Executive function deficits in mild cognitive impairment: evidence from saccade tasks

Global trends and prospects of ocular biomarkers in Alzheimer's disease: a bibliometric analysis

Background

Alzheimer's disease (AD) diagnosis necessitates the development of novel biomarkers that ensure high diagnostic accuracy and cost-effectiveness in blood tests. Recent studies have identified a significant association between ocular symptoms and the pathological processes of AD, suggesting the potential for effective ocular biomarkers. This bibliometric analysis aims to explore recent advancements and research trends in ocular biomarkers for the early diagnosis of AD.

Methods

Articles related to AD and ocular biomarkers were retrieved from the Web of Science Core Collection (WoSCC) database. These articles were analyzed using bibliometric tools such as VOSviewer, R-bibliometrix, and CiteSpace.

Results

A total of 623 papers were included in the analysis, revealing a steady increase in publications since 2012. The United States produced the most publications, followed by China and Italy. Notably, authors affiliated with Complutense University of Madrid in Spain and Sapienza University of Rome in Italy made significant contributions, demonstrating robust internal collaborations. The Journal of Alzheimer's Disease published the most articles pertaining to ocular science and neuroscience. Keyword analysis indicates evolving trends in ocular markers for AD from 2005 to 2024, transitioning from diagnostic techniques (e.g., "spectroscopy," "cerebrospinal fluid") to pathological mechanisms (e.g., "oxidative stress") and advanced imaging technologies (e.g., "optical coherence tomography angiography").

Conclusion

The bibliometric analysis highlights key research hotspots related to ocular markers for AD, documenting the shift from basic diagnostic techniques to advanced imaging methods and the discovery of novel biomarkers. Future research may investigate the potential of Optical Coherence Tomography Angiography, tear component analysis, eye movement assessments, and artificial intelligence to enhance early detection of AD.

Cognitive gains and cortical thickness changes after 12 weeks of resistance training in older adults with low and high risk of mild cognitive impairment: Findings from a randomized controlled trial

BACKGROUND

In this randomized controlled trial, we assessed the neuroprotective effect of a 12-week resistance training (RT) program on executive control and cortical thickness of the prefrontal, temporal, parietal, and central cortex, regions prone to structural decline in individuals with mild cognitive impairment (MCI).

METHODS

Seventy older adults (aged 60-85 y old, 38 females and 32 males) were randomly allocated to a 12-week lower limb RT program or a waiting list control group. The Montreal Cognitive Assessment (MoCA) was used to stratify participants screened for high (< 26) or low (≥ 26) MCI risk. Cognitive measurements consisted of the two-choice reaction time, Go/No-go, mathematical processing, and memory search tests. Cortical thickness was estimated from 3D T1-weighted MR images.

RESULTS

Complete randomized controlled trial data was obtained from 50 individuals (24 with high MCI risk). Significant Group x Time interactions were found for response on the Go/No-go task and cortical thickness of the right parahippocampal gyrus [F ≥ 5.3, p ≤ 0.03; η2p ≥ 0.12]. An inspection of these observations revealed an increase in cortical thickness (+1.18 %) and a decrease in response time (-4.35 %) in individuals with high MCI risk allocated to the exercise group (both uncorrected p = 0.08). Decreased response time on the Go/No-go task was associated with increased cortical thickness in the right entorhinal gyrus (uncorrected p = 0.01).

CONCLUSIONS

Our study demonstrated that 12 weeks of RT intervention may effectively improve cognitive performance and slow neuronal loss in the hippocampal complex of older adults at high MCI risk. Findings support evidence for the neuroprotective effects of resistance training and its potential role in cognitive health.

Analysis of eye movement features in patients with Alzheimer's disease based on intelligent eye movement analysis and evaluation system

BACKGROUND

The early identification of Alzheimer's disease (AD) benefits patients, so creating a simple and convenient method is crucial for diagnosing early symptoms.

OBJECTIVE

To offer a potential approach for the early detection of both AD and mild cognitive impairment (MCI).

METHODS

Eye movement data from 66 patients were divided into three groups, including healthy control group (HC), MCI group, and AD group. We searched for parameters that can detect MCI at an early stage and drew receiver operating characteristic (ROC) curves. The correlation between eye movement parameters and cognitive scores was analyzed.

RESULTS

The MCI group differed from the HC group in error correction rate of antisaccade (p = 0.008) and total offset degrees (>4°) (p = 0.011) of lateral fixation. The AD group had different overlap prosaccade accuracy (p = 0.025), latency (p = 0.009) and average completion time (p = 0.015), gap prosaccade latency (p = 0.005) and average completion time (p = 0.005), antisaccade accuracy (p = 0.006), error correction rate (p < 0.001) and average saccade velocity (p = 0.035), and lateral fixation accuracy (p = 0.018), total offset degrees (>4°) (p = 0.041) compared to the HC group. The AD group differed significantly from the MCI group in accuracy (p = 0.001) and error correction rate (p = 0.044) of antisaccades, the latency (p = 0.009) and average completion time (p = 0.025) of overlap prosaccade and the latency (p = 0.038) of gap prosaccade, these parameters can serve as indicators to monitor the progress of the disease. Lateral fixation combined with antisaccade was more conducive to identifying MCI patients with the area under the ROC curve of 0.837. Most eye movement parameters had a light to moderate correlation with cognitive scores.

CONCLUSIONS

Eye movements can be used for early identification of MCI/AD patients and to monitor disease progression.

Abnormal eye movements: relationship with clinical symptoms and predictive value for Alzheimer's disease

Background

Abnormal eye movements occur at the early stages of Alzheimer's disease (AD). However, the characteristics of abnormal eye movements of patients with AD and their relationship with clinical symptoms remain inconsistent, and their predictive value for diagnosing and monitoring the progression of AD remains unclear.

