Abstract
BackgroundOptical coherence tomography (OCT) of the retina is a fast and easily accessible tool for the quantification of retinal structural measurements. Multiple studies show that patients with Alzheimer’s disease (AD) exhibit thinning in several retinal layers compared to age-matched controls. Subjective cognitive decline (SCD) has been proposed as a risk factor for progression to AD. There is little data about retinal changes in preclinical AD and their correlation with amyloid-β (Aβ) uptake.AimsWe investigated the association of retinal thickness quantified by OCT with Aβ accumulation and conversion to mild cognitive impairment (MCI) over 24 months in individuals with SCD.MethodsOne hundred twenty-nine individuals with SCD enrolled in Fundació ACE Healthy Brain Initiative underwent comprehensive neuropsychological testing, OCT scan of the retina and florbetaben (FBB) positron emission tomography (PET) at baseline (v0) and after 24 months (v2). We assessed the association of sixteen retinal thickness measurements at baseline with FBB-PET status (+/−) and global standardize uptake value ratio (SUVR) as a continuous measure at v0 and v2 and their predictive value on clinical status change (conversion to mild cognitive impairment (MCI)) at v2.ResultsMean age of the sample was 64.72 ± 7.27 years; 62.8% were females. Fifteen participants were classified as FBB-PET+ at baseline and 22 at v2. Every 1 μm of increased thickness in the inner nasal macular region conferred 8% and 6% higher probability of presenting a FBB-PET+ status at v0 (OR = 1.08, 95% CI = 1.02–1.14, p = 0.007) and v2 (OR = 1.06, 95% CI = 1.02–1.11, p = 0.004), respectively. Inner nasal macular thickness also positively correlated with global SUVR (at v0: β = 0.23, p = 0.004; at v2: β = 0.26, p = 0.001). No retinal measurements were associated to conversion to MCI over 24 months.ConclusionsSubtle retinal thickness changes in the macular region are already present in SCD and correlate with Aβ uptake.
Highlights
In the past few decades, there has been an increase of the global prevalence of dementia that is threatening the sustainability of healthcare systems worldwide
Subtle retinal thickness changes in the macular region are already present in Subjective cognitive decline (SCD) and correlate with Aβ uptake
Forty-three individuals were excluded from the analysis due to eyerelated pathologies that could potentially affect retinal thickness measurements
Summary
In the past few decades, there has been an increase of the global prevalence of dementia that is threatening the sustainability of healthcare systems worldwide. Longitudinal studies have shown that elderly individuals with SCD have an increased risk of progression to cognitive impairment and dementia [5], more functional deficits [6] and higher prevalence of post-mortem AD pathology [7]. All these data point to SCD being the earliest clinical detectable point of the AD clinical continuum. There is little data about retinal changes in preclinical AD and their correlation with amyloid-β (Aβ) uptake
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