Publications by authors named "Görsev Yener"

83 Publications

A Virtual Reality-Based Screening Test for Cognitive Impairment in Small Vessel Disease.

J Alzheimers Dis Rep 2021 Mar 8;5(1):161-169. Epub 2021 Mar 8.

Department of Neurology, School of Medicine, Dokuz Eylul University, Izmir, Turkey.

Background: There is a need for new practical tools to assess the cognitive impairment of small vessel disease (SVD) patients in the clinic.

Objective: This study aimed to examine cognitive functioning by administering the Virtual Supermarket (VST) in patients with SVD with cognitive impairment (SVD-CI, N = 32), cognitively normal SVD (SVD-CN, N = 37), and age-and education-matched healthy controls (HC, N = 30).

Methods: The tablet-based VST application and comprehensive traditional pencil-and-paper neuropsychological tests assessing memory, attention, executive function, visuospatial function, and language were administered to all participants.

Results: A moderate correlation was found between the "Duration" and "Correct Quantities" variables of VST and visuospatial function and general cognitive status composite Z scores across SVD-CI patients. "Duration" and "Correct Money" variables were moderately related to memory, executive functions, and visuospatial function composite Z scores across SVD-CN patients. A combination of all VST variables discriminated SVD-CI and HC with a correct classification rate of 81%, a sensitivity of 78%, and a specificity of 84%.

Conclusion: This study is the first to evaluate cognitive functions employing the VST in SVD with and without cognitive impairment. It provides encouraging preliminary findings of the utility of the VST as a screening tool in the assessment of cognitive impairment and the differentiation of SVD patients from HC. In the future, validation studies of the VST with larger samples are needed.
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http://dx.doi.org/10.3233/ADR-200257DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8075552PMC
March 2021

Complexity of EEG Dynamics for Early Diagnosis of Alzheimer's Disease Using Permutation Entropy Neuromarker.

Comput Methods Programs Biomed 2021 Apr 16;206:106116. Epub 2021 Apr 16.

Department of Electrical and Electronics Engineering, Dicle University, Diyarbakir, Turkey.

Background And Objective: Electroencephalogram (EEG) is one of the most demanded screening tools that investigates the effects of Alzheimer's Disease (AD) on human brain. Identification of AD in early stage gives rise to efficient treatment in dementia. Mild Cognitive Impairment (MCI) is considered as a conversion stage. Reducing EEG complexity can be used as a marker to detect AD. The aim of this study is to develop a 3-way diagnostic classification using EEG complexity in the detection of MCI/AD in clinical practice. This study also investigates the effects of different eyes states, i.e. eyes-open, eyes-closed on classification performance.

Methods: EEG recordings from 85 AD, 85 MCI subjects, and 85 Healthy Controls with eyes-open and eyes- closed are analyzed. Permutation Entropy (PE) values are computed from frontal, central, parietal, temporal, and occipital regions for each EEG epoch. Distribution of PE values are visualized to observe discrimination of MCI/AD with HC. Visual investigations are combined with statistical analysis using ANOVA to determine whether groups are significant or not. Multinomial Logistic Regression model is applied to feature sets in order to classify participants individually.

Results: Distribution of measured PE shows that EEG complexity is lower in AD and higher in HC group. MCI group is observed as an intermediate form due to heterogeneous values. Results from 3-way classification indicate that F1-scores and rates of sensitivity and specificity achieve the highest overall discrimination rates reaching up to 100% for at TP8 for eyes-closed condition; and C3, C4, T8, O2 electrodes for eyes-open condition. Classification of HC from both patient groups is achieved best. Eyes-open state increases discrimination of MCI and AD.

Conclusions: This nonlinear EEG methodology study contributes to literature with high discrimination rates for identification of AD. PE is recommended as a practical diagnostic neuro-marker for AD studies. Resting state EEG at eyes-open condition can be more advantageous over eyes-closed EEG recordings for diagnosis of AD.
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http://dx.doi.org/10.1016/j.cmpb.2021.106116DOI Listing
April 2021

Proteome profiling of neuron-derived exosomes in Alzheimer's disease reveals hemoglobin as a potential biomarker.

Neurosci Lett 2021 Apr 24;755:135914. Epub 2021 Apr 24.

Izmir Biomedicine and Genome Center, Izmir, Turkey; Izmir International Biomedicine and Genome Institute, Dokuz Eylul University, Izmir, Turkey; Department of Neuroscience, Health Science Institute, Dokuz Eylul University, Izmir, Turkey. Electronic address:

Alzheimer's disease is a chronic and progressive neurodegenerative disorder, which is the most common cause of dementia worldwide. Although amyloid plaques and neurofibrillary tangles are identified as the hallmarks of the disease, the only valid diagnostic method yet is post-mortem imaging of these molecules in brain sections. Exosome is a type of extracellular vesicles secreted into extracellular space and plays fundamental roles in healthy and pathological conditions, including cell-to-cell communication. In this study, we aimed to investigate the proteomic contents of neuron-derived exosomes (NDEs) from AD patients and healthy controls (HCs) to identify a possible marker for AD diagnosis. We identified alpha-globin, beta-globin, and delta-globin increase in neuron-derived exosomes of AD patients compared to HCs with LC-MS/MS proteomics analysis. Then, we confirmed the high hemoglobin (Hb) level in NDEs of AD patients with ELISA. We found the area under the curve of hemoglobin level as 0.6913 with ROC analysis. Cargo proteins of NDEs may be useful diagnostic biomarker for AD.
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http://dx.doi.org/10.1016/j.neulet.2021.135914DOI Listing
April 2021

Measures of resting state EEG rhythms for clinical trials in Alzheimer's disease: Recommendations of an expert panel.

Alzheimers Dement 2021 Apr 15. Epub 2021 Apr 15.

School of Psychology, University of Glasgow, Glasgow, UK.

The Electrophysiology Professional Interest Area (EPIA) and Global Brain Consortium endorsed recommendations on candidate electroencephalography (EEG) measures for Alzheimer's disease (AD) clinical trials. The Panel reviewed the field literature. As most consistent findings, AD patients with mild cognitive impairment and dementia showed abnormalities in peak frequency, power, and "interrelatedness" at posterior alpha (8-12 Hz) and widespread delta (< 4 Hz) and theta (4-8 Hz) rhythms in relation to disease progression and interventions. The following consensus statements were subscribed: (1) Standardization of instructions to patients, resting state EEG (rsEEG) recording methods, and selection of artifact-free rsEEG periods are needed; (2) power density and "interrelatedness" rsEEG measures (e.g., directed transfer function, phase lag index, linear lagged connectivity, etc.) at delta, theta, and alpha frequency bands may be use for stratification of AD patients and monitoring of disease progression and intervention; and (3) international multisectoral initiatives are mandatory for regulatory purposes.
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http://dx.doi.org/10.1002/alz.12311DOI Listing
April 2021

EEG measures for clinical research in major vascular cognitive impairment: recommendations by an expert panel.

