The effect of age-related macular degeneration on non-verbal neuropsychological test performance

Existing neuropsychological instruments used to clinically diagnose dementia, many of which are based upon visual image processing, do not take into account the different types of sensory loss presented by low vision patients. The purpose of the present study is therefore to assess the effects of low vision on non-verbal neuropsychological test performance. A retrospective chart review identified patients with age-related macular degeneration (ARMD), central vision loss, and an age-matched control group. All participants completed a depression inventory and a «blind» version of the mini-mental Status examination in order to “screen” for dementia. Each group was assessed with a pre-determined battery of non-verbal neuropsychological tests differing in their visual image characteristics (size of test items, contrast, chromaticity, glare, etc.). As expected, preliminary results show a decrease in performance across non-verbal tests for the ARMD group, particularly for tests characterized by visual scanning strategies (Trail Making Test (D-KEFS)) and small item sizes (i.e. Digit Symbol and Symbol Search WAIS subtests). Results demonstrate that ARMD affects performance on certain non-verbal test more than others. All participants will be re-assessed within a 6-week period using the same battery of tests in modified versions (i.e. magnified and polarity reversed). If the implemented visual-test modifications control for decrease in performance due to sensory loss, these adapted tests may be used to compliment existing «blind» cognitive screening presently used to assess low-vision patients, resulting in a more precise assessment of cognitive functioning for this low-vision group.