Methods

A total of 42 normal controls, 63 patients with mild cognitive impairment due to AD (AD-MCI), and 49 patients with dementia due to AD (AD-D) were recruited. Eye movements were assessed using the EyeKnow eye-tracking and analysis system. Cognitive function, neuropsychiatric symptoms, and activities of daily living were evaluated using various rating scales, and correlation analyses and receiver operating characteristic curves were performed.

Results

Patients with AD exhibited increased number of offsets and offset degrees, prolonged offset duration, and decreased accuracy in lateral fixation; reduced accuracy, prolonged saccadic duration, and decreased velocity in prosaccade; decreased accuracy and corrected rate, prolonged corrected antisaccadic duration, and reduced velocity in antisaccade; and reduced accuracy and increased inhibition failures in memory saccade. Eye movement parameters were correlated with global cognition and the cognitive domains of memory, language, attention, visuospatial ability, execution function, and activities of daily living. Subgroup analysis indicated that the associations between eye movements and clinical symptoms in patients with AD were influenced by disease severity and history of diabetes. In the AD-D and AD with diabetes groups, these associations diminished. Nevertheless, the associations persisted in the AD-MCI and AD without diabetes groups. The areas under the curves for predicting AD, AD-MCI, and AD-D were 0.835, 0.737, and 0.899, respectively (all p < 0.05).

Conclusion

Patients with AD exhibit distinct patterns of abnormal eye movements. Abnormal eye movements are significantly correlated with global cognition, multiple cognitive domains, and activities of daily living. Abnormal eye movements have a considerable predictive value for the diagnosis and progression of AD.

Molecular physiology unlocks the mystery that relates cognitive impairment with the retina in schizophrenia and autism spectrum disorders: a perspective review

Schizophrenia and Autism spectrum disorders (SSD and ASD) are neurodevelopmental disorders involving cognitive impairment. Timely diagnosis is important for early intervention; currently, no tools are available to help with early diagnosis. Molecular biomarkers of cognitive impairment have been extensively studied, but clinical correlation is crucial in screening for cognitive impairment in SSD and ASD. There has been growing interest in examining the retina to scan for neurological disorders since the retina is the only part of the central nervous system that can be directly imaged non-invasively and in a timely manner. This review discusses biomarkers of cognitive impairment and their correlation to the retina in SSD and ASD. It also discusses the possible involvement of the retina and molecular biomarkers, specifically Disintegrin and metalloproteinase domain-containing protein 10 (ADAM10) and ciliary neurotrophic factor (CNTF) in the pathophysiology of SSD and ASD. A protocol for early diagnosing cognitive impairment and its severity in SSD and ASD is also suggested. This review also mentions insights into the potential use of molecular biomarkers of cognitive impairment to enhance cognitive performance in ASD and SSD and areas where more research is needed to solve the mystery of the relationship between the retina and cognitive impairment in neurodevelopmental psychiatric disorders.

Eye-tracking training improves visuospatial working memory of children with attention-deficit/hyperactivity disorder and autism spectrum disorder

Given the close connection between eye movement and frontal lobe functions and some evidence supporting the effect of eye-tracking training on enhancing cognitive performance mediated by the frontal lobe, this study aimed to explore if after-school eye-tracking training can improve the visuospatial working memory (VSWM) and cognitive flexibility performance in children with attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD). This study is a non-randomized cluster trial. Forty children from eight primary schools were selected, half receiving eye-tracking training for 20 sessions over 9 months, while the other half served as a waitlist control. They were matched on demographic characteristics and baseline cognitive performance. Their VSWM and cognitive flexibility were assessed at the beginning and end of the study. Results showed that children who received eye-tracking training, but not those on a waitlist, exhibited significant improvements in the total score and working memory span of the VSWM tests, and the correct responses in cognitive flexibility tests. Specifically, VSWM performance at higher span levels (5 or above) yielded a greater improvement. The findings suggest that eye-tracking training can be a feasible and effective after-school program for improving working memory and cognitive flexibility performance in children with ADHD and ASD. This study was prospectively registered at ClinicalTrials.gov (https://clinicaltrials.gov/, trial number: NCT05428657).

An effective screening model for subjective cognitive decline in community-dwelling older adults based on gait analysis and eye tracking

Objective

To evaluate the effectiveness of multimodal features based on gait analysis and eye tracking for elderly people screening with subjective cognitive decline in the community.

Methods

In the study, 412 cognitively normal older adults aged over 65 years were included. Among them, 230 individuals were diagnosed with non-subjective cognitive decline and 182 with subjective cognitive decline. All participants underwent assessments using three screening tools: the traditional SCD9 scale, gait analysis, and eye tracking. The gait analysis involved three tasks: the single task, the counting backwards dual task, and the naming animals dual task. Eye tracking included six paradigms: smooth pursuit, median fixation, lateral fixation, overlap saccade, gap saccade, and anti-saccade tasks. Using the XGBoost machine learning algorithm, several models were developed based on gait analysis and eye tracking to classify subjective cognitive decline.

Results

A total of 161 gait and eye-tracking features were measured. 22 parameters, including 9 gait and 13 eye-tracking features, showed significant differences between the two groups (p < 0.05). The top three eye-tracking paradigms were anti-saccade, gap saccade, and median fixation, with AUCs of 0.911, 0.904, and 0.891, respectively. The gait analysis features had an AUC of 0.862, indicating better discriminatory efficacy compared to the SCD9 scale, which had an AUC of 0.762. The model based on single and dual task gait, anti-saccade, gap saccade, and median fixation achieved the best efficacy in SCD screening (AUC = 0.969).

