Table 1.
Similarities and differences between Alzheimer’s disease and age-related macular degeneration.
| Characteristics | Alzheimer’s Disease | Age-Related Macular Degeneration |
|---|---|---|
| Risk factors | aging, genetic susceptibility, female sex, atherosclerosis, hypertension, diabetes, obesity, unhealthy diet, smoking, sleep disturbances, traumatic brain injury, social isolation | aging, genetic susceptibility, female sex, atherosclerosis, hypertension, diabetes, obesity, unhealthy diet, smoking, UV light, obstructive sleep apnea, sleep disturbances |
| Histopathological findings | senile plaques: extracellular Aβ deposits neurofibrillary tangles: intracellular accumulation of p-Tau protein and vitronectin |
drusen: focal extracellular deposits, accumulate between the RPE and Bruch’s membrane containing Aβ, clusterin, vitronectin, amyloid P, apolipoprotein E, complement regulatory proteins, and inflammatory mediators |
| Aβ protein | the main component of senile plaques | component of subretinal drusen |
| p-Tau deposits | component of neurofibrillary tangles | mildly increased in the RPE |
| Oxidative and metabolic stress |
associated with mental deficiencies and neuronal damage | associated with visual cycle and drusen formation |
| Glial reactivity | astrocytes and microglia around senile plaques | microglia in the subretinal space and surrounding the drusen |
| Non-visual disturbances | cognitive deficits (memory loss, aphasia, apraxia, agnosia), depression, behavioral disturbances, inability for self-care |
decreased verbal fluency and verbal memory, reduced visuospatial processing and attention, cognitive decline, higher risk of dementia |
| Cause of visual disturbances | the loss of GCC | photoreceptor layer damage |
| Location of retinal damage | GCC, RNFL | RPE, photoreceptors |
| Location of brain damage | atrophy of brain frontal, temporal, and parietal lobes, entorhinal cortex, amygdala, and hippocampus | optic tract volume reduction loss of cerebral white matter connectivity in areas responsible for verbal fluency and memory |
| Diagnostic procedures | clinical examination, neuropsychological testing CSF sampling brain imaging: MRI, fMRI, CT PET-CR, amyloid imaging |
ophthalmological examination OCT, OCTA FA, ICGA |
| OCT findings | reduced GCC, GC-IPL, peripapillary RNFL | nonexudative AMD: drusen under the RPE, PED exudative AMD: subretinal fluid, CNV |
| Pleiotropic genes | APOC1–increased risk APOE2 allele–reduced risk APOE4 allele–increased risk |
APOC1–increased risk APOE2 allele–increased risk APOE4 allele–reduced risk |
UV: ultraviolet; Aβ: amyloid β; p-Tau: hyperphosphorylated tau; RPE: retinal pigment epithelium; GCC: ganglion cell complex; RNFL: retinal nerve fiber layer; MRI: magnetic resonance imaging; fMRI: functional MRI; CT: computed tomography; PET: positron emission tomography; CSF: cerebrospinal fluid; OCT: optical coherent tomography; OCTA: OCT angiography; FA: fluorescein angiography; ICGA: indocyanine green angiography; GC-IPL: macular ganglion cell-inner plexiform layer; PED: pigment epithelial detachment; CNV: choroidal neovascularization; APOC1: Apolipoprotein C-1 gene; APOE: Apolipoprotein E gene.