Görsev Yener

Izmir University of Economics Faculty of Medicine · Neurology

Background Early‐onset Alzheimer's disease (EOAD), manifesting before age 65, demands nuanced diagnostic approaches. FDG18‐PET unveils metabolic insights, the MRI scale captures structural changes, and ACE‐R assesses cognitive impairment details. A holistic evaluation enhances diagnostic precision and enriches our understanding of cognitive decline...

Background Early‐onset Alzheimer’s disease (EOAD), distinct from late‐onset cases, tends to present with atypical cognitive decline, such as, progressive aphasia, apraxia, visuospatial and comportmental impairments,. This study aims to investigate correlations between clinical presentation and PET imaging findings in EOAD patients. Method A retros...

Background Early‐onset Alzheimer's disease (EOAD), manifesting before age 65, demands nuanced diagnostic approaches. FDG18‐PET unveils metabolic insights, the MRI scale captures structural changes, and ACE‐R assesses cognitive impairment details. A holistic evaluation enhances diagnostic precision and enriches our understanding of cognitive decline...

Background Patients with mild cognitive impairment due to Alzheimer’s disease (ADMCI) are characterized by abnormalities in resting‐state electroencephalographic (rsEEG) rhythms as measures of brain neural synchronization dysfunction (Babiloni et al., PMID: 33860614). Here, we tested the two following hypotheses that those rsEEG abnormalities: (i)...

Background Mild cognitive impairment (MCI) is viewed as a transitional stage between normal aging and Alzheimer's disease (AD), serving as a pathological precursor to AD. Longitudinal studies indicate an annual conversion rate from MCI to AD of 10‐15%. Our previous studies have shown decreased coherence values in visual event‐related slow frequency...

Background Early‐onset Alzheimer’s disease (EOAD), distinct from late‐onset cases, tends to present with atypical cognitive decline, such as, progressive aphasia, apraxia, visuospatial and comportmental impairments,. This study aims to investigate correlations between clinical presentation and PET imaging findings in EOAD patients. Method A retros...

Background Vigilance and sleep disturbances in Alzheimer’s and related diseases, even at the stage of mild cognitive impairment (MCI), have been extensively documented, showing abnormal daytime naps and alterations in the sleep‐wake cycle. However, the EEG correlates of the transition from wakefulness to light sleep have not yet been compared betwe...

Background The amplitude of resting‐state electroencephalographic (rsEEG) rhythms is a promising neurophysiological biomarker to investigate the abnormalities of oscillatory neurophysiological thalamocortical mechanisms related to the general cortical arousal and vigilance in wakefulness in patients with dementia due to neurodegenerative diseases a...

Background Huntington’s disease (HD) is a progressive neurodegenerative disorder phenotypically manifested by motor, cognitive and psychiatric symptoms (Novak and Tabrizi, 2011). These patients are also characterized by vigilance abnormalities. This has been demonstrated by electrophysiological measures (Wiegand et al., 1991). In particular, previo...

Background Parkinson’s disease and Huntington’s disease are both neurodegenerative conditions involving the basal ganglia area of the brain. Both conditions can cause symptoms that affect movement. Cognitive decline or dementia can also occur in both. Resting state EEG (rsEEG) rhythms reflect neurophysiological mechanisms and operational functions...

Patients with mild cognitive impairment due to Alzheimer’s disease (ADMCI) typically show abnormally high delta (<4 Hz) and low alpha (8–12 Hz) rhythms measured from resting-state eyes-closed electroencephalographic (rsEEG) activity. Here, we hypothesized that the abnormalities in rsEEG activity may be greater in ADMCI patients than in those with M...

Functional networks representing human brain dynamics have become a standard tool in neuroscience, providing an accessible way of depicting the computation performed by the brain in healthy and pathological conditions. Yet, these networks share multiple characteristics with those representing other natural and man-made complex systems, leading to t...

The present study was developed based on the data of The PDWAVES Consortium (www.pdwaves.eu) and the PharmaCog project. The Partners and institutional affiliations are reported on the cover page of this manuscript. In this study, the clinical, neuropsychological, and magnetic resonance imaging data collection and analysis in patients with ADMCI and...

Background Biomarkers of Alzheimer’s disease (AD) and mild cognitive impairment (MCI, or prodromal AD) are highly significant for early diagnosis, clinical trials and treatment outcome evaluations. Electroencephalography (EEG), being noninvasive and easily accessible, has recently been the center of focus. However, a comprehensive understanding of...

Background Structural income inequality – the uneven income distribution across regions or countries – could affect brain structure and function, beyond individual differences. However, the impact of structural income inequality on the brain dynamics and the roles of demographics and cognition in these associations remains unexplored. Methods Here...