Conclusion

The gait analysis, eye-tracking multimodal assessment tool is an objective and accurate screening method that showed better detection of subjective cognitive decline. This finding provides another option for early identification of subjective cognitive decline in the community.

A portable and efficient dementia screening tool using eye tracking machine learning and virtual reality

Dementia represents a significant global health challenge, with early screening during the preclinical stage being crucial for effective management. Traditional diagnostic biomarkers for Alzheimer's Disease, the most common form of dementia, are limited by cost and invasiveness. Mild cognitive impairment (MCI), a precursor to dementia, is currently identified through neuropsychological tests like the Montreal Cognitive Assessment (MoCA), which are not suitable for large-scale screening. Eye-tracking technology, capturing and quantifying eye movements related to cognitive behavior, has emerged as a promising tool for cognitive assessment. Subtle changes in eye movements could serve as early indicators of MCI. However, the interpretation of eye-tracking data is challenging. This study introduced a dementia screening tool, VR Eye-tracking Cognitive Assessment (VECA), using eye-tracking technology, machine learning, and virtual reality (VR) to offer a non-invasive, efficient alternative capable of large-scale deployment. VECA was conducted with 201 participants from Shenzhen Baoan Chronic Hospital, utilizing eye-tracking data captured via VR headsets to predict MoCA scores and classify cognitive impairment across different educational backgrounds. The support vector regression model employed demonstrated a high correlation (0.9) with MoCA scores, significantly outperforming baseline models. Furthermore, it established optimal cut-off scores for identifying cognitive impairment with notable sensitivity (88.5%) and specificity (83%). This study underscores VECA's potential as a portable, efficient tool for early dementia screening, highlighting the benefits of integrating eye-tracking technology, machine learning, and VR in cognitive health assessments.

A glimpse into the future: revealing the key factors for survival in cognitively impaired patients

Background

Drawing on prospective data from the National Health and Nutrition Examination Survey (NHANES), our goal was to construct and validate a 5-year survival prediction model for individuals with cognitive impairment (CI).

Methods

This study entailed a prospective cohort design utilizing information from the 2011-2014 NHANES dataset, encompassing individuals aged 40 years or older, with updated mortality status as of December 31, 2019. Predictive models within the derivation and validation cohorts were assessed using logistic proportional risk regression, column-line plots, and least absolute shrinkage and selection operator (LASSO) binomial regression models.

Results

The study enrolled a total of 1,439 participants (677 men, mean age 69.75 ± 6.71 years), with the derivation and validation cohorts consisting of 1,007 (538 men) and 432 (239 men) individuals, respectively. The 5-year mortality rate stood at 16.12% (n = 232). We devised a 5-item column-line graphical model incorporating age, race, stroke, cardiovascular disease (CVD), and blood urea nitrogen (BUN). The model exhibited an area under the curve (AUC) of 0.772 with satisfactory calibration. Internal validation demonstrated that the column-line graph model displayed strong discrimination, yielding an AUC of 0.733, and exhibited good calibration.

Conclusion

To sum up, our study successfully developed and internally validated a 5-item nomogram integrating age, race, stroke, cardiovascular disease, and blood urea nitrogen. This nomogram exhibited robust predictive performance for 5-year mortality in individuals with CI, offering a valuable tool for prognostic evaluation and personalized care planning.

Anti-saccade as a tool to evaluate cognitive impairment in vestibular migraine

Background

Vestibular migraine (VM), an intricate subtype of migraine, amalgamates the dual attributes of migraine and vestibular disorders. In clinical settings, individuals with VM frequently articulate concerns regarding the manifestation of subjective cognitive impairment. This cognitive dysfunction is intricately linked with diminished mobility, heightened susceptibility to falls, and increased absenteeism in afflicted patients. Consequently, comprehending the features of cognitive impairment in VM patients holds potential clinical significance. The pursuit of rapid and objective methods for detection and assessment is foundational and prerequisite for efficacious cognitive management of VM patients.

Methods

The study encompassed 50 patients diagnosed with vestibular migraine and recruited 50 age-sex matched healthy controls. All participants underwent anti-saccade tasks, and cognitive evaluation was performed using the MMSE and MoCA to assess overall cognitive function. Additionally, RBANS scales were employed to measure specific cognitive domains.

Results

The VM patients and normal controls demonstrated statistical parity in terms of age, gender, education, weight, and BMI, with no significant differences observed. Analysis of cognitive scores divulged a marked increase in the incidence of Mild Cognitive Impairment (MCI) in VM patients compared to Healthy Controls (HCs). Both MMSE and MoCA scores were notably lower in VM patients compared to their healthy counterparts. The RBANS cognitive test indicated significant impairment in immediate memory, visuospatial construction, language, attention, and delayed memory among VM patients. Notably, the Trail Making Test and Stroop Color-Word Test revealed compromised processing speed and executive function cognitive domains. The anti-saccadic task highlighted significantly elevated anti-saccadic latency and frequency of direction errors in vestibular migraine patients. Symptom severity, illness duration, and episode frequency in VM patients positively correlated with counter-scanning errors and negatively correlated with cognitive performance across diverse cognitive domains.

Conclusion

VM patients exhibit cognitive decline across multiple cognitive domains during the interictal period. This cognitive impairment may not be fully reversible, underscoring its potential clinical significance for cognitive management in VM patients. The sensitivity of anti-saccade tasks to the cognitive status of VM patients positions them as promising objective indicators for diagnosis, intervention, and evaluation of cognitive impairment effects in VM in future applications.

