Abstract
Purpose: :
Anatomical studies have shown that the cellular losses and dysfunctions seen in Alzheimer's Disease (AD) demonstrate a similar pathogenesis to the cellular loses and dysfunctions which occur in the presence of retinal diseases, such as Age-related Macular Degeneration (AMD) or glaucoma. Furthermore, a number of studies have recently demonstrated co-morbidity between retinal diseases and pathological cognitive impairment, above what would be expected by chance. However, this co-morbidity with cognitive loss has only been found among individuals with relatively severe vision loss due to AMD and glaucoma. Most often, cognitive testing consists of a modified version of the Mini-Mental State Exam (MMSE), a short screening tool. Recently the MoCA (Montreal Cognitive Assessment) has been developed as an alternative to the MMSE. Although highly correlated with the MMSE, the MoCA may be a more sensitive tool for detecting Mild Cognitive Impairment (MCI), which may precede AD. Both tests are scored out of a possible 30 points and have the same cut-off of 26, a score below this being suggestive of a cognitive impairment. In the present study, the MMSE and the MoCA were compared among individuals with early atrophic AMD, glaucoma and no visual pathology.
Methods: :
Number of participants in each group and their respective mean ETDRS acuities OU were: 17 with AMD (20/27), 19 with glaucoma (20/36) and 16 visually healthy people (20/23). Participants ranged in age between 47 and 89, with a mean of 72 years. The MMSE and the MoCA were administered in random order to all participants.
Results: :
Chi Square analysis indicated a significantly higher proportion of individuals scoring below the cut-off point of 26 for possible cognitive impairment on the MoCA, chi squared (2) = 32.52 p<.001.
Conclusions: :
Given the results of our chi-squared analysis, the MoCA (but not the MMSE) may be detecting the presence of subtle cognitive changes in a population with early progressive retinal disease. Given the suggested co-morbidity between retinal diseases and cognitive impairment, this study may add weight to the possibility that age-related visual disorders and MCI/eventual AD share a common pathogenesis.
Keywords: retina • memory • aging