Abstract
Purpose :
To determine if OCT structural measures are associated with cognitive ability in individuals recruited from 2 population-based samples of older adults: a primarily black sample from Jackson, MS, and a predominantly white sample from Washington County, MD. Participants with frank dementia were excluded in order to focus on whether OCT might aid in detection of early stages of cognitive impairment.
Methods :
One randomly selected eye was imaged from 307 and 318 participants from the Jackson and Washington County sites, respectively. Macular OCT images to judge ganglion cell complex (GCC) thickness and peripapillary OCT images to judge nerve fiber layer (NFL) thickness were obtained. Participants had a comprehensive panel of cognitive testing in the prior month, and z-scores from 10 cognitive tests were averaged to generate a score reflecting overall cognitive ability. Linear regression models incorporating spline terms were used to relate axial-length corrected OCT measures with cognition accounting for age, race, gender, education, income level, axial length, and IOP as covariates.
Results :
Imaging of sufficient quality was noted in 579/625 participants, and those with poor images were slightly older than those with sufficient image quality (80 vs 78 years, p=0.03). In multivariable models, axial length corrected NFL thickness was associated with overall cognitive ability (+0.077 z-score units/ 10 micron increment in thickness up to 103 microns, p=0.007), as was greater GCC thickness (+0.085 z-score units/10 micron increment in thickness up to 97 microns, p=0.03). No significant change in cognition was noted with changes in GCC thickness above 97 microns or NFL thickness above 103 microns (p>0.05). Greater axial length was also associated with greater cognitive ability (+0.07 z-score units/1 mm increment, p=0.006). Other significant predictors of worse cognitive ability included older age, male sex, Jackson site, lower educational attainment and lower income (p<0.05 for all).
Conclusions :
Greater Macular GCC and peripapillary NFL thickness are associated with higher cognitive ability, though these cross-sectional associations were of limited clinical significance in the studied cohort. Increased axial length was associated with better cognition, suggesting axial elongation from early-life activities (i.e. reading) may result in better cognition, even in late life.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.