Impacts of education level on Montreal Cognitive Assessment and saccades in community residents from Western China

OBJECTIVES

This cross-sectional study sought to evaluate the effectiveness of the Montreal Cognitive Assessment (MoCA) and saccade in discerning the cognitive function levels among community populations characterized by diverse educational backgrounds.

METHODS

Data from 665 Western China individuals encompassed MoCA scores and saccade performance. The study examined how education level and age influenced these assessments and highlighted the contrasting abilities of these measures in detecting cognitive abnormalities.

RESULTS

The saccade model revealed a consistent cognitive impairment prevalence (15.5%) compared to previous clinical data (9.7% to 23.3%), while MoCA exhibited variable rates (25.1% to 52.8%). Notably, saccades and MoCA significantly diverged in detecting cognitive dysfunction. Additionally, education level had a greater impact on MoCA (effect size: 0.272) compared to saccades (0.024) affecting all MoCA sub-items, with age exerting a smaller influence on MoCA (0.037) compared to saccades (0.056).

CONCLUSION

Saccades are less susceptible to the influence of education level when compared to MoCA, making saccade a potentially more suitable cognitive screening tool for rural community populations.

SIGNIFICANCE

This study represents a pioneering approach by employing saccade detection within community populations to distinguish cognitive function status.

Application and progress of advanced eye movement examinations in cognitive impairment

The worldwide incidence of cognitive impairment is escalating, yet no effective solutions for these afflictions have been discovered. Consequently, the importance of early identification and immediate intervention is heightened. Advanced eye movements-a form of voluntary eye movements that includes anti-saccades, memory-guided saccades, predictive saccades, pro-saccades and gap/overlap saccades, mediated by the cerebral cortex and subcortical pathways reflect cognitive levels and functions across different domains. In view of their objectivity, reproducibility, and non-invasive characteristics, advanced eye movement examination possesses significant prospective utility across a wide range of cognitive impairment. This paper extensively reviews various models associated with advanced eye movement examinations and their current applications in cognitive impairment such as Alzheimer's disease, Lewy body dementia and frontotemporal dementia. Advanced eye movement examination can serve as a biomarker for early screening diagnosis and research on cognitive impairment. In the future, combining advanced eye movement examination with neuropsychological scale assessment and other diagnostic methods may contribute to further early identification of these types of diseases.

GABA in the anterior cingulate cortex mediates the association of white matter hyperintensities with executive function: a magnetic resonance spectroscopy study

White matter hyperintensities (WMH) and gamma-aminobutyric acid (GABA) are associated with executive function. Multiple studies suggested cortical alterations mediate WMH-related cognitive decline. The aim of this study was to investigate the crucial role of cortical GABA in the WMH patients. In the 87 WMH patients (46 mild and 41 moderate to severe) examined in this study, GABA levels in the anterior cingulate cortex (ACC) and posterior cingulate cortex (PCC) assessed by the Meshcher-Garwood point resolved spectroscopy (MEGA-PRESS) sequence, WMH volume and executive function were compared between the two groups. Partial correlation and mediation analyses were carried out to examine the GABA levels in mediating the association between WMH volume and executive function. Patients with moderate to severe WMH had lower GABA+/Cr in the ACC (p = 0.034) and worse executive function (p = 0.004) than mild WMH patients. In all WMH cases, the GABA+/Cr levels in the ACC mediated the negative correlation between WMH and executive function (ab: effect = -0.020, BootSE = 0.010, 95% CI: -0.042 to -0.004). This finding suggested GABA+/Cr levels in the ACC might serve as a protective factor or potential target for preventing the occurrence and progression of executive function decline in WMH people.

Executive function measures of participants with mild cognitive impairment: Systematic review and meta-analysis of event-related potential studies

OBJECTIVE

Objective measurements of executive functions using event-related potential (ERP) may be used as markers for differentiating healthy controls (HC) from patients with mild cognitive impairment (MCI). ERP is non-invasive, cost-effective, and affordable. Older adults with MCI demonstrate deteriorated executive function, serving as a potentially valid neurophysiological marker for identifying MCI. We aimed to review published ERP studies on executive function in older adults with MCI and summarize the performance differences by component between healthy older adults and older adults with MCI.

METHODS

Eight electronic databases (Web of Science, PubMed, ScienceDirect, American Psychological Association PsycNet, Cochrane Library, Scopus, Embase, and Ovid) were searched for the study. Articles published from January 1 to December 31, 2022, were considered for this review. A random-effects meta-analysis and between-study heterogeneity analysis were conducted using Comprehensive Meta-Analysis V3.0 software.

RESULTS

We identified 7829 articles of which 28 met the full inclusion criteria and were included in the systematic review and analyses. Our pooled analysis suggested that participants with MCI can be differentiated from HC by significant P200, P300, and N200 latencies. The P100 and P300 amplitudes were significantly smaller in participants with MCI when compared with those in the HCs, and the patients with MCI showed increased N200 amplitudes. Our findings provide new insights into potential electrophysiological biomarkers for diagnosing MCI.

Research Progress of Eye Movement Analyses and its Detection Algorithms in Alzheimer's Disease

Alzheimer's disease (AD) has been considered one of the most challenging forms of dementia. The earlier the people are diagnosed with AD, the easier it is for doctors to find a treatment. Based on the previous literature summarizing the research results on the relationship between eye movement and AD before 2013, this paper reviewed 34 original eye movements research papers only closely related to AD published in the past ten years and pointed out that the prosaccade (4 papers) and antisaccade (5 papers) tasks, reading tasks (3 papers), visual search tasks (3 papers) are still the research objects of many researchers, Some researchers have looked at King-Devick tasks (2 papers), reading tasks (3 papers) and special tasks (8 papers), and began to use combinations of different saccade tasks to detect the relationship between eye movement and AD, which had not been done before. These reflect the diversity of eye movement tasks and the complexity and difficulty of the relationship between eye movement and AD. On this basis, the current processing and analysis methods of eye movement datasets are analyzed and discussed in detail, and we note that certain key data that may be especially important for the early diagnosis of AD by using eye movement studies cannot be miss-classified as noise and removed. Finally, we note that the development of methods that can accurately denoise and classify and quickly process massive eye movement data is quite significant for detecting eye movements in early diagnosis of AD.

