İşbitiren, Yağmur Özbek
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Özbek, Yagmur
Ozbek, Yagmur
Ozbek-Isbitiren, Yagmur
Oezbek, Yagmur
Isbitiren, Yagmur Ozbek
Ozbek, Yagmur
Ozbek-Isbitiren, Yagmur
Oezbek, Yagmur
Isbitiren, Yagmur Ozbek
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yagmur.ozbek@ieu.edu.tr
Main Affiliation
09.03. Medicine
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Current Staff
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Sustainable Development Goals
SDG data is not available
Documents
11
Citations
237
h-index
7
Documents
19
Citations
259
Scholarly Output
12
Articles
11
Views / Downloads
13/28
Supervised MSc Theses
0
Supervised PhD Theses
0
WoS Citation Count
164
Scopus Citation Count
38
WoS h-index
5
Scopus h-index
3
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0
Projects
0
WoS Citations per Publication
13.67
Scopus Citations per Publication
3.17
Open Access Source
5
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0
| Journal | Count |
|---|---|
| Alzheimers & Dementia | 1 |
| Clınıcal Neurophysıology | 1 |
| Computer Methods And Programs in Bıomedıcıne | 1 |
| Cukurova Medıcal Journal | 1 |
| Internatıonal Journal of Psychophysıology | 1 |
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12 results
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Now showing 1 - 10 of 12
Article Clinical Manifestations(2025) Tee, Boon Lead; Sung, Jee Eun; Cappa, Stefano F.; Carlesimo, G.; Öz, Didem; Özbek, Y.; Tempini, M.L.G.BACKGROUND: The digit span task, a measure of auditory verbal short-term and working memory, is widely used globally. Emerging research has revealed variations in digit span performance across languages among young adults; however, studies focusing on older populations are scarce and typically involving limited languages. This study investigates digit span performance among older adults (40-90 year-old) across fourteen languages and explored the influence of lexical and numerical properties on cognitive assessment. METHOD: We examined digit span performance among cognitively normal participants (CN), individuals with mild cognitive impairment (MCI) and Alzheimer's disease (AD) across fourteen language cohorts totalling 3,681 participants: English (n = 446), Mandarin (n = 97), Cantonese (n = 65), Spanish (n = 218), Kannada (n = 69), Hindi (n = 72), Telugu (n = 69), Malayalam (n = 70), Bengali (n = 70), French (n = 299), Korean (n = 1098), Italian (n = 540), Arabic (n = 50), and Turkish (n = 518). First, we analyzed language differences in digit span performance among CN using ANOVA and general linear models. We then conducted Receiver operating characteristic (ROC) analyses to identify the optimal cutoff values for AD. Next, we computed the digit count, syllable count, and numerical magnitude (i.e. the average sum of the digits) of all digit stimuli in the English cohort and analyzed their effects via linear and ridge regression analyses. RESULT: The forward (FDS) and backward digit span (BDS) tests revealed significant differences among CN across the fourteen language cohorts even after adjusting for age and education (FDS:F=38.62, p <0.001; BDS:F=19.23, p <0.001). ROC analysis revealed varying optimal cutoff values across languages: English (FDS:6, BDS:4), Italian and Turkish (FDS:5, BDS:4), Mandarin (FDS:7, BDS:5), Cantonese (FDS:7, BDS:4), and French (FDS:6, BDS:3). Further analysis indicated that the interaction between digit and syllable counts significantly impacted FDS accuracy in English speakers (linear:p=0.00035; ridge:p< 0.000001), with no significant effect from digit count alone after adjusting for interaction. Conversely, BDS performance showed a significant negative influence from digit count (p = 0.00858), with numerical magnitude and syllable count nearing significance (p = 0.083 and p = 0.066, respectively). CONCLUSION: Variations in digit span performance across languages illustrate the role of linguistic and numerical factors in cognitive assessments, even with tests targeting non-language domains using digit stimuli. These findings underscore the critical value of language diversity in cognitive research. © 2025 The Alzheimer's Association. Alzheimer's & Dementia published by Wiley Periodicals LLC on behalf of Alzheimer's Association.Article Citation - WoS: 2Citation - Scopus: 2Cognitive Evidence on Eeg-P300 in Healthy Individuals With High Depression Scores(Wolters Kluwer Medknow Publications, 2022) Oz, Didem; Ozbek, Yagmur; Kiyi, Ilayda; Ozturk, Bilge Targitay; Oztura, Ibrahim; Yener, GörsevBackground:Depression is common among elderly and middle-aged individuals and is a reason for decreased quality of life. Depression may lead to impairments in cognitive abilities. The P300 potential is one of the most used event-related potentials (ERPs) to evaluate cognition. This study investigated the P300 amplitude differences between individuals with depressive symptoms and nondepressed healthy elderly individuals. Materials and Methods:The current study included twenty individuals with high depression scores (high DS, age: 64.80 +/- 7.22, 6 M/14 F) and twenty demographically matched