Awareness of visual impairment in mild AD

Abstract

Objective: To evaluate self-awareness of visual impairment and determine cognitive predictors of awareness in AD.

Methods: 68 participants with early AD (mean age=74.22) underwent cognitive tests. Vision impairment was defined by scores [[gt]]1 SD poorer than non-demented control (N=135, mean age=70.21) scores on Useful Field of View (UFOV) Contrast Sensitivity (CS) tests. The VFQ-25 questionnaire provided a standardized self-report of visual impairment. A composite measure used 7 key questions (#2, 5, 6–10; 0–4 scale). We also evaluated questions more specific to UFOV (#7/10 on visual search of a crowded shelf/ the periphery) and CS (#2/5/6 on eyesight/reading/seeing up close).

Results: 57/68 AD subjects had UFOV impairments and 51/68 had CS impairments. Across all AD subjects there were no significant Spearman correlations between self-report of impairments on the VFQ and visual deficit magnitudes, suggesting overall lack of awareness. Subsequently we indexed awareness by plotting deficit magnitude for UFOV and CS against self-report for the VFQ responses. Diagonal lines through scatter plots of vision test scores versus VFQ responses modeled the ideal situation in which greater deficits produce more complaints. Distance between a data point and the diagonal line indexed awareness. Visual and verbal memory, executive functions and overall cognitive function scores predicted awareness of UFOV and CS impairments based on the composite and specific questions from the VFQ (PConclusions: AD impairs visual functions and awareness of those impairments. This unawareness (a.k.a, anosognosia) may reflect a metacognitive failure to develop an accurate internal representation of current visual ability due to impaired encoding and monitoring of recurrent instances of failure in everyday visual activities. Primary deficits in memory and executive function contribute to this unawareness.

Footnotes

 Acknowledgment: Supported by NIH AG17177.  NIH AG 17177.