Neurobiol Aging 2021 Mar 10;103:78-97. Epub 2021 Mar 10.

Centre for Healthy Brain Ageing (CHeBA), School of Psychiatry, University of New South Wales; Neuropsychiatric Institute, The Prince of Wales Hospital, Sydney, Australia.

Vascular contribution to cognitive impairment (VCI) and dementia is related to etiologies that may affect the neurophysiological mechanisms regulating brain arousal and generating electroencephalographic (EEG) activity. A multidisciplinary expert panel reviewed the clinical literature and reached consensus about the EEG measures consistently found as abnormal in VCI patients with dementia. As compared to cognitively unimpaired individuals, those VCI patients showed (1) smaller amplitude of resting state alpha (8-12 Hz) rhythms dominant in posterior regions; (2) widespread increases in amplitude of delta (< 4 Hz) and theta (4-8 Hz) rhythms; and (3) delayed N200/P300 peak latencies in averaged event-related potentials, especially during the detection of auditory rare target stimuli requiring participants' responses in "oddball" paradigms. The expert panel formulated the following recommendations: (1) the above EEG measures are not specific for VCI and should not be used for its diagnosis; (2) they may be considered as "neural synchronization" biomarkers to enlighten the relationships between features of the VCI-related cerebrovascular lesions and abnormalities in neurophysiological brain mechanisms; and (3) they may be tested in future clinical trials as prognostic biomarkers and endpoints of interventions aimed at normalizing background brain excitability and vigilance in wakefulness.
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http://dx.doi.org/10.1016/j.neurobiolaging.2021.03.003DOI Listing
March 2021

A Fast Transform for Brain Connectivity Difference Evaluation.

Neuroinformatics 2021 Apr 12. Epub 2021 Apr 12.

Fondazione Istituto Italiano di Tecnologia, Ferrara, Italy.

Anatomical and dynamical connectivity are essential to healthy brain function. However, quantifying variations in connectivity across conditions or between patient populations and appraising their functional significance are highly non-trivial tasks. Here we show that link ranking differences induce specific geometries in a convenient auxiliary space that are often easily recognisable at mere eye inspection. Link ranking can also provide fast and reliable criteria for network reconstruction parameters for which no theoretical guideline has been proposed.
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http://dx.doi.org/10.1007/s12021-021-09518-7DOI Listing
April 2021

Abnormalities of Cortical Sources of Resting State Alpha Electroencephalographic Rhythms are Related to Education Attainment in Cognitively Unimpaired Seniors and Patients with Alzheimer's Disease and Amnesic Mild Cognitive Impairment.

Cereb Cortex 2021 Mar;31(4):2220-2237

Department of Physiology and Pharmacology "Vittorio Erspamer", Sapienza University of Rome, Rome, Italy.

In normal old (Nold) and Alzheimer's disease (AD) persons, a high cognitive reserve (CR) makes them more resistant and resilient to brain neuropathology and neurodegeneration. Here, we tested whether these effects may affect neurophysiological oscillatory mechanisms generating dominant resting state electroencephalographic (rsEEG) alpha rhythms in Nold and patients with mild cognitive impairment (MCI) due to AD (ADMCI). Data in 60 Nold and 70 ADMCI participants, stratified in higher (Edu+) and lower (Edu-) educational attainment subgroups, were available in an Italian-Turkish archive. The subgroups were matched for age, gender, and education. RsEEG cortical sources were estimated by eLORETA freeware. As compared to the Nold-Edu- subgroup, the Nold-Edu+ subgroup showed greater alpha source activations topographically widespread. On the contrary, in relation to the ADMCI-Edu- subgroup, the ADMCI-Edu+ subgroup displayed lower alpha source activations topographically widespread. Furthermore, the 2 ADMCI subgroups had matched cerebrospinal AD diagnostic biomarkers, brain gray-white matter measures, and neuropsychological scores. The current findings suggest that a high CR may be related to changes in rsEEG alpha rhythms in Nold and ADMCI persons. These changes may underlie neuroprotective effects in Nold seniors and subtend functional compensatory mechanisms unrelated to brain structure alterations in ADMCI patients.
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http://dx.doi.org/10.1093/cercor/bhaa356DOI Listing
March 2021

Timed Up and Go Test With a Cognitive Task: Correlations With Neuropsychological Measures in People With Parkinson's Disease.

Cureus 2020 Sep 22;12(9):e10604. Epub 2020 Sep 22.

Physical Therapy and Rehabilitation, Dokuz Eylül University, Izmir, TUR.

Background The Timed Up and Go (TUG) test is a simple and widely used clinical test for the assessment of lower extremity function, balance, mobility, and fall risk in various populations. The TUG has been found as a valid and reliable measure in people with Parkinson's disease (PD). Besides, the addition of a cognitive task to the TUG (TUG-cognitive) enhances predictive validity related to fall risk in people with PD. However, further investigation is needed about the correlations of the TUG-cognitive test with neuropsychological measures in people with PD. Methods Thirty-three people with PD [modified Hoehn and Yahr scale, median (min-max)=2.5 (1.0-3.0)] participated in this cross-sectional study. The TUG was administered in the traditional way and with a cognitive task (counting backward by three from any number between 20 and 100). Neuropsychological measures included the Montreal Cognitive Assessment (MoCA), Trail Making Test (TMT), and the Simple Reaction Time (SRT) test for stepping. The self-reported number of falls in the last six months was also recorded. Results The TUG-cognitive [13.1 (SD=8.5) seconds] was significantly longer than the TUG-traditional [12.2 (SD=8.1) seconds] (p<0.01). The TUG-cognitive significantly correlated with the MoCA [(rho=-0.712), TMT part A (TMT-A; rho=0.722), TMT part B (TMT-B; rho=0.694), SRT (rho=0.794), and number of falls (rho=0.960)] (p<0.01). The TUG-traditional also significantly correlated with the MoCA (rho=-0.682), TMT-A (rho=0.684), TMT-B (rho=0.746), SRT (rho=0.755), and number of falls (rho=0.702) (p<0.01). Conclusion Both the TUG-cognitive and TUG-traditional strongly correlated with neuropsychological measures; while the correlations were slightly stronger for the TUG-cognitive, the difference was not significant. The TUG-cognitive can be used in the clinical practice as a simple and more informative alternative to the TUG-traditional in people with PD.
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http://dx.doi.org/10.7759/cureus.10604DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7584288PMC
September 2020

Resting-state electroencephalographic delta rhythms may reflect global cortical arousal in healthy old seniors and patients with Alzheimer's disease dementia.