participants with low depression scores (low DS, age: 64.20 +/- 6.21, 7 M/13 F). The Geriatric Depression Scale (GDS) was used to evaluate whether participants have depressive symptoms. All of the participants were underwent a comprehensive neuropsychological battery. The ERPs were recorded with a visual classical oddball paradigm. The P300 amplitudes were measured in the 250-550 ms time window. Results:High DS group had lower P300 amplitudes than low DS individuals regardless of electrode location. Correlation analyses showed that there was a significant correlation between GDS scores and the P300 amplitudes recorded from the F-z electrode. Conclusion:The current study showed the reduced P300 amplitudes on individuals with high GDS scores. The P300 potential may be a useful tool to determine possible changes or impairments due to subthreshold depressive symptoms.Article Citation - WoS: 10Citation - Scopus: 11The Reliability of P300 and the Influence of Age, Gender and Education Variables in a 50 Years and Older Normative Sample(Elsevier, 2022) Yerlikaya, Deniz; Hunerli-Günduz, Duygu; Fide, Ezgi; Özbek, Yağmur; Kıyı, İlayda; Öztura, İbrahim; Yener, GörsevObjectives: The present study aims to investigate the effects of age, gender, and level of education on P300 in a healthy population, aged 50 years and over; and determine the reliability metrics for different conditions and measurement methods.Method: Auditory and visual oddball recordings of 171 healthy adults were investigated. A fully automated preprocessing was applied to elicit ERP P300. Maximum peak amplitude, latency and mean amplitudes were measured. Data were stratified by age, gender, and education to determine group-level differences by using repeat measures of ANOVA. The internal consistency of P300 was calculated by a split-half method using odd-even segments. Test-retest reliability was assessed by calculating the intraclass correlation coefficient (ICC).Results: Maximum peak P300 amplitudes were higher in the 50-64 years age group compared to the >65 years age group; and females showed increased P300 amplitudes compared to males. P300 measures showed fair to good internal consistency and poor to good test-retest reliability.Conclusion: Age and gender should be taken into account when designing ERP studies with elderly individuals. P300 showed good internal consistency in general, between gender groups and age groups. Long-term test-retest reliability was lower but acceptable. These findings can be interpreted as the strength of P300 by being an objective and reliable method independent of cultural differences. Here we underline several factors that may affect P300 measures and discuss other possible factors that should be standardized for P300 to be used in clinical settings.Review Article Citation - WoS: 2Citation - Scopus: 2Senior Moments Are Never-Ending Times When You Are Old (are They?): First Step of Turquoise Project(Turkish Neuropsychiatry Assoc-Turk Noropsikiyatri Dernegi, 2022) Oz, Didem; Yildirim, Zerrin; Kiyi, Ilayda; Ozbek, Yagmur; Kulac, Ibrahim; Erkol, Gokhan; Tihan, Tarik; Yener, GörsevIntroduction: The number of dementia patients is increasing in Turkey,, as well as all over the world. However, we do not know how much the society knows about dementia. The aim of this study is to evaluate people's concept of dementia, their awareness of dementia research and treatment, whether dementia and forgetfulness are considered normal in old age, and whether having dementia is associated with a lack of mental abilities. Methods: A Dementia Awareness Questionnaire was created in the form of a self-report questionnaire, consisting of 20 questions and using a five-point Likert-type answering method in order to question participants' information about dementia. In addition, we asked for demographic information such as age, gender, occupation, education level of the participants, as well as whether they have had relatives diagnosed with a neurodegenerative disease. The surveys were administered online. Results: A total of 1551 participants from 53 cities were included in the study. Approximately half of the participants did not know the definition of dementia, 20.9% thought that dementia and Alzheimer's disease were the same; 50.4% considered forgetfulness, and 55.2% considered dementia as a natural consequence of aging. While 34.5% of the participants thought that dementia patients could be dangerous, 10.3% thought they could not continue living as a part of society. While 38.5% of healthcare professionals do not know the definition of dementia, 18.5% of them say that dementia and Alzheimer's disease are the same, 58.5% think that dementia patients are not fit to make their own decisions, 40.6% believe that dementia patients have criminal liability. 