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Yayın Detection of visual and frontoparietal network perfusion deficits in Parkinson's disease dementia(Elsevier Ireland Ltd, 2021-11) Azamat, Sena; Arslan, Dilek Betül; Erdoğdu, Emel; Kıçik, Ani; Cengiz, Sevim; Eryürek, Kardelen; Tüfekçioğlu, Zeynep; Bilgiç, Başar; Hanagasi, Haşmet; Demiralp, Tamer; Gürvit, Hakan; Öztürk Işık, EsinMild cognitive impairment of Parkinson's disease (PD) may be an early manifestation that may progressively worsen to dementia. Cognitive decline has been associated with changes in the brain perfusion pattern. This study aimed to evaluate cerebral blood flow (CBF) deficits specific to different stages of cognitive decline. Seventeen patients with cognitively normal PD (PD-CN), 18 patients with PD with mild cognitive impairment (PD-MCI), and 16 patients with PD with dementia (PDD) were included in this study. The participants were scanned using a 3 T Philips MRI scanner. Arterial spin labelling magnetic resonance (ASL-MR) images were acquired, followed by calculation of the CBF maps, and registration onto the MNI152 brain atlas. A whole-brain voxel-based CBF comparison was performed among the patient groups using age as a covariate. The mean age of patients with PDD was significantly higher than that of patients with PD-MCI (P = 0.015) and PD-CN (P = 0.001). The CBF values of the three groups were significantly different in the left cuneus of the visual network (VN), left inferior frontal gyrus of the frontoparietal network (FPN), and left dorsomedial nucleus of the thalamus. PDD had lower perfusion values than PD-MCI group in the same regions detected in the main group analysis. Additionally, comparison of PDD with PD-CN and non-demented groups revealed that the perfusion reduction extended into the bilateral cuneus of the VN, bilateral thalami, and left inferior frontal gyrus of the FPN. PDD could be separated from PD-MCI and PD-CN stages with CBF deficits in non-dopaminergically mediated posterior and dopaminergically mediated frontal networks.Yayın Corrigendum to “Detection of visual and frontoparietal network perfusion deficits in Parkinson’s disease dementia” [Eur. J. Radiol. 144 (2021) 109985](Elsevier Ireland Ltd, 2022-10-28) Azamat, Sena; Arslan, Dilek Betül; Erdoğdu, Emel; Kıçik, Ani; Cengiz, Sevim; Eryürek, Kardelen; Tüfekçioğlu, Zeynep; Bilgiç, Başar; Hanagasi, Haşmet; Demiralp, Tamer; Gürvit, Hakan; Öztürk Işık, EsinThe authors would like to add the following grant support that was accidentally not included in the original article. Acknowledgements: This study was supported by TUBITAK 1001 project #115S219, Istanbul University Scientific Research Projects Unit project #1567/42362 and Bogazici University Scientific Research Projects Unit project #15222. The authors would like to apologize for any inconvenience caused.Yayın Investigation of symptom-specific functional connectivity patterns in Parkinson’s disease(Springer-Verlag Italia S.R.L., 2025-06-14) Kıçik, Ani; Bayram, Ali; Erdoğdu, Emel; Kurt, Elif; Sarıdede, Dilek Betül; Cengiz, Sevim; Bilgiç, Başar; Hanağası, Haşmet; Öztürk Işık, Esin; Gürvit, Hakan; Tüzün, Erdem; Demiralp, TamerParkinson’s disease (PD) is a complex neurodegenerative disease, characterized by pronounced heterogeneity in symptoms. This study investigates the functional connectivity (FC) patterns associated with distinct symptom clusters, aiming to elucidate the heterogeneity in PD and uncover the neural mechanisms underlying its motor and cognitive symptoms. Resting-state functional MRI (rs-fMRI) data from 55 non-demented PD patients and 24 healthy controls (HC) were used to perform seed-to-seed FC analyses. A clustering algorithm was applied to the cognitive and motor scores of all PD patients to generate relatively homogeneous symptomatic subgroups. PD patients exhibited a general decrease in FC within a network comprising the sensorimotor network (SMN) and the visual network (VN) regions. Symptom-based clustering revealed three relatively homogeneous subgroups, exhibiting a gradient pattern: patients with greater motor deficits showed significant disconnection within the SMN, whereas patients with greater visuospatial deficits exhibited reduced FC in an extended subnetwork, with pronounced disconnections between the VN and SMN areas. Our study demonstrated a notable disconnection between the SMN and VN, indicating impaired visual-motor integration in PD. Stronger disconnection within the SMN was associated with greater motor dysfunction, and stronger visual-sensorimotor disconnections were associated with greater visuospatial deficits. These findings suggest that at least two separate routes of functional disconnection may be responsible for the inhomogeneous symptom distribution in PD.Yayın Reliability of direct-to-home teleneuropsychological assessment: a within-subject design study(Routledge, 2025-07-04) Yıldırım, Elif; Soncu Büyükişcan, Ezgi; Akça Kalem, Şükriye; Gürvit, HakanObjective: During the COVID-19 pandemic, the need to continue diagnosis and treatment processes, in addition to scientific research, led to a rapid shift towards direct-to-home tele-neuropsychology administrations, the reliability and validity of which had not been clearly established then. This study, therefore, aimed to examine the reliability of direct-to-home tele-neuropsychological assessment (TNP). Method: The sample included 105 cognitively healthy individuals aged between 50–83 years, and 47 patients diagnosed with neurocognitive disorders (mild cognitive impairment and early-stage Alzheimer’s type dementia). All participants underwent both face-to-face and teleneuropsychological assessments in a counterbalanced order. Results: The results revealed that performances across measures of attention, working memory, verbal fluency, verbal and visual memory, and visual perception were comparable across assessment modalities. Intraclass correlation coefficients of the tests ranged from.54 to.92. Conclusions: The findings of the study provide support for direct-to-home teleneuropsychological assessment among patients with neurocognitive disorders. Neuropsychological tests relying on verbal administration and independent of motor performance may represent a reliable alternative for this patient group when administered in settings where external distractions or technological limitations are controlled. For cognitively healthy individuals, on the other hand, the reliability of the TNP application is more questionable for memory and some executive function tests and therefore needs further exploration.