Int J Psychophysiol 2020 Dec 17;158:259-270. Epub 2020 Oct 17.

Department of Physiology and Pharmacology "Vittorio Erspamer", Sapienza University of Rome, Rome, Italy.

Extending Başar's theory of event-related EEG oscillations, here we hypothesize that even in quiet wakefulness, transient increases in delta rhythms may enhance global cortical arousal as revealed by the desynchronization of alpha rhythms in normal (Nold) seniors with some derangement in Alzheimer's disease dementia (ADD). Clinical and EEG datasets in 100 ADD and 100 Nold individuals matched as demography, education, and gender were taken from an international archive. Standard delta (< 4 Hz) and alpha1 (8-10.5 Hz) bands were used for the main analysis, while alpha2 (10.5-13 Hz), theta (4-8 Hz), beta1 (13-20 Hz), beta2 (20-35 Hz), and gamma (35-40 Hz) served as controls. In the interpretation, the higher the alpha1 power (density), the lower that arousal. As expected, when compared to the Nold group, the ADD group showed higher global (scalp) power density at the delta-theta band and lower global power density at the alpha-beta bands. As novel findings, we observed that: (1) in the Nold group, the global delta and alpha1-2 power were negatively and linearly correlated; (2) in the ADD group, this correlation was just marginal; and (3) in both Nold and AD groups, the EEG epochs with the highest delta power (median value for stratification) were associated with the lowest global alpha1 power. This effect was related to eLORETA freeware solutions showing maximum alpha1 source activations in posterior cortical regions. These results suggest that even in quiet wakefulness, delta and alpha rhythms are related to each other, and ADD partially affects this cross-band neurophysiological mechanism.
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http://dx.doi.org/10.1016/j.ijpsycho.2020.08.012DOI Listing
December 2020

Abnormalities of resting-state EEG in patients with prodromal and overt dementia with Lewy bodies: Relation to clinical symptoms.

Clin Neurophysiol 2020 11 23;131(11):2716-2731. Epub 2020 Sep 23.

Department of Neurology, School of Medicine, Istanbul Medipol University, Istanbul, Turkey.

Objective: Here we tested if cortical sources of resting state electroencephalographic (rsEEG) rhythms may differ in sub-groups of patients with prodromal and overt dementia with Lewy bodies (DLB) as a function of relevant clinical symptoms.

Methods: We extracted clinical, demographic and rsEEG datasets in matched DLB patients (N = 60) and control Alzheimer's disease (AD, N = 60) and healthy elderly (Nold, N = 60) seniors from our international database. The eLORETA freeware was used to estimate cortical rsEEG sources.

Results: As compared to the Nold group, the DLB and AD groups generally exhibited greater spatially distributed delta source activities (DLB > AD) and lower alpha source activities posteriorly (AD > DLB). As compared to the DLB "controls", the DLB patients with (1) rapid eye movement (REM) sleep behavior disorders showed lower central alpha source activities (p < 0.005); (2) greater cognitive deficits exhibited higher parietal and central theta source activities as well as higher central, parietal, and occipital alpha source activities (p < 0.01); (3) visual hallucinations pointed to greater parietal delta source activities (p < 0.005).

Conclusions: Relevant clinical features were associated with abnormalities in spatial and frequency features of rsEEG source activities in DLB patients.

Significance: Those features may be used as neurophysiological surrogate endpoints of clinical symptoms in DLB patients in future cross-validation prospective studies.
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http://dx.doi.org/10.1016/j.clinph.2020.09.004DOI Listing
November 2020

Biomarker counseling, disclosure of diagnosis and follow-up in patients with mild cognitive impairment: A European Alzheimer's disease consortium survey.

Int J Geriatr Psychiatry 2021 02 16;36(2):324-333. Epub 2020 Sep 16.

Servicio de geriatria, Hospital Universitario Ramon y Cajal, Madrid, Spain.

Objectives: Mild cognitive impairment (MCI) is associated with an increased risk of further cognitive decline, partly depending on demographics and biomarker status. The aim of the present study was to survey the clinical practices of physicians in terms of biomarker counseling, management, and follow-up in European expert centers diagnosing patients with MCI.

Methods: An online email survey was distributed to physicians affiliated with European Alzheimer's disease Consortium centers (Northern Europe: 10 centers; Eastern and Central Europe: 9 centers; and Southern Europe: 15 centers) with questions on attitudes toward biomarkers and biomarker counseling in MCI and dementia. This included postbiomarker counseling and the process of diagnostic disclosure of MCI, as well as treatment and follow-up in MCI.

Results: The response rate for the survey was 80.9% (34 of 42 centers) across 20 countries. A large majority of physicians had access to biomarkers and found them useful. Pre- and postbiomarker counseling varied across centers, as did practices for referral to support groups and advice on preventive strategies. Less than half reported discussing driving and advance care planning with patients with MCI.

Conclusions: The variability in clinical practices across centers calls for better biomarker counseling and better training to improve communication skills. Future initiatives should address the importance of communicating preventive strategies and advance planning.
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http://dx.doi.org/10.1002/gps.5427DOI Listing
February 2021

Investigation of Factors Affecting Apathy in Three Major Types of Dementia.

Noro Psikiyatr Ars 2020 Jun 7;57(2):120-125. Epub 2019 Aug 7.

Department of Neurology, Dokuz Eylül University School of Medicine, İzmir, Turkey.

Introducion: Apathy is an important factor in the clinical management of dementia, as it has been associated with poor disease outcome, reduced daily functioning and caregiver distress. Considering apathy as a problem that needs to be managed and knowing the factors affecting apathy will enable appropriate initiatives to be planned. This study was conducted to compare apathy across three types of dementia and determine the factors affecting apathy for each of the three types of dementia.

