Title : Retinal changes can reflect the altered Alzheimer’s disease brain structural biomarkers
Alzheimer's disease (AD), the most common form of dementia in older adults, is mainly diagnosed based on changes in brain structure. The retina is known as an extension of the central nervous system, neurodegenerative diseases affecting the brain and spinal cord are mirrored in the eye. With the development of noninvasive retinal imaging technologies, including optical coherence tomography (OCT), OCT angiography, research focused on developing retinal imaging as a source of potential biomarkers for Alzheimer’s disease has increased significantly. However, the association between retinal parameters and AD neuroimaging biomarkers particularly structural changes is still unclear. In this cross-sectional study, we recruited 48 subjects, including 27 cognitive impairment (CI) patients and 21 cognitive normal (CN) individuals. All subjects underwent retinal layer thickness and microvascular measurements with optical coherence tomography angiography (OCTA). Gray matter and white matter (WM) data such as T1-weighted magnetic resonance imaging and diffusion tensor imaging were also collected. Besides, hippocampal subfields volumes and WM tracts microstructural alteration as classical AD neuroimaging biomarkers were brought into study. The microvascular and retinal features and their correlation with brain structural imaging markers were further analyzed. We found that CI patients showed the atrophy hippocampal subfields volumes and the altered microstructural integrity of WM tracts compared with CN subjects. Importantly, we detected the significant associations between retinal parameters and gray matter volume of hippocampal subiculum/presuiculum or WM integrity of cingulum hippocampus/uncinate fasciculus in CI patients. These findings suggested that the retinal layer thickness and microvascular measures detected by the OCTA may be a marker for the early prediction of AD-related brain structural changes.