Cognition-Eye-Brain Connection in Alzheimer's Disease Spectrum Revealed by Multimodal Imaging

Area of Science:

• Neuroscience
• Ophthalmology
• Radiology

Background:

• The relationship between cognitive function, eye health, and brain changes in Alzheimer's disease (AD) spectrum disorders is not fully understood.
• Existing research has not conclusively linked these factors across the spectrum of cognitive decline.

Purpose of the Study:

• To investigate the associations between cognitive status, retinal imaging metrics, and brain structural and functional alterations in individuals across the Alzheimer's disease spectrum.
• To explore potential early indicators of cognitive decline through the examination of eye and brain changes.

Main Methods:

• A prospective study involving healthy controls (HC), subjective cognitive decline (SCD), mild cognitive impairment (MCI), and Alzheimer's disease (AD) groups.
• Utilized 3-T MRI (BRAVO and fMRI) for brain volume and functional analysis (FALFF, ReHo).
• Employed optical coherence tomography angiography (OCTA) and a deep learning model (FARGO) to analyze retinal features (FAZ, RNFL, GCL-IPL thickness).
• Multivariable linear regression was used to compare cognition-eye-brain associations across groups.

Main Results:

• In MCI patients, reduced temporal FALFF correlated with decreased RNFL thickness and increased FAZ area.
• In AD patients, reduced occipital ReHo was associated with an enlarged FAZ area.
• SCD individuals exhibited widespread cortical thickening linked to retinal biometrics, particularly reduced GCL-IPL thickness.

Conclusions:

• Brain structure and function are associated with cognitive status and retinal biometrics throughout the Alzheimer's disease spectrum.
• Cognition-eye-brain connections may be detectable in the early stages of cognitive decline, such as in SCD.