Methods: The sample consisted of 46 patients with Alzheimer's disease (AD), 31 patients with frontotemporal dementia (FTD) and 29 patients with vascular dementia (VaD). Apathy was assessed using the Neuropsychiatric Inventory-apathy subscale (NPI), dementia severity was assessed using the Clinical Dementia Rating Scale (CDR), cognitive status was assessed using the Mini Mental Status Examination (MMSE) functional ability was measured with the Katz Index of Independence in Activities of Daily Living (ADL) and the Lawton-Brody Instrumental Activities of Daily Living (IADL). This is a descriptive and cross-sectional study.

Results: Significant differences were found between the apathy score of three types of dementia. Cognitive impairment correlated significantly with the apathy score in AD and VaD. Functionality scores and severity of dementia showed a significant correlation with apathy in each group. No statistically significant relationship was detected between age, gender and apathy. Multiple regression analyses show that apathy scores correlated with IADL in patients with AD.

Conclusion: This study demonstrated that apathy is very common symptom in patients with FTD as well as patients with AD and VaD. Health professionals need to be aware of recognize apathy. Patients should be assessed for apathy regardless of dementia types, age and gender.
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http://dx.doi.org/10.29399/npa.22964DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7285638PMC
June 2020

Evoked and induced EEG oscillations to visual targets reveal a differential pattern of change along the spectrum of cognitive decline in Alzheimer's Disease.

Int J Psychophysiol 2020 09 6;155:41-48. Epub 2020 Jun 6.

Istanbul University, Istanbul Faculty of Medicine, Department of Physiology, Turkey; Istanbul University, Hulusi Behcet Life Sciences Research Center, Turkey. Electronic address:

In recent years, quantitative variables derived from the electroencephalogram (EEG) attract an increasing interest for the evaluation of neurodegenerative diseases, as EEG registers the neuro-electric activity with a high temporal resolution and provides a cost-effective and easily accessible, non-invasive method. Event-related oscillations (EROs) as oscillatory responses in the EEG to specific events further provide the possibility to track the cognitive decline in a task-specific manner. Current study in search for potential ERO biomarkers to distinguish different stages of cognitive decline along the Alzheimer's Disease (AD) continuum re-analyzed a combined set of data collected and analyzed in previous studies by Başar and coworkers. Target responses of a visual oddball experiment recorded from 33 AD patients, 46 Mild Cognitive Impairment (MCI) patients and 48 age, gender, and education matched normal elderly controls were analyzed for both evoked (phase-locked) and total (phase-locked + non-phase-locked) ERO powers in delta, theta, alpha, beta and gamma bands by applying continuous wavelet transform (WT) on averaged and single trial data, respectively. The cluster-based nonparametric permutation test implemented in the FieldTrip toolbox revealed significant differences among the three groups. While the total delta and theta responses already significantly declined in the MCI stage with further spatial expansion of the decline in AD, the evoked delta response reached a statistically significant reduction level in the AD stage. We obtained no significant difference among groups for alpha, beta and gamma frequency bands. These results suggest that total delta and theta EROs to oddball targets may be useful for early detection of the disease in MCI stage, while the evoked delta response allows detecting the conversion to AD.
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http://dx.doi.org/10.1016/j.ijpsycho.2020.06.001DOI Listing
September 2020

Abnormalities in auditory and visual cognitive processes are differentiated with theta responses in patients with Parkinson's disease with and without dementia.

Int J Psychophysiol 2020 07 24;153:65-79. Epub 2020 Apr 24.

Dokuz Eylül University Medical School, Department of Neurology, Izmir, Turkey; Dokuz Eylül University, Brain Dynamics Multidisciplinary Research Center, Izmir, Turkey.

The research on the abnormalities of event-related oscillations in Parkinson's disease (PD) was mostly studied with cognitively normal patients. The present study aims to show the adverse effects of cognitive decline in PD patients via the EEG-Brain Oscillations approach by comparing the electrophysiological responses in two modalities, i.e. auditory, and visual in which PD group show deficit. We conducted a study in which we analyzed event-related theta power and phase-locking during auditory and visual oddball paradigm. Cognitively normal PD (PDCN) patients (N = 15), PD with mild cognitive impairment (PDMCI) patients (N = 22), PD dementia (PDD) patients (N = 11) and healthy controls (HC) (N = 17) were included in the study. Neuropsychological assessments were applied to all participants. There was a gradual decrease in scores of neuropsychological tests (HC, PDCN, PDMCI, PDD, respectively). Most of the neuropsychological test scores of the participants were highly correlated with the theta power and theta phase locking values, especially over frontal-central areas. HC had higher theta phase-locking and power in comparison to PDMCI and PDD. The differentiation between HC and PDCN was specific to frontal-central areas. Theta power and theta phase-locking were decreased overall locations in PDMCI and PDD both during visual and auditory oddball paradigms compared with PDCN. The results indicate that theta responses in PD patients decreased gradually as the cognitive decline increased. We can conclude that complex abnormalities in their neurotransmitter and neuronal signal systems that occur with the progression of the disease could be responsible for these results.
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http://dx.doi.org/10.1016/j.ijpsycho.2020.04.016DOI Listing
July 2020

Abnormal cortical neural synchronization mechanisms in quiet wakefulness are related to motor deficits, cognitive symptoms, and visual hallucinations in Parkinson's disease patients: an electroencephalographic study.

Neurobiol Aging 2020 07 12;91:88-111. Epub 2020 Mar 12.

Department of Biophysics, International School of Medicine, Istanbul Medipol University, Istanbul, Turkey.

Compared with Alzheimer's disease (AD), Parkinson's disease (PD) shows peculiar clinical manifestations related to vigilance (i.e., executive cognitive deficits and visual hallucinations) that may be reflected in resting-state electroencephalographic rhythms. To test this hypothesis, clinical and resting-state electroencephalographic rhythms in age-, sex-, and education-matched PD patients (N = 136) and Alzheimer's disease patients (AD, N = 85), and healthy older participants (Nold, N = 65), were available from an international archive. Electroencephalographic sources were estimated by eLORETA software. The results are as follows: (1) compared to the Nold participants, the AD and PD patients showed higher widespread delta source activities (PD > AD) and lower posterior alpha source activities (AD > PD); (2) the PD patients with the most pronounced motor deficits exhibited very low alpha source activities in widespread cortical regions; (3) the PD patients with the strongest cognitive deficits showed higher alpha source activities in widespread cortical regions; and (4) compared to the PD patients without visual hallucinations, those with visual hallucinations were characterized by higher posterior alpha sources activities. These results suggest that in PD patients resting in quiet wakefulness, abnormalities in cortical neural synchronization at alpha frequencies are differently related to cognitive, motor, and visual hallucinations. Interestingly, parallel PD neuropathological processes may have opposite effects on cortical neural synchronization mechanisms generating cortical alpha rhythms in quiet wakefulness.
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http://dx.doi.org/10.1016/j.neurobiolaging.2020.02.029DOI Listing
July 2020

Brain-predicted age difference score is related to specific cognitive functions: a multi-site replication analysis.