The application of saccades to assess cognitive impairment among older adults: a systematic review and meta-analysis

BACKGROUND

Saccade is a novel and feasible method for cognition assessment and has potential to screen older people with cognitive impairment.

OBJECTIVES

To systematically summarize the evidence and determine whether different saccade parameters can effectively identify patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD).

METHODS

English and Chinese databases were searched until 19 April 2022. Studies analyzing saccade parameters in older adults with normal cognition, MCI, or AD were included. Two researchers independently performed the screening, data extraction, and quality appraisal. Meta-analyses were conducted and standard mean differences and 95% confidence intervals were estimated with a random effects model.

RESULTS

Thirty-five studies were included, and 26 studies were pooled for the meta-analysis. The results demonstrated that patients with cognitive impairment exhibited longer latency and lower accuracy rates in the prosaccade and antisaccade tasks, along with lower corrected error rates in the antisaccade tasks. However, the pooled results for antisaccades were more stable, providing the ability to distinguish patients with cognitive impairment among older adults. The results of the subgroup analyses revealed that only the accuracy rates of the antisaccades differed significantly between people with MCI and AD. Regarding the differences between older adults with normal cognition and those with MCI, the effect sizes of latency and the accuracy rates of saccades as well as the corrected error rates of antisaccades were significant.

CONCLUSIONS

Saccades, especially antisaccades, are a potential screening and assessment tool for distinguishing older adults with MCI or AD from those with normal cognition.

Potential Ocular Biomarkers for Early Detection of Alzheimer's Disease and Their Roles in Artificial Intelligence Studies

Alzheimer's disease (AD) is the leading cause of dementia worldwide. Early detection is believed to be essential to disease management because it enables physicians to initiate treatment in patients with early-stage AD (early AD), with the possibility of stopping the disease or slowing disease progression, preserving function and ultimately reducing disease burden. The purpose of this study was to review prior research on the use of eye biomarkers and artificial intelligence (AI) for detecting AD and early AD. The PubMed database was searched to identify studies for review. Ocular biomarkers in AD research and AI research on AD were reviewed and summarized. According to numerous studies, there is a high likelihood that ocular biomarkers can be used to detect early AD: tears, corneal nerves, retina, visual function and, in particular, eye movement tracking have been identified as ocular biomarkers with the potential to detect early AD. However, there is currently no ocular biomarker that can be used to definitely detect early AD. A few studies that used AI with ocular biomarkers to detect AD reported promising results, demonstrating that using AI with ocular biomarkers through multimodal imaging could improve the accuracy of identifying AD patients. This strategy may become a screening tool for detecting early AD in older patients prior to the onset of AD symptoms.

Understanding mental fatigue and its detection: a comparative analysis of assessments and tools

Mental fatigue has shown to be one of the root causes of decreased productivity and overall cognitive performance, by decreasing an individual's ability to inhibit responses, process information and concentrate. The effects of mental fatigue have led to occupational errors and motorway accidents. Early detection of mental fatigue can prevent the escalation of symptoms that may lead to chronic fatigue syndrome and other disorders. To date, in clinical settings, the assessment of mental fatigue and stress is done through self-reported questionnaires. The validity of these questionnaires is questionable, as they are highly subjective measurement tools and are not immune to response biases. This review examines the wider presence of mental fatigue in the general population and critically compares its various detection techniques (i.e., self-reporting questionnaires, heart rate variability, salivary cortisol levels, electroencephalogram, and saccadic eye movements). The ability of these detection tools to assess inhibition responses (which are sensitive enough to be manifested in a fatigue state) is specifically evaluated for a reliable marker in identifying mentally fatigued individuals. In laboratory settings, antisaccade tasks have been long used to assess inhibitory control and this technique can potentially serve as the most promising assessment tool to objectively detect mental fatigue. However, more studies need to be conducted in the future to validate and correlate this assessment with other existing measures of mental fatigue detection. This review is intended for, but not limited to, mental health professionals, digital health scientists, vision researchers, and behavioral scientists.

Correlating Eye-Tracking Fixation Metrics and Neuropsychological Assessment after Ischemic Stroke

Background and Objectives: Stroke survivors commonly experience cognitive deficits, which significantly impact their quality of life. Integrating modern technologies like eye tracking into cognitive assessments can provide objective and non-intrusive measurements. Materials and Methods: This study aimed to evaluate the cognitive and visual processing capabilities of stroke patients using eye-tracking metrics and psychological evaluations. A cohort of 84 ischemic stroke patients from the N-PEP-12 clinical study was selected for secondary analysis, based on the availability of eye-tracking data collected during a visual search task using an adapted Trail Making Test. Standardized cognitive assessments, including the Montreal Cognitive Assessment (MoCA) and digit span tasks, were also conducted. Results: Correlation analyses revealed some notable relationships between eye-tracking metrics and cognitive measures, such as a positive correlation between Symbol Search performance and the number of fixations. Anxiety levels were found to be positively correlated with first fixation duration, while longer first fixation durations were associated with poorer cognitive performance. However, most correlations were not statistically significant. Nonparametric ANOVA showed no significant differences in fixation metrics across the visits. Conclusions: These findings suggest a complex relationship between cognitive status, gaze fixation behavior, and psychological well-being in stroke patients. Further research with larger sample sizes and analysis of saccadic eye movements is needed to better understand these relationships and inform effective interventions for stroke rehabilitation.

