Longitudinal retinal layer changes in preclinical Alzheimer's disease

Area of Science:

• Neuroscience
• Ophthalmology
• Biomarker Discovery

Background:

• Alzheimer's disease (AD) is characterized by amyloid-beta (Aβ) plaques.
• Retinal thickness changes detected by optical coherence tomography (OCT) are potential early biomarkers for AD.
• Preclinical AD research focuses on identifying reliable biomarkers in cognitively normal individuals.

Purpose of the Study:

• To investigate retinal thickness changes in cognitively normal individuals with and without amyloid-beta (Aβ) positivity, as determined by positron emission tomography (PET).
• To assess the potential of OCT as a longitudinal screening tool for preclinical AD.
• To explore the association between Aβ burden and changes in retinal layer thickness.

Main Methods:

• A cohort of 145 cognitively healthy monozygotic twins aged ≥60 underwent [18F] flutemetamol PET for Aβ detection.
• Cortical Aβ was assessed visually and quantified using binding potential.
• OCT was performed at baseline and 22 months to measure retinal thickness changes in macular and peripapillary regions.

Main Results:

• Eleven percent of participants were positive for Aβ.
• No significant differences in the rate of retinal thickness change were observed between Aβ-positive and Aβ-negative individuals.
• A positive association was found between Aβ binding potential and preserved inner plexiform layer (IPL) thickness over time in the inner macular ring.

Conclusions:

• OCT did not reveal differences in retinal layer thickness changes between Aβ+ and Aβ- individuals, suggesting limited utility as a longitudinal screening tool for preclinical AD.
• Higher baseline Aβ burden was associated with less thinning of the IPL, indicating potential for IPL changes as a biomarker.
• Further research into inner plexiform layer changes may provide new insights into early AD detection.