Brain Imaging Behav 2021 Feb;15(1):327-345

Trinity College Institute of Neuroscience, Trinity College Dublin, Lloyd Building, Dublin 2, Ireland.

Brain-predicted age difference scores are calculated by subtracting chronological age from 'brain' age, which is estimated using neuroimaging data. Positive scores reflect accelerated ageing and are associated with increased mortality risk and poorer physical function. To date, however, the relationship between brain-predicted age difference scores and specific cognitive functions has not been systematically examined using appropriate statistical methods. First, applying machine learning to 1359 T1-weighted MRI scans, we predicted the relationship between chronological age and voxel-wise grey matter data. This model was then applied to MRI data from three independent datasets, significantly predicting chronological age in each dataset: Dokuz Eylül University (n = 175), the Cognitive Reserve/Reference Ability Neural Network study (n = 380), and The Irish Longitudinal Study on Ageing (n = 487). Each independent dataset had rich neuropsychological data. Brain-predicted age difference scores were significantly negatively correlated with performance on measures of general cognitive status (two datasets); processing speed, visual attention, and cognitive flexibility (three datasets); visual attention and cognitive flexibility (two datasets); and semantic verbal fluency (two datasets). As such, there is firm evidence of correlations between increased brain-predicted age differences and reduced cognitive function in some domains that are implicated in cognitive ageing.
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http://dx.doi.org/10.1007/s11682-020-00260-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7500565PMC
February 2021

What electrophysiology tells us about Alzheimer's disease: a window into the synchronization and connectivity of brain neurons.

Neurobiol Aging 2020 01 19;85:58-73. Epub 2019 Sep 19.

Gladstone Institute of Neurological Disease, San Francisco, CA, USA.

Electrophysiology provides a real-time readout of neural functions and network capability in different brain states, on temporal (fractions of milliseconds) and spatial (micro, meso, and macro) scales unmet by other methodologies. However, current international guidelines do not endorse the use of electroencephalographic (EEG)/magnetoencephalographic (MEG) biomarkers in clinical trials performed in patients with Alzheimer's disease (AD), despite a surge in recent validated evidence. This position paper of the ISTAART Electrophysiology Professional Interest Area endorses consolidated and translational electrophysiological techniques applied to both experimental animal models of AD and patients, to probe the effects of AD neuropathology (i.e., brain amyloidosis, tauopathy, and neurodegeneration) on neurophysiological mechanisms underpinning neural excitation/inhibition and neurotransmission as well as brain network dynamics, synchronization, and functional connectivity, reflecting thalamocortical and corticocortical residual capacity. Converging evidence shows relationships between abnormalities in EEG/MEG markers and cognitive deficits in groups of AD patients at different disease stages. The supporting evidence for the application of electrophysiology in AD clinical research as well as drug discovery pathways warrants an international initiative to include the use of EEG/MEG biomarkers in the main multicentric projects planned in AD patients, to produce conclusive findings challenging the present regulatory requirements and guidelines for AD studies.
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http://dx.doi.org/10.1016/j.neurobiolaging.2019.09.008DOI Listing
January 2020

A new tool to assess amnestic mild cognitive impairment in Turkish older adults: virtual supermarket (VSM).

Neuropsychol Dev Cogn B Aging Neuropsychol Cogn 2020 09 4;27(5):639-653. Epub 2019 Sep 4.

Department of Neurology, School of Medicine, Dokuz Eylul University , Izmir, Turkey.

The purpose of this study was to investigate cognitive functioning by administering the Virtual Supermarket (VSM) test in patients with amnestic mild cognitive impairment (aMCI, N = 37) and age and education-matched healthy controls (HCs, N = 52). An extensive neuropsychological test battery and the VSM were administered to all participants. The aMCI group exhibited lower performance and required more time to complete the VSM compared to HCs. Also, aMCI-Multiple Domain (aMCI-MD) patients performed worse in the "Correct Types", "Correct Quantities", "Bought Unlisted", "Correct Money" variables compared to HCs. Moreover, aMCI-SD patients displayed lower performance in "Bought Unlisted" and "Correct Money" variables compared to HCs. The VSM variables correlated with established neuropsychological test scores. The VSM test was found to discriminate between aMCI and HCs with a correct classification rate (CCR) of 81%. This is a preliminary study showing that the VSM is a valid, brief and user-friendly test. .
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http://dx.doi.org/10.1080/13825585.2019.1663146DOI Listing
September 2020

Electrophysiological evidence of altered facial expressions recognition in Alzheimer's disease: A comprehensive ERP study.

Clin Neurophysiol 2019 10 12;130(10):1813-1824. Epub 2019 Jul 12.

Department of Neurosciences, Institute of Health Sciences, Dokuz Eylul University, Izmir, Turkey; Dokuz Eylul University Medical School, Department of Neurology, Izmir, Turkey; Dokuz Eylul University, Brain Dynamics Multidisciplinary Research Center, Izmir, Turkey.

Objectives: The present study aims to evaluate the amplitude and latency of event-related potentials (ERPs) P100, N170, VPP and N230 in individuals with Alzheimer's disease (AD) compared to healthy elderly controls, using a passive viewing task of emotional facial expressions.

Methods: Twenty-four individuals with mild to moderate AD and 23 demographically matched healthy elderly controls were included in the study. ERP P100, N170, VPP and N230 amplitude and latency values were compared between groups.

Results: The categorization of emotional facial expressions was intact; yet, increased P100 amplitude and latency, decreased N170 amplitude, and increased VPP amplitude were observed in AD compared to controls. Increased N230 amplitude and latency were observed in response to angry expressions, while neutral expressions elicited decreased amplitude and latency.