15.8% of healthcare professionals thought that dementia is only seen in elderly people; 21.4% thought that dementia, and 49.2% thought that forgetfulness was a result of normal aging. Conclusion: Our study confirms that dementia is still an unknown concept in society and among healthcare professionals. It is widely believed that forgetfulness and dementia are part of normal aging, and there is no cure for dementia. This study, which we have done in order to understand the level of dementia awareness in Turkish society, reveals the necessity for research on dementia and studies on how to increase dementia awareness.Article Citation - WoS: 11Citation - Scopus: 10Cross-Cultural Comparison of Mmse and Rudas in German and Turkish Patients With Alzheimer's Disease(Amer Psychological Assoc, 2022) Celik, Simge; Onur, Oezguer; Yener, Görsev; Kessler, Josef; Oezbek, Yagmur; Meyer, Patric; Froelich, LutzObjective: Given the increasing cultural, linguistic diversity in Europe, there is a growing need for cognitive screening tools that minimize the influence of linguistic, cultural, and demographic differences as they are the first means to determine the need for further clinical evaluation of individuals with suspected cognitive impairment. This cross-sectional study compared performance on the Mini-Mental State Examination (MMSE) and the Rowland Universal Dementia Assessment Scale (RUDAS) in Alzheimer's Disease (AD) patients in relation to cultural, demographic, and immigration-related factors (acculturation, bilingualism). Method: The study comprised Turkish immigrant (n = 21) and monolingual, nonimmigrant German (n = 20) and Turkish (n = 24) patients with AD. All participants were administered cognitive screening tools, measures of depression, and dementia severity. Results: The mean MMSE total score was significantly higher in German patients with AD compared to both patient groups, but did not differ between native-born Turkish and Turkish immigrant groups. After adjustment for years of education, differences in MMSE performance were no longer significant between groups. Furthermore, bilingualism was associated with better performance on the MMSE in Turkish-immigrant patients. The mean RUDAS total scores were similar between groups with and without adjustment for educational level. Performance on the RUDAS was not associated with demographic and immigration-related variables. Conclusions: The findings highlight the need to consider the educational background, linguistic integration of older non-Western immigrants for the objective characterization of cognitive profiles. The results provide support for the use of the RUDAS, particularly, among older Turkish immigrants with lower educational levels and varying degrees of acculturation, bilingualism.Article Citation - WoS: 42Resting-State Eeg Alpha/Theta Power Ratio Discriminates Early-Onset Alzheimer's Disease From Healthy Controls(Elsevier Ireland Ltd, 2021) Ozbek, Yagmur; Fide, Ezgi; Yener, GörsevObjectives: The present study aims to compare early-onset Alzheimer's disease (EOAD) patients with healthy controls (HC), and late-onset Alzheimer's disease (LOAD) patients using resting-state delta, theta, alpha, and beta oscillations and provide a cut-off score of alpha/theta ratio to discriminate individuals with EOAD and young HC. Methods: Forty-seven individuals with EOAD, 51 individuals with LOAD, and demographically-matched 49 young and 51 older controls were included in the study. Spectral-power analysis using Fast-Fourier Transformation (FFT) is performed on resting-state electroencephalography (EEG) data. Delta, theta, alpha, and beta oscillations compared between groups and Receiver Operating Characteristic (ROC) curve analysis was conducted. Results: Compared to healthy controls individuals with EOAD showed an increase in slow frequency bands and a decrease in fast frequency bands. Frontal alpha/theta power ratio is the best discriminating value between EOAD and young HC with the sensitivity and specificity greater than 80% with area under the curve (AUC) 0.881. Conclusions: EOAD display more widespread and severe electrophysiological abnormalities than LOAD and HC which may reflect more pronounced pathological burden and cholinergic deficits in EOAD. Additionally, the alpha/theta ratio can discriminate EOAD and young HC successfully. Significance: This study is the first to report that resting-state EEG power can be a promising marker for diagnostic accuracy between EOAD and healthy controls. (C) 2021 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.Article Understanding Effects of Late-Life Depressive Symptoms on Event-Related Oscillations in Cognitively Unimpaired Seniors and Individuals With Mild Cognitive Impairment(Sage Publications inc, 2025) Ozbek, Yagmur; Yener, Gorsev G.Background Late-life depression often co-occurs with neurological disorders such as dementia, significantly impacting cognitive function and overall well-being. Mild cognitive impairment represents a critical stage between normal aging and dementia, often accompanied by depressive symptoms. Electroencephalography (EEG) offers a non-invasive method to investigate underlying neural mechanisms associated with depressive symptoms and cognitive dysfunction.Methods This study included 80 participants categorized into four groups: MCI without depressive symptoms (MCI), MCI with depressive symptoms (MCI-d), cognitively unimpaired individuals without depressive symptoms (CU), and cognitively unimpaired individuals with depressive