Many coronavirus disease 2019 (COVID‐19) positive individuals exhibit abnormal electroencephalographic (EEG) activity reflecting “brain fog” and mild cognitive impairments even months after the acute phase of infection. Resting‐state EEG abnormalities include EEG slowing (reduced alpha rhythm; increased slow waves) and epileptiform activity. An exp...

Brain clocks, which quantify discrepancies between brain age and chronological age, hold promise for understanding brain health and disease. However, the impact of diversity (including geographical, socioeconomic, sociodemographic, sex and neurodegeneration) on the brain-age gap is unknown. We analyzed datasets from 5,306 participants across 15 cou...

Background/aim: In this study, besides the evaluation of gray and white matter changes in cognitively normal Parkinson's disease (PD-CN) patients with volumetric magnetic resonance imaging (MRI) parameters, it was tried to show that some neuropsychological tests may be impaired in PD-CN patients. Materials and methods: Twenty-six PD-CN patients...

Neurodegenerative diseases such as Parkinson's (PD) and Alzheimer's (AD) exhibit considerable heterogeneity of functional brain features within patient populations, complicating diagnosis, treatment, prognosis, and drug discovery. Here, we use electroencephalography (EEG) and normative modeling to investigate neurophysiological oscillatory mechanis...

Background/aim Amnestic mild cognitive impairment (aMCI) is a risk factor for dementia, and thus, it is of interest to enlighten specific brain atrophy patterns in aMCI patients. We aim to define the longitudinal atrophy pattern in subcortical structures and its effect on cognition in patients with aMCI. Materials and methods Twenty patients with...

Earlier research has suggested gender differences in event-related potentials/oscillations (ERPs/EROs). Yet, the alteration in event-related oscillations (EROs) in the delta and theta frequency bands have not been explored between genders across the three age groups of adulthood, i.e., 18–50, 51–65, and >65 years. Data from 155 healthy elderly part...

Objective The objective of this study was to investigate the functional changes associated with mild cognitive impairment (MCI) using independent component analysis (ICA) with the word generation task functional magnetic resonance imaging (fMRI) and resting‐state fMRI. Methods In this study 17 patients with MCI and age and education‐matched 17 hea...

Abnormal reward processing and psychomotor slowing are well-known in schizophrenia (SZ). As a slow frontocentral potential, contingent negative variation (CNV) is associated with anticipatory attention, motivation and motor planning. The present study aims to evaluate the early and late amplitude and latencies of CNV in patients with SZ compared to...

The present exploratory study tested the hypothesis that computerized cognitive training (CCT) in home telemonitoring may beneficially affect eyes-closed resting-state electroencephalographic (rsEEG) rhythms in Parkinson's disease patients with cognitive deficits (PDCD). A Eurasian database provided clinical-demographic-rsEEG datasets in 40 PDCD pa...

Brain clocks, which quantify discrepancies between brain age and chronological age, hold promise for understanding brain health and disease. However, the impact of multimodal diversity (geographical, socioeconomic, sociodemographic, sex, neurodegeneration) on the brain age gap (BAG) is unknown. Here, we analyzed datasets from 5,306 participants acr...

INTRODUCTION Alzheimer's disease (AD) and behavioral variant frontotemporal dementia (bvFTD) lack mechanistic biophysical modeling in diverse, underrepresented populations. Electroencephalography (EEG) is a high temporal resolution, cost‐effective technique for studying dementia globally, but lacks mechanistic models and produces non‐replicable res...

Background Among the other frequencies, the gamma frequency has received the least attention in the study of Alzheimer’s disease (AD). Previous studies point to association between amyloid accumulation and gamma alterations, suggesting that gamma activity may serve as a potential biomarker for the pathophysiology of AD. The goal of the current stud...

Background Previous studies have shown that patients with Mild Cognitive Impairment due to Alzheimer’s disease (ADMCI) were characterized by reduced posterior rsEEG alpha rhythms after a 12‐month follow‐up (Babiloni et al., 2013). However, none of them have found an alpha deterioration considering a shorter follow‐up. A promising neurophysiological...

Background Abnormalities in cortical sources of resting‐state eyes closed electroencephalographic (rsEEG) rhythms recorded by hospital settings (10‐20 montage) with 19 scalp electrodes characterized Alzheimer’s disease (AD) from preclinical to dementia stages. An intriguing rsEEG application is the monitoring and evaluating of AD progression in lar...

Background Although recent studies showed that gamma frequency entrainment might have therapeutic effects on Alzheimer’s Disease (AD) (Iaccarino et al. 2016), the gamma band abnormalities in AD patients are still poorly understood, while some studies presented increased gamma responses in AD, others showed reduced gamma responses (Güntekin et al.,...