Conclusions: Increased P100 amplitude and latency may reflect reduced amygdala volume and disruptions in the visual system, while decreased N170 and increased VPP amplitudes may reflect impaired perceptual processing, mitigated by a greater involvement of prefrontal areas for task performance in AD.

Significance: This study is the first to report a complex pattern of ERPs to emotional facial expressions in individuals with AD.
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http://dx.doi.org/10.1016/j.clinph.2019.06.229DOI Listing
October 2019

Impairment in recognition of emotional facial expressions in Alzheimer's disease is represented by EEG theta and alpha responses.

Psychophysiology 2019 11 2;56(11):e13434. Epub 2019 Jul 2.

Department of Neurology, International School of Medicine, Dokuz Eylül University Medical School, Izmir, Turkey.

Behavioral studies have shown that the recognition of facial expressions may be impaired in patients with Alzheimer's disease (AD). The identification and recognition of a facial expression might be represented by event-related brain oscillations. The present study aims to analyze EEG event-related oscillations and determine the electrophysiological indicators of impaired facial expression recognition in AD patients. EEGs of 30 healthy controls and 30 AD patients were recorded during their perception of three different facial expressions (angry, happy, neutral). Event-related power spectrum and phase locking were analyzed in the theta (4-7) and alpha (8-13 Hz) frequency bands with the EEGLAB open toolbox. There was a significant facial Expression × Group interaction (p < 0.05) for the theta power spectrum; the healthy control group had higher theta power than the AD group during the perception of angry facial expressions (p < 0.05). There was a significant hemisphere difference between the two groups (p < 0.05). There was a right hemisphere alpha power dominance in healthy subjects. However, AD patients did not have this alpha power asymmetry. The present study, for the first time in the literature, presents the electrophysiological indicators of impaired recognition of facial expression in AD patients. The current study could be a basis for future studies that will analyze emotional processing in different kinds of dementia patients, and this study may have provided indicators of electrophysiological correlates of behavioral problems observed in clinical practice.
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http://dx.doi.org/10.1111/psyp.13434DOI Listing
November 2019

Mild cognitive impairment in Parkinson's disease is associated with decreased P300 amplitude and reduced putamen volume.

Clin Neurophysiol 2019 08 4;130(8):1208-1217. Epub 2019 May 4.

Department of Neurosciences, Institute of Health Sciences, Dokuz Eylul University, Izmir 35340, Turkey; Department of Neurology, Dokuz Eylul University Medical School, Izmir 35340, Turkey; Brain Dynamics Multidisciplinary Research Center, Dokuz Eylul University, Izmir 35340, Turkey. Electronic address:

Objective: Functional and structural brain alterations of cognitively normal Parkinson's disease (PD-CN) and Parkinson's disease mild cognitive impairment (PD-MCI) patients were investigated using event-related potentials (ERP) P300 and volumetric magnetic resonance imaging (MRI) parameters.

Methods: Twenty three patients with PD-CN, 21 with PD-MCI, and 23 demographically-matched healthy controls were included. EEGs were recorded using a visual oddball task and mean amplitude and peak latency values of P300 were measured. Gray matter volumes (GMV) of thalamus, caudate, putamen, globus pallidus, hippocampus, amygdala and nucleus accumbens were obtained using FMRIB Integrated Registration and Segmentation Tool. Correlations among P300, subcortical GMV and cognitive performances were assessed.

Results: PD-CN patients demonstrated reduced P300 amplitudes compared to healthy controls. PD-MCI patients had lower P300 amplitudes than both PD-CN patients and controls and reduced volumes of the putamen compared to controls. Both putamen volumes and P300 amplitudes showed moderate associations with executive functions.

Conclusions: Our findings support that P300 amplitude may be a useful marker for the detection of preclinical changes before the appearance of cognitive and structural deterioration in PD, as shown by decreased frontal P300 amplitudes in PD-CN. The reduction further spread to centro-parietal areas in PD-MCI patients, which was accompanied by lower putamen volumes.

Significance: This study is the first to report on changes in ERP P300 amplitude and subcortical volume in well-matched samples of PD-CN, PD-MCI and healthy controls.
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http://dx.doi.org/10.1016/j.clinph.2019.04.314DOI Listing
August 2019

The difference of mild cognitive impairment in Parkinson's disease from amnestic mild cognitive impairment: Deeper power decrement and no phase-locking in visual event-related responses.

Int J Psychophysiol 2019 05 7;139:48-58. Epub 2019 Mar 7.

REMER, Clinical Electrophysiology, Neuroimaging and Neuromodulation Lab, Istanbul Medipol University, Istanbul, Turkey; Department of Biophysics, School of International Medicine, Istanbul Medipol University, Istanbul, Turkey.

Event-related oscillatory responses reflect the cognitive status in many neuropsychiatric conditions including mild cognitive impairment (MCI). In this study, a total of 30 patients with amnestic MCI (aMCI) and 25 patients with MCI of Parkinson's disease (PD-MCI) were compared with 28 aged-, gender-, education-matched healthy control (HC) participants using visual event-related delta, theta, alpha oscillatory responses by methods of event-related spectral perturbation and inter-trial coherence. PD-MCI and aMCI groups commonly share a decreased theta power, but all electrophysiological deviations from the controls were more prominent in PD-MCI than aMCI in all frequency bands. Additionally, decreased phase-locking in all studied frequency bands was encountered only in PD-MCI group, but it was preserved in aMCI. These findings indicate that visual networks in PD-MCI are more severely affected than aMCI. Reduced phase-locking in PD-MCI may possibly relate to dysfunctioning subcortical modulating centers that take a role in the generation of event-related responses.
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http://dx.doi.org/10.1016/j.ijpsycho.2019.03.002DOI Listing
May 2019

Abnormalities of functional cortical source connectivity of resting-state electroencephalographic alpha rhythms are similar in patients with mild cognitive impairment due to Alzheimer's and Lewy body diseases.

Neurobiol Aging 2019 05 24;77:112-127. Epub 2019 Jan 24.

Department of Biophysics, International School of Medicine, Istanbul Medipol University, Istanbul, Turkey.

