Ocular Manifestations of Alzheimer’s Disease in Animal Models

Parnell, Miles; Guo, Li; Abdi, Mohamed; Cordeiro, M. Francesca

doi:10.1155/2012/786494

Cited by 47 publications

(42 citation statements)

References 131 publications

(153 reference statements)

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“…Studies have shown that the cognitive impairment in Alzheimer's disease as determined by mini-mental status examination has a positive correlation with the reduction in macular volume (Parnell et al 2012). In the patients with mild cognitive impairment, which is an early stage of Alzheimer's disease, significant reduction in the retinal nerve fibre layer has been shown in studies (Iseri et al 2006).…”

Section: Results Of Review Of Systematic Evidencementioning

confidence: 99%

Can the retina be used to diagnose and plot the progression of Alzheimer's disease?

Mahajan

Votruba

2017

Acta Ophthalmologica

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Alzheimer's disease (AD) is a neurodegenerative disease and the most common cause of senile dementia. It impairs the quality of life of a person and their family, posing a serious economic and social threat in developed countries. The fact that the diagnosis can only be definitively made post‐mortem, or when the disease is fairly advanced, presents a serious problem if novel therapeutic interventions are to be devised and used early in the course of the disease. There is therefore a pressing need for more sensitive and specific diagnostic tests with which we can detect AD in the preclinical stage. The tau proteins and beta‐amyloid proteins start to accumulate 20 years before the symptoms begin to manifest. Detecting them in the preclinical stage would be a potential breakthrough in the management of AD. A high degree of clinical suspicion is needed to correlate problems in cognition with the changes in the eye, particularly the retina, pupil and ocular movements, so that the disease can be detected early and managed in the prodromal phase. In this systematic review, we ask the question whether the retina can be used to make a specific and early diagnosis of AD.

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Section: Results Of Review Of Systematic Evidencementioning

confidence: 99%

Can the retina be used to diagnose and plot the progression of Alzheimer's disease?

Mahajan

Votruba

2017

Acta Ophthalmologica

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“…Other transgenic mice models have suggested that the inner plexiform layer may be a more sensitive biomarker for detecting AD-related changes compared with RGCs, 70,80 making it difficult to draw firm conclusions. 102 However, both human and mouse studies suggest that AD-related pathology is seen in the retina. RGC loss may be a useful biomarker for assessing the neurodegenerative processes in AD, whether it reflects local pathology or reflects global loss of cortical neurons.…”

Section: The Ganglion Cell Layer In Admentioning

confidence: 99%

How strong is the relationship between glaucoma, the retinal nerve fibre layer, and neurodegenerative diseases such as Alzheimer’s disease and multiple sclerosis?