Eye-tracking paradigms for the assessment of mild cognitive impairment: a systematic review

Mild cognitive impairment (MCI), representing the 'transitional zone' between normal cognition and dementia, has become a novel topic in clinical research. Although early detection is crucial, it remains logistically challenging at the same time. While traditional pen-and-paper tests require in-depth training to ensure standardized administration and accurate interpretation of findings, significant technological advancements are leading to the development of procedures for the early detection of Alzheimer's disease (AD) and facilitating the diagnostic process. Some of the diagnostic protocols, however, show significant limitations that hamper their widespread adoption. Concerns about the social and economic implications of the increasing incidence of AD underline the need for reliable, non-invasive, cost-effective, and timely cognitive scoring methodologies. For instance, modern clinical studies report significant oculomotor impairments among patients with MCI, who perform poorly in visual paired-comparison tasks by ascribing less attentional resources to novel stimuli. To accelerate the Global Action Plan on the Public Health Response to Dementia 2017-2025, this work provides an overview of research on saccadic and exploratory eye-movement deficits among older adults with MCI. The review protocol was drafted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Electronic databases were systematically searched to identify peer-reviewed articles published between 2017 and 2022 that examined visual processing in older adults with MCI and reported gaze parameters as potential biomarkers. Moreover, following the contemporary trend for remote healthcare technologies, we reviewed studies that implemented non-commercial eye-tracking instrumentation in order to detect information processing impairments among the MCI population. Based on the gathered literature, eye-tracking-based paradigms may ameliorate the screening limitations of traditional cognitive assessments and contribute to early AD detection. However, in order to translate the findings pertaining to abnormal gaze behavior into clinical applications, it is imperative to conduct longitudinal investigations in both laboratory-based and ecologically valid settings.

Transferability and sustainability of process-based multi-task adaptive cognitive training in community-dwelling older adults with mild cognitive impairment: a randomized controlled trial

BACKGROUND

Cognitive training shows promising effects for improving cognitive domains in individuals with mild cognitive impairment (MCI), including the crucial predictive factor of executive function (EF) for dementia prognosis. Few studies have paid sufficient emphasis on the training-induced effects of cognitive training programs, particularly with regards to targeting EF. A process-based multi-task adaptive cognitive training (P-bM-tACT) program targeting EF is required to examine direct, transfer, and sustainability effects in older adults with MCI.

OBJECTIVE

This study aimed to evaluate the direct effects of a P-bM-tACT program on EF, the transfer effects on untrained cognitive domains, and further explore the sustainability of training gains for older adults with MCI in the community.

METHODS

In a single-blind, randomized controlled trial, 92 participants with MCI were randomly assigned to either the intervention group, participating in a P-bM-tACT program (3 training sessions/week, 60 min/session for 10 weeks) or the wait-list control group, accepting a health education program on MCI (1 education session/ twice a week, 40-60 min/session for 10 weeks). The direct and transfer effects of the P-bM-tACT program were assessed at baseline, immediately after 10 weeks of training, and the 3-month follow-up. Repeated measures analysis of variance and a simple effect test were used to compare the direct and transfer effects over the 3-time points between the two groups.

RESULTS

The P-bM-tACT program yielded a greater benefit of direct and transfer effects in the intervention group participants than in the wait-list control group. Combined with the results of simple effect tests, the direct and transfer effects of participants in the intervention group significantly increased immediately after 10 weeks of training compared to the baseline (F = 14.702 ~ 62.905, p < 0.05), and these effects were maintained at the 3-month follow-up (F = 19.595 ~ 122.22, p < 0.05). Besides, the acceptability of the cognitive training program was established with a high adherence rate of 83.4%.

CONCLUSIONS

The P-bM-tACT program exerted positive direct and transfer effects on the improvement of cognitive function, and these effects were sustained for 3 months. The findings provided a viable and potential approach to improving cognitive function in older adults with MCI in the community.

TRIAL REGISTRATION

The trial was registered at Chinese Clinical Trials Registry on 09/01/2019 ( www.chictr.org.cn ; Number Registry: ChiCTR1900020585).

Eyes on dementia: an overview of the interplay between eye movements and cognitive decline

The economic and disease burden of dementia is forecasted to continue increasing. Considering its cognitive effects, timely diagnosis is important in developing a stage-based treatment plan and gathering data to support advocacy efforts and plan healthcare and social services. Eye-tracking technology has emerged as an efficient diagnostic tool in clinical practice and experimental studies. This review aimed to comprehensively analyze various aspects of eye-tracking technology, including pupillometry parameters, eye movements, eye-tracking devices, and neuropsychological tools. We conducted a systematic review retrieving articles published in the last ten years from six databases. Our results provide a complex overview for each included form of dementia/cognitive decline in terms of patient characteristics (age, sex-disaggregated by included pathologies), inclusion and exclusion criteria, devices, and neuropsychological tools. We also summarized findings on fixation stability tasks, saccadic evaluation, pupillometry, scene perception, object recognition, spatial memory, eye-tracking video tasks, and visual search. The eye-tracking method has become more common in cognitive assessments.