symptoms (CU-d). Participants underwent neuropsychological evaluations and EEG recordings during a visual oddball paradigm. Event-related oscillations (EROs) in delta, theta, alpha, and beta frequencies were analyzed in frontal, central, parietal, temporal, and occipital electrode locations.Results Delta ERO showed a significant decrease in amplitude in CU-d, MCI, and MCI-d groups compared to CU in frontal, central, and parietal regions. In the temporal area, MCI-d exhibited lower delta amplitudes compared to both CU and CU-d, while MCI showed lower amplitudes compared to CU. No significant differences were observed in theta, alpha, and beta frequencies. Correlation analyses revealed moderate to strong associations between frontal, central, parietal, and temporal delta amplitudes with various neuropsychological test scores, indicating a link between delta oscillations and cognitive function.Discussion Our findings suggest that delta oscillations may serve as potential marker for cognitive dysfunction, particularly in individuals with MCI and depressive symptoms. Notably, lower delta amplitudes were observed in cognitively unimpaired individuals with depressive symptoms compared to those without, underlining the impact of depressive symptoms on cognitive function in healthy elderly individuals. Further studies can bring out that neurophysiological measures may help revealing the effect of depressive symptoms on cognition that was undetected by cognitive testing.Book Part Artificial Intelligence in Clinical Neuroscience(CRC Press, 2025) Ozturk, Seren Duzenli; Hunerli, Duygu; Aykan, Simge; Isbitiren, Yagmur OzbekArtificial Intelligence (AI) is a branch of computer science that focuses on replicating human intelligence in machines (Malik & Solanki, 2021), allowing them to possess problem-solving (Zeigler, Muzy, & Yilmaz, 2009), and decision-making abilities akin to the human brain (Malik & Solanki, 2021). AI methods undergo training using extensive datasets, enabling them to perform specific tasks. Subsequently, they use this acquired knowledge to evaluate unfamiliar data and generate targeted outcomes. One of the remarkable aspects of AI is its capacity to swiftly process massive datasets without human intervention. Advancements in hardware technologies have facilitated a progression from conventional machine learning to deep learning within the field of AI, resulting in the emergence of widely used applications such as natural language processing, speech recognition, computer vision, and image classification parameters (Rana, Rawat, Bijalwan, & Bahuguna, 2018). Moreover, ongoing advancements in hardware aim to move towards neuromorphic hardware, which would lower the energy consumption of AI systems, emulating the energy efficiency of the human brain (Berggren et al., 2020). In essence, AI empowers machines to intelligently and intuitively tackle complex problems and make informed decisions. © 2025 Elsevier B.V., All rights reserved.Article Citation - WoS: 12Citation - Scopus: 12Reduced Power and Phase-Locking Values Were Accompanied by Thalamus, Putamen, and Hippocampus Atrophy in Parkinson?s Disease With Mild Cognitive Impairment: an Event-Related Oscillation Study(Elsevier Science Inc, 2023) Hunerli-Gunduz, Duygu; Isbitiren, Yagmur Ozbek; Uzunlar, Hakan; Cavusoglu, Berrin; Colakoglu, Berril Donmez; Adag, Emel; Yener, GörsevParkinson's disease (PD) is a multifaceted neurodegenerative disorder accompanied by mild cognitive im-pairment (MCI) as a crucial nonmotor manifestation. Event-related oscillations (EROs) are suggested to re-flect cognitive status associated with subcortical structures in neurodegenerative conditions. In this study, 36 individuals with PD-MCI and 32 PD-CN were compared with 60 healthy control (HC) participants us-ing visual EROs by measures of event-related spectral perturbation and inter-trial coherence, along with subcortical gray matter volumes based on the FIRST algorithm. Cross-correlations among electrophysio-logical, neuropsychological, and structural parameters were investigated exploratively. Both PD-MCI and PD-CN patients had diminished delta and alpha phase-locking than HC, however, electrophysiological ab-normalities were more pronounced in PD-MCI over frontal, central, parietal, and temporal locations in almost all frequency bands, accompanied by bilateral thalamus, hippocampus, and right putamen atro-phy. PD-CN had lower hippocampal volumes than HC, without exhibiting any subcortical differences from PD-MCI. Lastly, EROs showed low-to-high correlations with structural and neuropsychological measures. These findings may highlight the complex interplay between electrophysiological, neuropsychological, and structural parameters in detected abnormalities of PD-CN and PD-MCI. (c) 2022 Elsevier Inc. All rights reserved.Article Citation - WoS: 85Complexity of Eeg Dynamics for Early Diagnosis of Alzheimer's Disease Using Permutation Entropy Neuromarker(Elsevier Ireland Ltd, 2021) Seker, Mesut; Özbek, Yağmur; Yener, Görsev; Ozerdem, Mehmet SiracBackground 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. (c) 2021 Elsevier B.V. All rights reserved.
