Retinal Biomarkers in Mild Cognitive Impairment and Alzheimer's Disease

• Main Author: Védís Helgadóttir 1997-
• Other Authors: Háskóli Íslands
• Format: Thesis
• Language: English
• Published: 2023
• Subjects: Líf- og læknavísindi; Reykjavík; Iceland
• Online Access: http://hdl.handle.net/1946/43360

Introduction: As the age of the human population increases, the number of Alzheimer‘s disease cases increases every year. The diagnosis of the disease is complicated and a definitive diagnosis is only possible by autopsy. Mild cognitive impairment (MCI) is a predemential state where the patient has slight difficulties with memory and in solving daily life tasks. A strong focus is on finding methods to diagnose Alzheimer‘s disease as early as at the MCI stage. There is a demand for new, non-invasive biomarkers to facilitate the diagnosis of Alzheimer‘s disease. As the retina of the eye is of the same embryological origin as the central nervous system and shares many characteristics with it, it is interesting to look for biomarkers of Alzheimer‘s disease in the retina. Oxygen saturation in retinal vessels can be measured by taking retinal images and utilizing light absorbance to calculate oxygen saturation in the vessels. Oximetry software is used to calculate the oxygen saturation. Methods: In this study, the two newest versions of oximetry software from Oxymap ehf. (Reykjavík, Iceland), were compared to see if there was a difference in measured oxygen saturation in arterioles and venules between the versions. One of the versions is semi-automatic and the other is automatic. Furthermore, oxygen saturation and diameter of retinal vessels in MCI patients and healthy controls were compared. In addition, retinal oxygen saturation, retinal vessel diameter and results from ocular coherence tomography were compared in two groups of MCI patients with different degree of atrophy in the medial temporal lobe. Results: Measured oxygen saturation in arterioles and venules was significantly higher when the automatic oximetry was used. Oxygen saturation in venules was shown to be higher in MCI patients than in healthy controls (p=0.028) and arteriovenous difference was lower in MCI patients (p=0.017). Oxygen saturation in arterioles was lower in MCI patients with MTA score of 2-4, compared with MCI patients with MTA score of ...