Saccadic Eye Movements in Patients with Mild Cognitive Impairment: A Longitudinal Study

Saccadic eye movements are one of the sensitive and noninvasive methods to help monitor the cognitive course of mild cognitive impairment (MCI). The study aimed to evaluate both pro and anti-saccade longitudinally and the relationship between cognitive functions and eye movements in MCI subgroups and healthy controls (HCs) at a two-year follow-up. This study revealed that the anti-saccade anticipatory responses decreased in amnestic MCI (aMCI). Correct vertical pro-saccades increased in non-amnestic MCI (naMCI), while the express saccades decreased. Our study demonstrated that longer than two years of follow-up is necessary to monitor the course of MCI. Findings of the relationships between longitudinal changes of saccades and cognitive measurements demonstrated the usability of eye movements in evaluating the process of MCI.

Attentional Control in Subjective Cognitive Decline

BACKGROUND

Attention is an essential cognitive ability that is necessary in other cognitive processes. Only few studies have focused on decline in specific functions of attention in older adults with cognitive decline. No research explores the difference in the proactive and reactive mode of control between the healthy control (HC) and older adults with subjective cognitive decline (SCD).

OBJECTIVE

The current work investigated whether there was any decline in alerting, orienting, and executive control in SCD. Particularly, the present study further explored the impairment of the proactive and reactive control in SCD.

METHODS

We recruited 25 HC and 26 SCD. All participants first finished a set of neuropsychological assessments. They then completed an Attention Network Test for measuring the alerting, orienting, and executive control, the List-wide and the Item-specific Proportion Congruency Effect task for measuring the proactive and reactive mode of control, respectively.

RESULTS

No difference was found in alerting, orienting, and executive control measured by the ANT between SCD and HC. The results also indicated no difference in the reactive control between SCD and HC. However, older adults with SCD performed worse in the proactive control as compared to HC.

CONCLUSION

Older adults with SCD showed an impairment in the proactive control. The current findings help us better understand objective decline in cognitive domains other than memory and shed light on early assessment and prevention of AD.

Antisaccadic eye movements in middle-aged individuals with a family history of Alzheimer's disease

Background

Antisaccade is closely associated with cognitive ability in Alzheimer's disease (AD). However, studies regarding antisaccade in the early stages of AD are scarce. Considering that first-degree family history is a well-established risk factor for AD, we explored the influence of family history on the performance of antisaccade tasks in individuals with normal cognition.

Methods

In total, 44 participants (aged 50-66 years) with a family history of AD (FH+) and 44 age-, gender-, and educational level-matched controls (FH-) were enrolled in our study. After cognitive assessment using the Montreal Cognitive Assessment and Mini-mental State Examination, participants underwent antisaccade trials, and all parameters were recorded using an eye tracker.

Results

While the average velocity was relatively lower in FH+ individuals than in FH- individuals (107.9 ± 14.3°/s vs. 132.9 ± 23.7°/s, p < 0.001), FH+ individuals surprisingly showed relatively fewer uninhibited reflexive saccades (44.7 ± 26.0% vs. 56.2 ± 24.7%, p = 0.037) than the control group. They also required a relatively shorter time to detect and correct false saccades (121.6 ± 40.7 ms vs. 143.9 ± 37.0 ms, p = 0.023).

Conclusions

This study showed that family history is associated with alterations in antisaccadic parameters, suggesting that eye tracking can be used to assess oculomotor control and executive function in individuals at risk of developing dementia.

Paraquat induces microglial cause early neuronal synaptic deficits through activation of the classical complement cascade response

Synapse loss is considered to be an early event in the dysfunction of the central nervous system (CNS), precedes neuronal decline, which is the main pathological change in mild cognitive impairment (MCI). Accumulating evidence has shown that neuronal synapse loss is associated with hyperactivity of microglial phagocytosis. In the CNS, microglia act as macrophages to clear cellular debris and weakened synapses, but the mechanism by which microglia activation leads to phagocytosis disorder remains unclear. Therefore, we treated mice with paraquat (PQ) in intraperitoneal injection to explore the mechanism by which microglia exert immunotoxicity in the CNS and cause neuronal synapse loss. Immunofluorescence results exposed synapses decreased with PQ exposure time, but the staining HE and Nissl showed that neuronal cell bodies were hardly affected. Fluorescence co-localization found that C1q (classical complement cascade initiation factor) was gradually deposited in the postsynaptic membrane of neurons to trigger the cascade reaction, thereby causing the excessive deposition of C3, a key factor of the classical complement cascade, and further induces hyperactivation of microglia, leads to phagocytosis disorder. IHC results demonstrated that the parallel relationship. Therefore, all our preliminary results throw light on the mechanism by which PQ abnormally triggers the immune system to produce immunotoxicity leading to microglial phagocytic dysfunction.

Eye-tracking training improves the learning and memory of children with learning difficulty

Children who experience difficulty in learning at mainstream schools usually are provided with remediation classes after school to facilitate their learning. The present study aims to evaluate an innovative eye-tracking training as possible alternative remediation. Our previous findings showed that children who received eye-tracking training demonstrated improved attention and inhibitory control, and the present randomized controlled study aims to evaluate if eye-tracking training can also enhance the learning and memory of children. Fifty-three primary school students with learning difficulty (including autism spectrum disorder, attention-deficit/hyperactivity disorder, specific learning disorder, specific language impairment and borderline intellectual functioning) were recruited and randomly assigned to either the Eye-tracking Training group or the after-school remediation class. They were assessed on their learning and memory using the Hong Kong List Learning Test before and after 8-month training. Twenty weekly parallel sessions of training, 50 min per session, were provided to each group. Children who received the eye-tracking training, not those in the control group, showed a significant improvement in memory as measured by the delayed recall. In addition, the Eye-Tracking Training group showed significantly faster learning than the control group. Also, the two groups showed a significant improvement in their reading abilities. In sum, eye-tracking training may be effective training for enhancing the learning and memory of children with learning difficulties.

