Age-related retinal thickness in Down's syndrome: A high-risk population for dementia

Literature Commentary

The format of Lit Commentary is a bit different beginning in this issue to save space in the Journal. We no longer start with a list of the papers reviewed, and we no longer print a copy of the abstracts, as the articles are easily available online. We welcome feedback about these changes. In this issue of JNO Drs. Mark L. Moster, Marc Dinkin, and Deborah I. Friedman discuss the following six articles.

Macular and choroidal thickness in Down syndrome by swept-source optical coherence tomography (SS-OCT)

Down syndrome (DS) is associated with certain structural and functional disorders in the whole visual system. The purpose was to compare retinal and choroidal thickness using swept-source optical coherence tomography (SS-OCT) in DS subjects with controls. This cross-sectional study included 100 eyes of 52 DS subjects and 78 eyes of 39 matching age and axial length controls. Our results showed that inner or outer retinal and ganglionar thickness showed no significant differences between DS and control group (p > 0.05). However, retinal foveal thickness (rFT), ganglion foveal thickness (gFT) were significantly higher in DS group than in controls, whereas choroidal foveal thickness (cFT) and some choroidal quadrants of inner and outer rings were significantly lower (p < 0.05). This the first pilot study to provide information about macular and choroidal thicknesses in SD using SS-OCT compared to controls. Further analyses with larger numbers of subjects are needed to confirm our results.

Increased choroidal thickness in adults with Down syndrome

INTRODUCTION

People with Down syndrome (DS) are particularly susceptible to Alzheimer's disease (AD) due to the triplication of the amyloid precursor protein (APP) gene. In this cross-sectional study, we hypothesized that choroidal thinning reported in sporadic AD (sAD) is mirrored in adults with DS.

METHODS

The posterior pole of the eye for 24 adults with DS and 16 age-matched controls (Ctrl) were imaged with optical coherence tomography. Choroidal thickness (ChT) was measured and analyzed in relation to cognitive status and cerebral amyloid beta (Aβ) load.

RESULTS

ChT was increased in people with DS (pwDS) compared to Ctrl. This increase was associated with gender differences and positively correlated with cerebral Aβ load in a small subset. There was no significant correlation detected between ChT and age or cognitive status.

DISCUSSION

In contrast to sAD this study found a significantly thicker choroid in pwDS. Whether these changes are related to Aβ pathology in DS needs further investigation.

Macular and choroidal thickness in Down syndrome by swept-source optical coherence tomography (SS-OCT)

Down syndrome (DS) is associated with certain structural and functional disorders in the whole visual system. The purpose was to compare retinal and choroidal thickness using swept-source optical coherence tomography (SS-OCT) in DS subjects with controls. This cross-sectional study included 100 eyes of 52 DS subjects and 78 eyes of 39 matching age and axial length controls. Our results showed that inner or outer retinal and ganglionar thickness showed no significant differences between DS and control group (p>0.05). However, retinal foveal thickness (rFT), ganglion foveal thickness (gFT) were significantly higher in DS group than in controls, whereas choroidal foveal thickness (cFT) and some choroidal quadrants of inner and outer rings were significantly lower (p<0.05). This the first pilot study to provide information about macular and choroidal thicknesses in SD using SS-OCT compared to controls. Further analyses with larger numbers of subjects are needed to confirm our results.

Retinal Levels of Amyloid Beta Correlate with Cerebral Levels of Amyloid Beta in Young APPswe/PS1dE9 Transgenic Mice before Onset of Alzheimer's Disease

Objectives

Retina abnormalities are related to cognitive disorders in patients with Alzheimer's disease (AD). Retinal amyloid beta (Aβ) can be labeled by curcumin. We measured Aβ content in the cerebrum and retina of APPswe/PS1dE9 (APP) transgenic mice with early age to investigate the correlation between cerebrum and retina.

Methods

APP mice and age-matched wild-type mice were investigated every month from age 2 months to 6 months to assess changes in Aβ content in the retina and cerebrum. At the beginning of each month, mice were fed a curcumin diet (50 mg/kg/day) for 7 consecutive days. The Aβ levels in the retina and cerebrum were measured by ELISAs. Correlations were identified between retinal and cerebral Aβ contents using Pearson's correlation.

Results

In the absence of curcumin, there was a significant correlation between Aβ contents in the retina and cerebrum of APP mice (r = 0.7291, P = 0.0014). With increasing age, Aβ-mediated degenerative change in the cerebrum (P < 0.001 in 5 months) and retina (P < 0.01 in 5 months) increased significantly. The inhibitory effect of curcumin on the Aβ level was significant in the cerebrum (P < 0.001) and retina (P < 0.01) of older APP mice in the early stage of life.

Conclusion

We observed a significant correlation between the Aβ content in the retina and Aβ content in the cerebrum of APP mice. Our data suggest an appropriate time to measure retinal Aβ. Although curcumin can label Aβ in the retina, it also suppresses Aβ levels and weakens the degree of correlation between Aβ in cerebrum and retina tissues.