Browsing by Author "Öz, Didem"

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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.
Citation - WoS: 2
Citation - Scopus: 4
Innovations in Neurophysiology and Their Use in Neuropsychiatry
(Turkish Neuropsychiatry Assoc-Turk Noropsikiyatri Dernegi, 2022) Yener, Görsev; Öz, Didem
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 disorders. This condition evoked a paradigm shift, and today disorders are addressed from a neuroscientific perspective, including silent symptoms. The spatial resolution of structural studies is lacking and is combined with the unique temporal resolution of EEG methods. In our current clinical practice, EEG does not have definitive diagnostic value in psychiatric disorders, but it helps to make a correct diagnosis by excluding other neurological diseases. However, the use of EEG for research purposes is promising in both groups. In this review; there is up-to-date information on the use of electrophysiological examinations in neurological diseases, especially Alzheimer's disease, Parkinson's disease, Frontotemporal dementia, and psychiatric disorders such as schizophrenia, mood disorders, attention deficit and hyperactivity disorder, and obsessive-compulsive disorder, to define the point we have reached in our journey to understand these disorders.
Citation - WoS: 7
Citation - Scopus: 8
Normalized Theta but Increased Gamma Activity After Acetylcholinesterase Inhibitor Treatment in Alzheimer's Disease: Preliminary Qeeg Study
(Sage Publications Inc, 2023) Fide, Ezgi; Yerlikaya, Deniz; Öz, Didem; Öztura, İbrahim; Yener, Görsev
Acetylcholinesterase inhibitors (AChE-I) are the core treatment of mild to severe Alzheimer's disease (AD). However, the efficacy of AChE-I treatment on electroencephalography (EEG) and cognition remains unclear. We aimed to investigate the EEG power and coherence changes, in addition to neuropsychological performance, following a one-year treatment. Nine de-novo AD patients and demographically-matched healthy controls (HC) were included. After baseline assessments, all AD participants started cholinergic therapy. We found that baseline and follow-up gamma power analyzes were similar between groups. Yet, within the AD group after AChE-I intake, individuals with AD displayed higher gamma power compared to their baselines (P < .039). Also, baseline gamma coherence analysis showed lower values in the AD than in HC (P < .048), while these differences disappeared with increased gamma values of AD patients at the follow-up. Within the AD group after AChE-I intake, individuals with AD displayed higher theta and alpha coherence compared to their baselines (all, P < .039). These increased results within the AD group may result from a subclinical epileptiform activity. Even though AChE-I is associated with lower mortality, our results showed a significant effect on EEG power yet can increase the subclinical epileptiform activity. It is essential to be conscious of the seizure risk that treatment may cause.