Abstract
Purpose::
To determine if vision function can predict future cognitive status.
Methods::
A battery of vision tests was administered to 570 older participants ranging in age from 58.4 to 101.9 years (mean=73.6 years). The vision tests included numerous measures of spatial vision and two measures of visual field. The "standard" visual field tested the detection of supra-threshold targets presented along 5 meridia at eccentricities from 10 to 70 deg while passively fixating a central target. The "attentional" visual field repeated the test while asking the participant to count silently the number of times the central fixation target was briefly extinguished. Each visual field test took about 3 minutes. Both field tests were corrected for spurious responses. The "attentional" field was also corrected for the mismatch between actual and reported number of flashes of the fixation target. The visual field results are expressed as the total number of locations not seen for the "standard" field and the difference in total errors between the two tests for the attentional component. The test of cognitive status, the Mental Alternation Test (MAT) was administered on average 4.4 years later. The task requires the participant to verbally alternate between letters and numbers for a period of 30 seconds. The score is the number of correct alternations.
Results::
The average score for the MAT was 23.3 (range 1-51). Only 18.9% of the sample scored less than 15 on the Mental Alternation Test, the criterion for dementia. The "attentional" visual field showed dramatic losses with age while the "standard" field showed small changes with age. As expected, the most peripheral locations were most frequently missed on the attentional task but surprisingly the central locations were missed more frequently than those in the mid-periphery. Multiple regression analysis showed that only the visual field measures remained significant when controlling for age, gender and years of education. The attentional component contributed most to the unique variance.
Conclusions::
A simple visual divided attention task predicts cognitive status as determined by the Mental Alternation Test.
Keywords: aging: visual performance • visual fields