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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 Shrinkage of olfactory amygdala connotes cognitive impairment in patients with Parkinson’s disease(Springer, 2023-10) Ay, Ulaş; Yıldırım, Zerrin; Erdoğdu, Emel; Kıçik, Ani; Öztürk Işık, Esin; Demiralp, Tamer; Gürvit, HakanDuring the caudo-rostral progression of Lewy pathology, the amygdala is involved relatively early in Parkinson’s disease (PD). However, lesser is known about the volumetric differences at the amygdala subdivisions, although the evidence mainly implicates the olfactory amygdala. We aimed to investigate the volumetric differences between the amygdala’s nuclear and sectoral subdivisions in the PD cognitive impairment continuum compared to healthy controls (HC). The volumes of nine nuclei of the amygdala were estimated with FreeSurfer (nuclear parcellation-NP) from T1-weighted images of PD patients with normal cognition (PD-CN), PD with mild cognitive impairment (PD-MCI), PD with dementia (PD-D), and HC. The appropriate nuclei were then merged to obtain three sectors of the amygdala (sectoral parcellation-SP). The nuclear and sectoral volumes were compared among the four groups and between the hyposmic and normosmic PD patients. There was a significant difference in the total amygdala volume among the four groups. In terms of nuclei, the bilateral cortico-amygdaloid transition area (CAT) and sectors superficial cortex-like region (sCLR) volumes of PD-MCI and PD-D were less than those of the PD-CN and HC. A linear discriminant analysis revealed that left CAT and left sCLR volumes classified the PD-CN and cognitively impaired PD (PD-CI: PD-MCI plus PD-D) with 90.7% accuracy according to NP and 85.2% accuracy to SP. Similarly, left CAT and sCLR volumes correctly identified the hyposmic and normosmic PD with 64.8% and 61.1% accuracies. Notably, the left olfactory amygdala volume successfully discriminated cognitive impairment in PD and could be used as neuroimaging-based support for PD-CI diagnosis.Yayın Posterior atrophy is a neuroimaging marker of mild cognitive impairment in Parkinson's disease(Türk Nöropsikiyatri Derneği, 2026-02-02) Ay, Ulaş; Yıldırım, Zerrin; Kıcik, Ani; Erdoğdu, Emel; Bilgiç, Başar; Hanağası, Haşmet; Öztürk Işık, Esin; Demiralp, Tamer; Gürvit, HakanIntroduction: Although there are several studies on the neuroanatomical mechanisms underlying Parkinson's disease (PD)-associated cognitive impairment, the clinical usefulness of the findings from these investigations is limited. In this study, we aimed to identify magnetic resonance imaging (MRI) markers that can be practically utilized for diagnosing PD-associated cognitive impairment using a visual rating scale (VRS). Methods: Anatomical MRIs of cognitively normal (PD-CN), and PD with mild cognitive impairment (PD-MCI) patients were visually evaluated for six bilateral cortical regions. Then, hypothesis-driven cortical thickness analysis (CTA) was performed in the regions obtained from VRS. Results: As a consequence of VRS, a significant difference was found between the two groups with regards to right posterior atrophy (PA) scores (pFDR-corr = 0.042, Cohen's d= 1.06). Hypothesis-driven CTA confirmed the result of VRS by revealing cortical thinning at the precuneus and parieto-occipital sulcus junction (Max. T= 6.171, P= 0.0006, MNIx, y,z = 11.0,-62.2, 25.4). The area under the curve was 0.75, showing a good association between the PD-MCI and the right PA score. The cut-off for maximum accuracy was >= 2, based on the highest sum of sensitivity (0.68) and specificity (0.72). Conclusions: Our findings indicate that right PA atrophy may be helpful for clinicians in the diagnosis of PD-associated cognitive impairment.
