Mutlu U, et al. - In this population-based study, the connection of inner retinal layer thickness with prevalent and incident dementia in a general population of Dutch adults was investigated. Researchers observed that thinner retinal nerve fiber layer (RNFL) was correlated with an increased risk of dementia, including Alzheimer disease, implying that retinal neurodegeneration could serve as a preclinical biomarker for dementia.

Methods

• Participants from the prospective population-based Rotterdam Study 45 years and older and had gradable retinal optical coherence tomography images and at baseline, were free from stroke, Parkinson disease, multiple sclerosis, glaucoma, macular degeneration, retinopathy, myopia, hyperopia, and optic disc pathology were recruited from September 2007 to June 2012.
• For the onset of dementia, they were followed up until January 1, 2015.
• Inner retinal layer thicknesses (ie, retinal nerve fiber layer [RNFL]) and ganglion cell–inner plexiform layer (GC-IPL) thicknesses were measured on optical coherence tomography images.
• Odds ratios and hazard ratios for incident dementia per SD decrease in retinal layer thickness adjusted for age, sex, education, and cardiovascular risk factors were the main outcomes and measures.

Results

• Out of 5,065 people eligible for optical coherence tomography scanning, 3,289 (64.9%) (mean [SD] age 68.9 [9.9] years, 1879 [57%] women) were enrolled in the analysis.
• Out of these 3,289 people, 41 (1.2%) already had dementia.
• It was observed that thinner GC-IPL was correlated with prevalent dementia (odds ratio per SD decrease in GC-IPL, 1.37 [95% CI, 0.99-1.90]).
• Researchers did not find association of RNFL with prevalent dementia.
• It was noted that 86 people (2.6%) developed dementia, of whom 68 (2.1%) had Alzheimer disease during 14,674 person-years of follow-up (mean [SD], 4.5 [1.6] years).
• Findings revealed that thinner RNFL at baseline was correlated with an increased risk of developing dementia (hazard ratio per SD decrease in RNFL, 1.44 [95% CI, 1.19-1.75]), which was similar for Alzheimer disease (hazard ratio, 1.43 [95% CI, 1.15-1.78]).
• No association between GC-IPL thickness and incident dementia (hazard ratio, 1.13 [95% CI, 0.90-1.43]) was found.