Background Patients with dementia due to Alzheimer’s disease (ADD) and Parkinson’s disease (PDD) suffer from vigilance dysregulation. We hypothesized that such dysregulation may be reflected by altered reactivity of posterior resting‐state electroencephalographic (rsEEG) alpha rhythms during the vigilance transition from eyes‐closed to ‐open condit...

Background and Objectives: The pathophysiology of mild cognitive impairment in Parkinson’s disease (PD-MCI) is still not fully elucidated. It has been shown in a few studies in the literature that volume loss in the occipital, parietal and frontal cortices and atrophy in the hippocampus of PD-MCI patients can occur in the early stages of PD. The ai...

Introduction: Pre-symptomatic screening is getting more attention in healthcare as it detects the risk for developing neurodegenerative diseases like Alzheimer’s disease (AD), which is very useful for treatment or prevention. AD screening could play an important role in individuals with at least one affected first-degree relative, but also without...

It is well known that abnormal reward processing is a characteristic feature of various psychopathologies including schizophrenia (SZ). Reduced reward anticipation has been suggested as a core symptom of SZ. The present study aims to evaluate the event-related oscillations (EROs) delta, theta, alpha, beta, and gamma in patients with SZ during the M...

We propose a novel approach for the reconstruction of functional networks representing brain dynamics based on the idea that the coparticipation of two brain regions in a common cognitive task should result in a drop in their identifiability, or in the uniqueness of their dynamics. This identifiability is estimated through the score obtained by dee...

Here, we discuss relevant literature findings on abnormal resting-state scalp-recorded electroencephalographic (rsEEG) rhythms in old patients with severe cognitive deficits and disabilities in activities of daily living (i.e., dementia) due to Alzheimer’s (ADD), Parkinson’s (PDD), and Lewy body (DLB) neurodegenerative diseases. Furthermore, we des...

Alterations in P300 amplitude and latency, as well as neuropsychological tests, are informative to detect early signs of the affected high cognitive processing in Mild Cognitive Impairment (MCI). In the present study, we examined P300 latency and amplitude elicited by visual oddball paradigm in 20 participants with MCI and age, education, and sex-m...

Here we tested the hypothesis of a relationship between the cortical default mode network (DMN) structural integrity and the resting-state electroencephalographic (rsEEG) rhythms in patients with Alzheimer’s disease with dementia (ADD). Clinical and instrumental datasets in 45 ADD patients and 40 normal elderly (Nold) persons originated from the PD...

It is well known that abnormal reward processing is a characteristic feature of various psychopathologies including schizophrenia. Reduced reward anticipation has been suggested as a core symptom of schizophrenia. The Monetary Incentive Delay Task (MID) is frequently used to detect reward anticipation. The present study aims to evaluate the amplitu...

Background Amnestic mild cognitive impairment (aMCI) is a transitional state between normal aging and dementia, and identifying early biomarkers is crucial for disease detection and intervention. Functional magnetic resonance imaging (fMRI) has the potential to identify changes in neural activity in MCI. Methods We investigated neural activity cha...

Objective: This study investigated cortical thickness differences and their relationships with cognitive functions in Parkinson's disease (PD) with mild cognitive impairment (MCI) and cognitively normal (CN). Materials and Methods: Twenty-two patients with PD-MCI, 23 with PD-CN, and 23 healthy controls with structural brain magnetic resonance imagi...

Background Abnormalities in the neurophysiological oscillatory mechanisms generating dominant resting‐state eyes closed electroencephalographic (rsEEG) rhythms portray the Alzheimer’s disease (AD) continuum, from the preclinical to the dementia stage. Here, we tested whether these abnormalities may be reproducible by analyzing the rsEEG signals acq...

Background The resting state eyes‐closed electroencephalographic (rsEEG) alpha (8‐12 Hz) rhythms reflect cortical neural synchronization mechanisms underpinning the inhibition of sensory, cognitive, and motor areas in parietal, temporal, and occipital cortex during a condition of low vigilance. Here we tested the hypothesis that age may diversely a...

Background Graph theory models a network by its nodes and connections. “Degree” hubs reflect node centrality, while “connector” hubs are those linked to several clusters of nodes. Here we compared hubs modelled from measures of interdependencies of between‐electrode resting‐state eyes‐closed electroencephalography (rsEEG) rhythms in normal old (Nol...

Background Event‐related oscillations (EROs) during cognitive paradigms reflect several cognitive functions in the brain. Event‐related delta responses are related to signal detection and decision making processes whereas theta is associated with working memory and selective attention (Yener and Başar, 2013; Başar et al., 2016). During physiologica...

Background Apneas occur more than 30 times per hour in severe obstructive sleep apnea syndrome (OSAS) patients. Each apnea results in decrease of oxygen saturation that leads to recurring intermittent hypoxemia (IH). IH was suggested as a possible factor to contribute cognitive impairment in OSAS. In the present study, we aimed to investigate the f...

