Structural and functional correlates of the visual system as marker of aging and neurodegenerative changes in the brain
Aging is a complex and multifactorial physiological process that is influenced by a multitude of genetic, epigenetic, and environmental factors. In recent years, there has been growing interest in elucidating the relationship between the visual system and brain changes in the healthy aging process as well as in age-related neurodegenerative disorders such as dementia. Thought of as an extension of the brain the retina, offers a unique opportunity to visualise and monitor the health and integrity of the brain non-invasively and routinely. Neuroimaging of the visual pathway can be used to evaluate the relationship between retinal changes and brain imaging in healthy aging participants and in patients with neurodegenerative conditions such as Alzheimer’s disease (AD). This study aims to determine whether visual pathway degenerative changes are predictive of or corelate with brain deficits in aging subjects. The study also investigated how retinal and blood analysis including various genetic alterations correlate with brain structural and neuropsychological measures in healthy aging and AD at-risk individuals. These aims are firstly addressed through undertaking a large-scale meta-analysis to identify the association of various retinal OCT (Optical Coherence Tomography) parameters with AD diagnosis and whether retinal measurements can be used to differentiate between AD and control subjects. Secondly a comprehensive cross sectional clinical study to examine the relationships of retinal structural (OCT) and visual functional (multifocal visual evoked potentials, mfVEP) indices with neuropsychological and brain structural measurements in healthy older subjects was performed. Finally, a genetic analysis was conducted to investigate the relationship of known genetic risk factors for AD- APOE (Apolipoprotein E) ε4 allele and BDNF (Brain derived neurotrophic factor) Met/Met polymorphism, on the visual structural, functional, and vascular indices.