Abstract
In this case control study, we examined the retinal thickness of the different layers in the macular region and peripapillary retinal nerve fiber layer (RNFL) with optical coherence tomography (OCT) in healthy cognitive subjects (from 51 to 74 years old) at high genetic risk for developing Alzheimer’s disease (AD). Thirty-five subjects with a family history of Alzheimer disease (AD) (FH+) and ApoE ɛ4 carriers and 29 age-matched control subjects without a family history of AD (FH−) and ApoE ɛ4 non-carriers were included. Compared to FH− ApoE ɛ4 non-carriers, in FH+ ApoE ɛ4 carriers, there were statistically significant decreases (p < 0.05) in (i) the foveal area of mRNFL; (ii) the inferior and nasal sectors in the outer and inner macular ring in the inner plexiform layer (IPL); (iii) the foveal area and the inferior sector in the outer macular ring in the inner nuclear layer (INL); and (iv) the inferior sector of the outer macular ring in the outer plexiform layer (OPL). However, no statistically significant differences were found in the peripapillary thickness of RNFL between both study groups. In subjects with cognitive health and high genetic risk for the development of AD, initial changes appeared in the macular area. OCT could be a promising, cost-effective and non-invasive test useful in early AD, before the onset of clinical symptoms.
Highlights
One of the main genetic risk factors for developing sporadic Alzheimer’s Disease (AD) is having a first-degree family history of the disease [1], another major genetic risk factor is mediated by apolipoprotein E (ApoE) [2]
These changes, which were reported in previous studies, suggested that changes in the retinal nerve fiber layer (RNFL) thickness could be used as an early marker of AD-related brain atrophy [27,36]
A decrease in pRNFL thickness has been correlated with impaired cognition during disease progression [37,38,39,40]
Summary
One of the main genetic risk factors for developing sporadic Alzheimer’s Disease (AD) is having a first-degree family history of the disease [1], another major genetic risk factor is mediated by ApoE [2]. This gene has been implicated in modulating the metabolism and aggregation of Aβ [3]. ApoE 4 plus high levels of amyloid beta (Aβ) proteins are associated with episodic memory decline and high risk for clinical AD [10], and ApoE 4 carriers are more vulnerable to environmental factors [11]
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