Purpose: People with Parkinson's disease (PD) can develop cognitive and physical impairments. There is limited evidence on the association between executive function and physical function in people with PD. Objective: We aimed to investigate the association between the executive and physical functions in people with Parkinson's disease (PD) by c...

Introduction: Graph theory models a network by its nodes (the fundamental unit by which graphs are formed) and connections. 'Degree' hubs reflect node centrality (the connection rate), while 'connector' hubs are those linked to several clusters of nodes (mainly long-range connections). Methods: Here, we compared hubs modeled from measures of int...

Demans tarama ve tanısı için klinik pratikte sıklıkla kısa tarama testleri kullanılmaktadır. Mini Mental Durum Testi (MMDT) en sık kullanılan testlerin başında gelmektedir. MMDT’nin demans için duyarlı olduğu bilinmektedir. Ancak, sağlıklı yaşlanma ile demans arasında bir geçiş evresi olarak kabul edilen Hafif Kognitif Bozukluk (HKB)’un ayırt edilm...

Background: The effectiveness of telehealth applications for family caregivers of individuals with dementia remains unclear. The aim of this study is to investigate how telehealth-based interventions applied for family caregivers of individuals with dementia affect their self-efficacy levels, caregiving burden, stress, depression, and quality of l...

Successful use of sensory 40 Hz‐gamma entrainment has been shown in Alzheimer’s Disease animal models. Few studies had used 40 Hz‐gamma sensory gamma entrainment on human subjects and there are contradictory results on these studies. We think there could be different frequency dynamics in animals and in humans. To answer this question, we aimed to...

Purpose: To compare white matter (WM) structural alterations between the subjects with amnestic mild cognitive impairment (MCI) which is a transitional state to Alzheimer's Disease (AD) and healthy elderly controls. Methods: Diffusion tensor imaging (DTI) scans of 20 subjects with amnestic MCI and 20 healthy control groups who are matched by age, g...

Objectives Working memory performances are based on brain functional connectivity, so that connectivity may be deranged in individuals with mild cognitive impairment (MCI) and patients with dementia due to Alzheimer’s disease (ADD). Here we tested the hypothesis of abnormal functional connectivity as revealed by the imaginary part of coherency (ICo...

Abnormalities in cortical sources of resting-state eyes closed electroencephalographic (rsEEG) rhythms recorded by hospital settings (10-20 montage) with 19 scalp electrodes characterized Alzheimer's disease (AD) from preclinical to dementia stages. An intriguing rsEEG application is the monitoring and evaluation of AD progression in large populati...

Alzheimer’s disease (AD) is a neurodegenerative brain disease affecting cognitive and physical functioning. The currently available pharmacological treatments for AD mainly contain cholinesterase inhibitors (AChE-I) and N-methyl-d-aspartic acid (NMDA) receptor antagonists (i.e., memantine). Because brain signals have complex nonlinear dynamics, the...

Objectives The aim of this study was to differentiate individuals with early-onset Alzheimer's disease (EOAD) and identify differences of functional connectivity in resting-state EEG between individuals with EOAD and late-onset AD (LOAD) in comparison with both healthy young and elderly individuals. Methods Forty EOAD and 56 LOAD patients were inc...

Many structural and functional tests are used to explore the nature of neurodevelopmental and neurodegenerative diseases. Cognitive involvement has become more and more remarkable in many neurological and psychiatric diseases. This condition evoked a paradigm shift, and today disorders are addressed from a neuroscientific perspective, including sil...

Parkinson's disease (PD) is a multifaceted neurodegenerative disorder accompanied by mild cognitive impairment (MCI) as a crucial non-motor manifestation. Event-related oscillations (EROs) are suggested to reflect cognitive status associated with subcortical structures in neurodegenerative conditions. In this study, thirty-six individuals with PD-M...

Abnormalities in cortical sources of resting-state eyes-closed electroencephalographic (rsEEG) rhythms recorded by hospital settings (10–20 electrode montage) with 19 scalp electrodes provide useful markers of neurophysiological dysfunctions in the vigilance regulation in patients with Alzheimer's disease dementia (ADD). Here we tested whether thes...

Unlabelled: Alzheimer's disease (AD) is an important brain disease associated with aging. It involves various functional and structural changes which alter the EEG characteristics. Although numerous studies have found changes in delta, theta, alpha, and beta power, fewer studies have looked at the changes in the resting state EEG gamma activity ch...

Parkinson's disease (PD) is a movement disorder caused by degeneration in dopaminergic neurons. During the disease course, most of PD patients develop mild cognitive impairment (PDMCI) and dementia, especially affecting frontal executive functions. In this study, we tested the hypothesis that PDMCI patients may be characterized by abnormal neurophy...