-MCI older adults in the control group (mean age ± SD = 64.97 ± 3.35 years). The dependent variables were assessed by using a battery of computerized test, the well-being of older people questionnaire and resting-state EEG. A repeated-measures ANCOVA was employed to examine the effects of the developed VR intervention. Results: Significant improvements were observed in both STMs and EFs following the intervention, as indicated by behavioral and EEG findings, ranging from small to large effect sizes (i.e., = .05-.17). However, enhanced wellbeing was specifically observed among older adults with MCI in the experimental group, F(2, 87) = 6.78, p .01, = .11. Conclusions: The present findings lend support to the efficacy of VR cognitive-based interventions across clinical and non-clinical populations. These results underscore the immediate impact of the intervention across multimodal assessments, including neurophysiological changes, cognitive, and behavioral outcomes.

Cognitive resilience/reserve: Myth or reality? A review of definitions and measurement methods

INTRODUCTION

This review examines the concept of cognitive reserve (CR) in relation to brain aging, particularly in the context of dementia and its early stages. CR refers to an individual's ability to maintain or regain cognitive function despite brain aging, damage, or disease. Various factors, including education, occupation complexity, leisure activities, and genetics are believed to influence CR.

METHODS

We revised the literature in the context of CR. A total of 842 articles were identified, then we rigorously assessed the relevance of articles based on titles and abstracts, employing a systematic approach to eliminate studies that did not align with our research objectives.

RESULTS

We evaluate-also in a critical way-the methods commonly used to define and measure CR, including sociobehavioral proxies, neuroimaging, and electrophysiological and genetic measures. The challenges and limitations of these measures are discussed, emphasizing the need for more targeted research to improve the understanding, definition, and measurement of CR.

CONCLUSIONS

The review underscores the significance of comprehending CR in the context of both normal and pathological brain aging and emphasizes the importance of further research to identify and enhance this protective factor for cognitive preservation in both healthy and neurologically impaired older individuals.

HIGHLIGHTS

This review examines the concept of cognitive reserve in brain aging, in the context of dementia and its early stages. We have evaluated the methods commonly used to define and measure cognitive reserve. Sociobehavioral proxies, neuroimaging, and electrophysiological and genetic measures are discussed. The review emphasizes the importance of further research to identify and enhance this protective factor for cognitive preservation.

Cognitive reserve disorder in age-related hearing loss: cognitive cortical compensatory to auditory perceptual processing

The aim of this study is to ascertain the mechanisms of cognitive reserve disorder in age-related hearing loss (ARHL), to study the correlation between ARHL and cognitive decline via EEG, and to reverse the adverse remodeling of auditory-cognitive connectivity with hearing aids (HAs). In this study, 32 participants were enrolled, including 12 with ARHLs, 9 with HAs, and 11 healthy controls (HCs), to undergo EEG, Pure Tone Average (PTA), Montreal Cognitive Assessment (MoCA), and other general cognitive tests. There were the lowest MoCA in the ARHL group (P = 0.001), especially in language and abstraction. In the ARHL group, power spectral density of the gamma in right middle temporal gyrus was significantly higher than HC and HA groups, while functional connectivity between superior frontal gyrus and cingulate gyrus was weaker than HC group (P = 0.036) and HA group (P = 0.021). In the HA group, superior temporal gyrus and cuneus had higher connectivity than in the HC group (P = 0.036). In the ARHL group, DeltaTM_DTA (P = 0.042) and CTB (P = 0.011) were more frequent than in the HC group, while there was less DeltaTM_CTA (P = 0.029). PTA was found to be associated with MoCA (r = -0.580) and language (r = -0.572), DeltaTM_CTB had a likewise correlation with MoCA (r = 0.483) and language (r = 0.493), while DeltaTM_DTA was related to abstraction (r = -0.458). Cognitive cortexes compensate for worse auditory perceptual processing in ARHL, which relates to cognitive decline. The impaired functional connectivity between auditory and cognitive cortexes can be remodeled by HAs. DeltaTM may serve as a biomarker for early cognitive decline and decreased auditory speech perception in ARHL.