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Matthew Flood, Ruchi Shah, Nelligen Matthew, Duke Han, Bruce Gaynes; Retention of memory skill among older adults who experienced profound vision loss across their lifetime. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):510.
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© ARVO (1962-2015); The Authors (2016-present)
Visual decline is thought to be associated with cognitive impairment in old age, yet, many individuals who experience blindness their entire life maintain cognitive skill well into old age. It is postulated that early cross modal sensory reprocessing allows individuals to compensate for profound early loss of visual stimulation. The purpose of this study was to describe memory skill among older adults who experienced profound vision loss across their lifetime.
The study is a cross-sectional assessment of episodic and working memory in older legally blind non-institutionalized individuals. Subjects were classified as early or late blind (blindness before or after age 16 respectively). A non-randomized sample of consecutively enrolled subjects was examined. Subjects’ demographic data was collected and memory surveys were administered including the WAIS Working Memory Digit Span Forward (DSF), Digit Span Backward (DSB) and the California Verbal Learning Test (CVLT, episodic memory). Mood (Geriatric Depression Scale (GDS), and Personality (NEO Five Factor Inventory) were also evaluated. Historical norms of age matched normally sighted peers were used as control.
Subject age ranged from 57-81 (median 64.5). 7 subjects were deemed early blind and 5 late blind. Mean (SD) scaled t scores for the CVLT, DSF and DSB for all subjects were 50.18 +/- 11.28, 63.44 +/- 11.39 and 61.27 +/- 13.34 respectively. Mean CVLT, DSF and DSB did not differ between early and late blind subjects. Linear regression showed that education but not age was a predictor of working memory as measured by the DSF and DSB tests among both early and late blind subjects (R2 = 0.5622, p = 0.005, R2 = .6053, p =0.003, respectively). No subject demonstrated clinical depression as measured by the GDS.<br />
Older individuals including both the early and late blind retain a level of working and episodic memory equivalent to or exceeding normally sighted peers. Although limited by a small N and potential selection bias, these findings support the notion that cross modal cortical reprocessing that purportedly occurs in blind individuals in early life plays an important compensatory role in cognitive processing that is retained throughout a lifetime.
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