Neurodegeneration in Alzheimer’s disease and glaucoma: overlaps and missing links

Abstract

The eye is said to be the window into the brain. Alzheimer’s disease (AD) and glaucoma both being diseases of the elderly, have several epidemiological and histological overlaps in pathogenesis. Both these diseases are neurodegenerative conditions. Over the years, a consensus has developed that both may be two ends of a singular spectrum of diseases. Epidemiological studies have shown that more Alzheimer’s patients may be suffering from glaucoma than general healthy population. Retinal ganglion cell damage is a characteristic of both diseases, along with discovery of amyloid-β and tau protein deposition in the retina and aqueous humor of eye. The latter two proteins are known to be pathognomonic of AD. Other pathways such as the insulin receptor pathway also seem to be affected in both diseases similarly. In spite of these overlaps, there are few missing links which still need more evidence, namely, intraocular pressure mechanisms, cerebrospinal fluid pressure and trans -lamina cribrosa pressure gradients, vascular autoregulation factors, etc. Several factors point towards a common pathogenesis at some level for both diseases and prospective studies are necessary to study the natural course of both diseases.

Role of Retinal Amyloid-β in Neurodegenerative Diseases: Overlapping Mechanisms and Emerging Clinical Applications

“…Patients who have glaucoma and AMD have been associated with an increased risk for AD [ 15 ]. Similarly, AD patients have an increased prevalence for glaucoma with glaucoma observed in 7–24% of AD patients in comparison to 4–10% of healthy controls [ 16 ]. Advanced AMD prevalence was also doubled in AD patients in comparison to controls.…”

Bedeutung von Citicolin bei der Glaukomerkrankung

“…Bei der glaukombedingten Neurodegeneration werden auf molekularer Ebene ähnliche Mechanismen vermutet wie bei chronischen neurodegenerativen Erkrankungen des zentralen Nervensystems, z. B. der Alzheimer-Erkrankung [ 45 ]. Experimentelle Studien an retinalen Zellkulturen und Tiermodellen (chronisch erhöhter IOD, RGZ-Axotomie, Sehnerv-Crush-Modell) weisen darauf hin, dass bei dem glaukomatösen RGZ-Verlust neben dem Augeninnendruck verschiedene Ursachen wie Exzitotoxizität, oxidativer Stress, gestörter axonaler Transport mit Mangel an neurotrophen Faktoren, mitochondriale Dysfunktion und autoimmune Dysregulation involviert sind [ 1 ].…”

The “ocular glymphatic clearance system”: a key missing piece of the Alzheimer’s disease-glaucoma puzzle found?

“…I read with great interest the article recently published in Eye by Sen et al [1]. The authors nicely reviewed overlaps and missing links between Alzheimer's disease (AD) and glaucoma, and concluded that several factors point toward a common pathogenesis at some level for both diseases.…”