Previous evidence has shown different resting-state eyes-closed electroencephalographic delta (<4 Hz) and alpha (8-10.5 Hz) source connectivity in subjects with dementia due to Alzheimer's (ADD) and Lewy body (DLB) diseases. The present study tested if the same differences may be observed in the prodromal stages of mild cognitive impairment (MCI). Here, clinical and resting-state eyes-closed electroencephalographic data in age-, gender-, and education-matched 30 ADMCI, 23 DLBMCI, and 30 healthy elderly (Nold) subjects were available in our international archive. Mini-Mental State Evaluation (MMSE) score was matched in the ADMCI and DLBMCI groups. The eLORETA freeware estimated delta and alpha source connectivity by the tool called lagged linear connectivity (LLC). Area under receiver operating characteristic curve (AUROCC) indexed the classification accuracy among individuals. Results showed that widespread interhemispheric and intrahemispheric LLC solutions in alpha sources were abnormally lower in both MCI groups compared with the Nold group, but with no differences were found between the 2 MCI groups. AUROCCs of LLC solutions in alpha sources exhibited significant accuracies (0.72-0.75) in the discrimination of Nold versus ADMCI-DLBMCI individuals, but not between the 2 MCI groups. These findings disclose similar abnormalities in ADMCI and DLBMCI patients as revealed by alpha source connectivity. It can be speculated that source connectivity mostly reflects common cholinergic impairment in prodromal state of both AD and DLB, before a substantial dopaminergic derangement in the dementia stage of DLB.
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http://dx.doi.org/10.1016/j.neurobiolaging.2019.01.013DOI Listing
May 2019

Evaluation of Matrix Metalloproteinase-2 (MMP-2) and -9 (MMP-9) and Their Tissue Inhibitors (TIMP-1 and TIMP-2) in Plasma from Patients with Neurodegenerative Dementia.

J Alzheimers Dis 2018 ;66(3):1265-1273

Thoracic and Gastrointestinal Oncology Branch, National Cancer Institute/NIH, Bethesda, MD, USA.

Matrix metalloproteinases (MMPs) are substantial regulators of learning and memory and might be involved in neurodegeneration. It is known that MMPs are involved in pathogenesis of Alzheimer's disease (AD) and are particularly involved in the amyloid-β processing pathway. However, information on circulating levels of these proteins and their tissue inhibitors (TIMPs) in AD and other neurodegenerative dementia (ND) diseases such as dementia with Lewy bodies (DLB) and frontotemporal dementia (FTD) is not clear. Therefore, this study was directed toward finding out how plasma levels of MMP-2, MMP-9, TIMP-1, and TIMP-2 vary in AD, DLB, and FTD; and investigating the correlation of the levels of MMPs and their inhibitors with clinical parameters of the patients. MMP-2, MMP-9, TIMP-1, and TIMP-2 levels were measured by enzyme linked immunosorbent assay (ELISA). Plasma MMP-2 levels were significantly lower in all the patient groups than in the age-matched healthy controls (HCs) (p < 0.05). MMP-9 levels were significantly lower in the FTD patients than in the HCs (p < 0.05). Also, TIMP-1 levels were lower in the AD and FTD patients than in the HCs (p < 0.05). TIMP-2 levels were similar in all the groups. These findings highlight the importance of circulating MMPs in ND and suggest that MMPs and their inhibitors might play a role in impaired amyloid-β peptide metabolism which is responsible for the genesis and progression of ND. Furthermore, measurement of MMP-2 and MMP-9 and their inhibitors may be of great importance for large scale basic research and clinical studies of ND.
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http://dx.doi.org/10.3233/JAD-180752DOI Listing
November 2019

Levodopa may affect cortical excitability in Parkinson's disease patients with cognitive deficits as revealed by reduced activity of cortical sources of resting state electroencephalographic rhythms.

Neurobiol Aging 2019 01 30;73:9-20. Epub 2018 Aug 30.

Department of Neurology, University of Istanbul-Medipol, Istanbul, Turkey.

We hypothesized that dopamine neuromodulation might affect cortical excitability in Parkinson's disease (PD) patients set in quiet wakefulness, as revealed by resting state eyes-closed electroencephalographic (rsEEG) rhythms at alpha frequencies (8-12 Hz). Clinical and rsEEG rhythms in PD with dementia (N = 35), PD with mild cognitive impairment (N = 50), PD with normal cognition (N = 35), and normal (N = 50) older adults were available from an international archive. Cortical rsEEG sources were estimated by exact low-resolution brain electromagnetic tomography. Compared with the normal older group, the PD groups showed reduced occipital alpha sources and increased widespread delta (<4 Hz) sources. Widespread frontal and temporal alpha sources exhibited an increase in PD with dementia compared with PD with mild cognitive impairment and PD with normal cognition groups, as function of dopamine depletion severity, typically greater in the former than the latter groups. A daily dose of levodopa induced a widespread reduction in cortical delta and alpha sources in a subgroup of 13 PD patients under standard chronic dopaminergic regimen. In PD patients in quiet wakefulness, alpha cortical source activations may reflect an excitatory effect of dopamine neuromodulation.
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http://dx.doi.org/10.1016/j.neurobiolaging.2018.08.010DOI Listing
January 2019

Electrophysiological and neuropsychological outcomes of severe obstructive sleep apnea: effects of hypoxemia on cognitive performance.

Cogn Neurodyn 2018 Oct 25;12(5):471-480. Epub 2018 May 25.

1Department of Neurosciences, Institute of Health Sciences, Dokuz Eylül University, 35340 Izmir, Turkey.

Obstructive sleep apnea syndrome (OSAS) is a sleep disorder characterized with upper airway obstructions. Some studies showed cognitive and electrophysiological changes in patients with OSAS; however, contradictory results were also reported. The purpose of the present study was twofold: (1) to investigate cognitive changes in severe OSAS patients by using neuropsychological tests and electrophysiological methods together, (2) to investigate influence of hypoxemia levels on cognition. Fifty-four severe OSAS patients and 34 age-, gender- and education matched healthy subjects were participated. OSAS patients were further divided into two subgroups according to minimum oxygen saturation levels. All participants underwent a detailed neuropsychological test battery. A classical visual oddball task was used to elicit ERP P300 and mean P300 amplitudes were measured from F, C and P electrode sites. OSAS patients showed reduced mean P300 amplitudes up to 43-51% on all electrode sites compared to healthy controls. Subgroup analysis revealed significant differences in neuropsychological test scores between healthy controls and high hypoxemia OSAS group, as well as between low and high hypoxemia groups. Moreover, both low and high hypoxemia OSAS groups had lower P300 amplitudes compared with healthy controls. P300 amplitudes showed a gradual decline in parallel with increasing hypoxemia severity; however, the difference between high and low hypoxemia OSAS groups did not reach significance. Moderate correlations were found between sleep parameters, neuropsychological test scores and P300 amplitudes. These results suggest that electrophysiological measures could be better indicators of cognitive changes than neuropsychological tests in OSAS, particularly in mildly affected patients.
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http://dx.doi.org/10.1007/s11571-018-9487-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6139099PMC
October 2018

Cognitive Impairment in Parkinson's Disease Is Reflected with Gradual Decrease of EEG Delta Responses during Auditory Discrimination.