Multiple step saccades in simply reactive saccades could serve as a complementary biomarker for the early diagnosis of Parkinson’s disease

Objective

It has been argued that the incidence of multiple step saccades (MSS) in voluntary saccades could serve as a complementary biomarker for diagnosing Parkinson’s disease (PD). However, voluntary saccadic tasks are usually difficult for elderly subjects to complete. Therefore, task difficulties restrict the application of MSS measurements for the diagnosis of PD. The primary objective of the present study is to assess whether the incidence of MSS in simply reactive saccades could serve as a complementary biomarker for the early diagnosis of PD.

Materials and methods

There were four groups of human subjects: PD patients, mild cognitive impairment (MCI) patients, elderly healthy controls (EHCs), and young healthy controls (YHCs). There were four monkeys with subclinical hemi-PD induced by injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) through the unilateral internal carotid artery and three healthy control monkeys. The behavioral task was a visually guided reactive saccade.

Results

In a human study, the incidence of MSS was significantly higher in PD than in YHC, EHC, and MCI groups. In addition, receiver operating characteristic (ROC) analysis could discriminate PD from the EHC and MCI groups, with areas under the ROC curve (AUCs) of 0.76 and 0.69, respectively. In a monkey study, while typical PD symptoms were absent, subclinical hemi-PD monkeys showed a significantly higher incidence of MSS than control monkeys when the dose of MPTP was greater than 0.4 mg/kg.

Conclusion

The incidence of MSS in simply reactive saccades could be a complementary biomarker for the early diagnosis of PD.

Associations of executive function and age of first use of methamphetamine with methamphetamine relapse

BACKGROUND AND AIMS

Methamphetamine (MA) is a psychostimulant associated with a high relapse rate among patients with MA use disorder (MUD). Long-term use of MA is associated with mental disorders, executive dysfunction, aggressive behaviors, and impulsivity among patients with MUD. However, identifying which factors may be more closely associated with relapse has not been investigated. Thus, we aimed to investigate the psychological factors and the history of MA use that may influence MA relapse.

METHODS

This cross-sectional study included 168 male MUD patients (MUD group) and 65 healthy male residents (control group). Each patient was evaluated with self-report measures of executive dysfunction, psychopathological symptoms, impulsiveness, aggressiveness, and history of MA use. Data were analyzed with t-tests, analyses of variance, and correlation and regression analyses.

RESULTS

The MUD group reported greater executive dysfunction, psychopathological symptoms, impulsivity, and aggression than the control group. Lower age of first MA use was associated both with having relapsed one or more times and with having relapsed two or more times; greater executive dysfunction was associated only with having relapsed two or more times.

CONCLUSION

Patients with MUD reported worse executive function and mental health. Current results also suggest that lower age of first MA use may influence relapse rate in general, while executive dysfunction may influence repeated relapse in particular. The present results add to the literature concerning factors that may increase the risk of relapse in individuals with MUD.

Executive-function tasks in patients with mild cognitive impairment and Alzheimer's Disease: Effects of decline and gender

It is exceedingly rare to find studies that analyze the effect of gender differences in executive-function tasks in normal cognitive aging, Mild Cognitive Impairment (MCI) and Alzheimer's Disease (AD). The objective of the present study was to analyze the mean differences in performance in four executive-function tasks, the Clock Drawing Test verbal-command, Clock Drawing Test-copy, Phonetic Fluency Test and Trail Making Test-A, according to the gender and impairment group variables. A total of 90 participants (30 patients with Alzheimer's Disease, 30 patients with Mild Cognitive Impairment, and 30 healthy elderly participants; 50% men and 50% women in each group) took part in the study. As expected, the results showed a main effect of the group in most tasks, with a progressively worse performance according to cognitive impairment. Regarding the effect of gender, there were no significant differences in the Mild Cognitive Impairment and healthy elderly groups, but a significantly higher performance of women compared to men was found in the Alzheimer's group. The clinical and theoretical implications of these results are discussed. In particular, the abnormal performance of women with Alzheimer's in the sample may be related to a possible cognitive reserve due to social and educational background in their sociocultural and generational context.

The effectiveness of eye tracking in the diagnosis of cognitive disorders: A systematic review and meta-analysis

BACKGROUND

Eye tracking (ET) is a viable marker for the recognition of cognitive disorders. We assessed the accuracy and clinical value of ET for the diagnosis of cognitive disorders in patients.

METHODS

We searched the Medline, Embase, Web of Science, Cochrane Library, and Pubmed databases from inception to March 2, 2021, as well as the reference lists of identified primary studies. We included articles written in English that investigated ET for cognitive disorder patients-Mild cognitive impairment (MCI), Alzheimer's disease (AD), Amyotrophic lateral sclerosis (ALS), and dementia. Two independent researchers extracted the data and the characteristics of each study; We calculated pooled sensitivities and specificities. A hierarchical summary of receiver performance characteristics (HSROC) model was used to test the diagnostic accuracy of ET for cognitive impairment (CI).

FINDINGS

11 studies met the inclusion criteria and were included in qualitative comprehensive analysis. Meta-analysis was performed on 9 trials using Neuropsychological Cognitive Testing (NCT) as the reference standard. The comprehensive sensitivity and specificity of ET for detecting cognitive disorders were 0.75 (95% CI 0.72-0.79) and 0.73 (95% CI 0.70 to 0.76), respectively. The combined positive likelihood ratio (LR+) was 2.74 (95%CI 2.32-3.24) and the negative likelihood ratio (LR-) was 0.27 (95%CI 0.18-0.42).

CONCLUSIONS

This review showed that ET technology could be used to detect the decline in CI, clinical use of ET techniques in combination with other tools to assess CI can be encouraged.