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Elizabeth Couser, Corinne Pettrigrew, Anja Soldan, Marilyn S Albert; Cognitive measure may identify atrophy in visual brain regions associated with posterior cortical atrophy.. Invest. Ophthalmol. Vis. Sci. 2017;58(8):5133.
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© ARVO (1962-2015); The Authors (2016-present)
To determine whether a simple ratio of cognitive measures is related to atrophy in posterior brain regions, as measured on magnetic resonance imaging (MRI) scans, and thereby identifies patients with posterior cortical atrophy (PCA). PCA affects a small percentage of individuals with Alzheimer’s disease (AD) pathology and is characterized by significant visual-perceptual impairment. There are no established diagnostic criteria for PCA and misdiagnosis of PCA is common. This study tested whether a simple ratio score of visual-perceptual performance to memory performance was associated with MRI measures of visual association cortices in a subgroup of patients with suspected PCA.
Analyses included 142 patients with AD dementia (M age = 74.5) from the Alzheimer’s Disease Neuroimaging Initiative. Ratio scores, reflecting constructional praxis performance (a measure of visual spatial ability) relative to memory performance, were calculated for each patient using subscales of the ADAS-Cog. Atrophy was estimated using structural MRI measures (volume, thickness) of cortical regions involved in visual processing.
Using the ADAS-Cog ratio scores, 12 patients were classified as possible PCA subjects (M age = 69.9). Relative to the typical AD group, the ‘PCA’ group had smaller volumes and lower thicknesses in two visual brain regions (p <.05), and approached significance in a composite score of visual brain regions. Several MRI measures were significantly related to higher scores on the ADAS-cog ratio in the ‘PCA’ subgroup but not in the group with ADAS-cog ratios in the ‘typical’ range (p<.05). Additionally, logistic regressions showed that the degree of atrophy in several regions predicted PCA group status (p<.05).
The results suggest that the ADAS-Cog based ratio score of constructional praxis to episodic memory recall is associated with significant atrophy in posterior cortical regions. This measure may be useful for identifying individuals with suspected PCA.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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