Front Psychol 2018 21;9:170. Epub 2018 Feb 21.

Brain Dynamics, Cognition and Complex Systems Research Center, Istanbul Kultur University, Istanbul, Turkey.

Parkinson's disease (PD) is a neurodegenerative disease that is characterized by loss of dopaminergic neurons in the substantia nigra. Mild Cognitive impairment (MCI) and dementia may come along with the disease. New indicators are necessary for detecting patients that are likely to develop dementia. Electroencephalogram (EEG) Delta responses are one of the essential electrophysiological indicators that could show the cognitive decline. Many research in literature showed an increase of delta responses with the increased cognitive load. Furthermore, delta responses were decreased in MCI and Alzheimer disease in comparison to healthy controls during cognitive paradigms. There was no previous study that analyzed the delta responses in PD patients with cognitive deficits. The present study aims to fulfill this important gap. 32 patients with Parkinson's disease (12 of them were without any cognitive deficits, 10 of them were PD with MCI, and 10 of them were PD with dementia) and 16 healthy subjects were included in the study. Auditory simple stimuli and Auditory Oddball Paradigms were applied. The maximum amplitudes of each subject's delta response (0.5-3.5 Hz) in 0-600 ms were measured for each electrode and for each stimulation. There was a significant stimulation × group effect [ = 3,21; < 0.015; [Formula: see text] = 0.180], which showed that the difference between groups was specific to the stimulation. Patients with Parkinson's disease (including PD without cognitive deficit, PD with MCI, and PD with dementia) had reduced delta responses than healthy controls upon presentation of target stimulation ( < 0.05, for all comparisons). On the other hand, this was not the case for non-target and simple auditory stimulation. Furthermore, delta responses gradually decrease according to the cognitive impairment in patients with PD. : The results of the present study showed that cognitive decline in PD could be represented with decreased event related delta responses during cognitive stimulations. Furthermore, the present study once more strengthens the hypothesis that decrease of delta oscillatory responses could be the candidate of a general electrophysiological indicator for cognitive impairment.
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http://dx.doi.org/10.3389/fpsyg.2018.00170DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5826339PMC
February 2018

Functional cortical source connectivity of resting state electroencephalographic alpha rhythms shows similar abnormalities in patients with mild cognitive impairment due to Alzheimer's and Parkinson's diseases.

Clin Neurophysiol 2018 04 31;129(4):766-782. Epub 2018 Jan 31.

Department of Neurosciences, Dokuz Eylül University, Izmir, Turkey; Department of Neurology, Dokuz Eylül University Medical School, Izmir, Turkey.

Objective: This study tested the hypothesis that markers of functional cortical source connectivity of resting state eyes-closed electroencephalographic (rsEEG) rhythms may be abnormal in subjects with mild cognitive impairment due to Alzheimer's (ADMCI) and Parkinson's (PDMCI) diseases compared to healthy elderly subjects (Nold).

Methods: rsEEG data had been collected in ADMCI, PDMCI, and Nold subjects (N = 75 for any group). eLORETA freeware estimated functional lagged linear connectivity (LLC) from rsEEG cortical sources. Area under receiver operating characteristic (AUROC) curve indexed the accuracy in the classification of Nold and MCI individuals.

Results: Posterior interhemispheric and widespread intrahemispheric alpha LLC solutions were abnormally lower in both MCI groups compared to the Nold group. At the individual level, AUROC curves of LLC solutions in posterior alpha sources exhibited moderate accuracies (0.70-0.72) in the discrimination of Nold vs. ADMCI-PDMCI individuals. No differences in the LLC solutions were found between the two MCI groups.

Conclusions: These findings unveil similar abnormalities in functional cortical connectivity estimated in widespread alpha sources in ADMCI and PDMCI. This was true at both group and individual levels.

Significance: The similar abnormality of alpha source connectivity in ADMCI and PDMCI subjects might reflect common cholinergic impairment.
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http://dx.doi.org/10.1016/j.clinph.2018.01.009DOI Listing
April 2018

Abnormalities of Resting State Cortical EEG Rhythms in Subjects with Mild Cognitive Impairment Due to Alzheimer's and Lewy Body Diseases.

J Alzheimers Dis 2018 ;62(1):247-268

Department of Biophysics, Istanbul Medipol University, Istanbul, Turkey.

The present study tested the hypothesis that cortical sources of resting state eyes-closed electroencephalographic (rsEEG) rhythms reveal different abnormalities in cortical neural synchronization in groups of patients with mild cognitive impairment due to Alzheimer's disease (ADMCI) and dementia with Lewy bodies (DLBMCI) as compared to cognitively normal elderly (Nold) subjects. Clinical and rsEEG data in 30 ADMCI, 23 DLBMCI, and 30 Nold subjects were available in an international archive. Age, gender, and education were carefully matched in the three groups. The Mini-Mental State Evaluation (MMSE) score was matched between the ADMCI and DLBMCI groups. Individual alpha frequency peak (IAF) was used to determine the delta, theta, alpha1, alpha2, and alpha3 frequency band ranges. Fixed beta1, beta2, and gamma bands were also considered. eLORETA estimated the rsEEG cortical sources. Receiver operating characteristic curve (ROCC) classified these sources across individuals. Compared to Nold, IAF showed marked slowing in DLBMCI and moderate in ADMCI. Furthermore, the posterior alpha 2 and alpha 3 source activities were more abnormal in the ADMCI than the DLBMCI group, while widespread delta source activities were more abnormal in the DLBMCI than the ADMCI group. The posterior delta and alpha sources correlated with the MMSE score and correctly classified the Nold and MCI individuals (area under the ROCC >0.85). In conclusion, the ADMCI and DLBMCI patients showed different features of cortical neural synchronization at delta and alpha frequencies underpinning brain arousal and vigilance in the quiet wakefulness. Future prospective cross-validation studies will have to test the clinical validity of these rsEEG markers.
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http://dx.doi.org/10.3233/JAD-170703DOI Listing
March 2019