Jones-Odeh

Hammond

2015

Eye

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Glaucoma is a neurodegenerative disorder with established relationships with ocular structures such as the retinal nerve fibre layer (RNFL) and the ganglion cell layer (GCL). Ocular imaging techniques such as optical coherence tomography (OCT) allow for quantitative measurement of these structures. OCT has been used in the monitoring of glaucoma, as well as investigating other neurodegenerative conditions such as Alzheimer's disease (AD) and multiple sclerosis (MS). In this review, we highlight the association between these disorders and ocular structures (RNFL and GCL), examining their usefulness as biomarkers of neurodegeneration. The average RNFL thickness loss in patients with AD is 11 μm, and 7 μm in MS patients. Most of the studies investigating these changes are cross-sectional. Further longitudinal studies are required to assess sensitivity and specificity of these potential ocular biomarkers to neurodegenerative disease progression. Eye (2015Eye ( ) 29, 1270Eye ( -1284 doi:10.1038/eye.2015; published online 4 September 2015 IntroductionGlaucoma is a neurodegenerative optic neuropathy manifesting with progressive retinal ganglion cell (RGC) and axonal loss, which can result in visual field defects and blindness because of permanent cellular and neuronal damage. Subjective clinical examination of the optic nerve head (ONH) allows for assessment and monitoring of the structural changes associated with glaucoma. However, objective detection of defects in the peripapillary retinal nerve fibre layer (RNFL) by ophthalmoscopy is difficult. The relationship between glaucoma progression and the structural changes observed at the ONH, RGC layer, and RNFL in glaucoma is well established. [1][2][3][4] Early diagnosis and treatment of glaucoma is vital to maintain visual field, as loss of RGCs is irreversible, 5 and even before any detectable visual field defects, there is a substantial loss of RGCs. Morphological abnormalities can develop 3-5 years before any functional loss is detected. 6 Since the introduction of ocular imaging techniques such as optical coherence tomography (OCT), peripapillary RNFL thickness measurements have been used for the detection and monitoring of glaucoma. 7,8 However, the use of OCT has extended beyond RNFL measurements for glaucoma, and has also been used in the investigation of other neurodegenerative disorders such as Alzheimer's disease (AD) 9-11 and multiple sclerosis (MS). [12][13][14] In addition, given the similarities of brain and retinal foetal angiogenesis, 15,16 retinal microvasculature has also been investigated as a biomarker of changes in cerebral vasculature and cognitive decline. [17][18][19] In this review, we examine the relationships between glaucoma, neurodegenerative disease, and cognitive impairment, and the use of RNFL thickness and RGC loss as potential ocular biomarkers for neurodegenerative disorders such as AD and MS. We review the strength of associations between RNFL and RGC and Eye (2015Eye ( ) 29, 1270Eye ( -1284Eye ( © 2015 Macmillan Publis...

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“…This was further validated by other independent studies on AD patients [1, 113, 178] that parallel findings in animal models of the disease. The latter, predominantly involving transgenic (Tg) rodents, reported similar retinal patterns, where Aβ deposits often colocalize with sites of apoptosis, neuroinflammation, impairments of function and structure, and plaque formation that even precedes that seen in the brain [46, 107, 108, 139, 148, 149, 152]. …”

Section: Introductionmentioning

confidence: 99%

Ocular indicators of Alzheimer’s: exploring disease in the retina

et al. 2016

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Although historically perceived as a disorder confined to the brain, our understanding of Alzheimer’s disease (AD) has expanded to include extra-cerebral manifestation, with mounting evidence of abnormalities in the eye. Among ocular tissues, the retina, a developmental outgrowth of the brain, is marked by an array of pathologies in patients suffering from AD, including nerve fiber layer thinning, degeneration of retinal ganglion cells, and changes to vascular parameters. While the hallmark pathological signs of AD, amyloid β-protein (Aβ) plaques and neurofibrillary tangles (NFT) comprising hyperphosphorylated tau (pTau) protein, have long been described in the brain, identification of these characteristic biomarkers in the retina has only recently been reported. In particular, Aβ deposits were discovered in post-mortem retinas of advanced and early stage cases of AD, in stark contrast to non-AD controls. Subsequent studies have reported elevated Aβ42/40 peptides, morphologically diverse Aβ plaques, and pTau in the retina. In line with the above findings, animal model studies have reported retinal Aβ deposits and tauopathy, often correlated with local inflammation, retinal ganglion cell degeneration, and functional deficits. This review highlights the converging evidence that AD manifests in the eye, especially in the retina, which can be imaged directly and non-invasively. Visual dysfunction in AD patients, traditionally attributed to well-documented cerebral pathology, can now be reexamined as a direct outcome of retinal abnormalities. As we continue to study the disease in the brain, the emerging field of ocular AD warrants further investigation of how the retina may faithfully reflect the neurological disease. Indeed, detection of retinal AD pathology, particularly the early presenting amyloid biomarkers, using advanced high-resolution imaging techniques may allow large-scale screening and monitoring of at-risk populations.

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Ocular Manifestations of Alzheimer’s Disease in Animal Models

Cited by 47 publications

References 131 publications

Can the retina be used to diagnose and plot the progression of Alzheimer's disease?

Can the retina be used to diagnose and plot the progression of Alzheimer's disease?

How strong is the relationship between glaucoma, the retinal nerve fibre layer, and neurodegenerative diseases such as Alzheimer’s disease and multiple sclerosis?

Ocular indicators of Alzheimer’s: exploring disease in the retina

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