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Open Access Highly Accessed Research article

Retinal nerve fiber layer thickness and cognitive ability in older people: the Lothian Birth Cohort 1936 study

Augustinus Laude12*, Gerassimos Lascaratos1, Ross D Henderson3, John M Starr4, Ian J Deary3 and Baljean Dhillon15

Author Affiliations

1 Princess Alexandra Eye Pavilion, NHS Lothian, Scotland, UK

2 National Healthcare Group Eye Institute, Tan Tock Seng Hospital, Singapore 308433, Singapore

3 Centre for Cognitive Ageing and Cognitive Epidemiology, Department of Psychology, University of Edinburgh, Scotland, UK

4 Centre for Cognitive Ageing and Cognitive Epidemiology, Geriatric Medicine Unit, University of Edinburgh, Scotland, UK

5 School of Clinical Sciences, University of Edinburgh, Scotland, UK

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BMC Ophthalmology 2013, 13:28  doi:10.1186/1471-2415-13-28

Published: 3 July 2013

Abstract

Background

This study aims to examine the relationship between the retinal nerve fiber layer (RNFL) thickness as measured by optical coherence tomography (OCT) and lifetime cognitive change in healthy older people.

Methods

In a narrow-age sample population from the Lothian Birth Cohort 1936 who were all aged approximately 72 years when tested, participants underwent RNFL measurements using OCT. General linear modeling was used to calculate the effect of RNFL thickness on three domains; general cognitive ability (g-factor), general processing speed (g-speed) and general memory ability (g-memory) using age at time of assessment and gender as co-variates.

Results

Of 105 participants, 96 completed OCT scans that were of suitable quality for assessment were analyzed. Using age and gender as covariates, we found only one significant association, between the inferior area RNFL thickness and g-speed (p = 0.049, η2 = 0.045). Interestingly, when we included age 11 IQ as a covariate in addition to age and gender, there were several statistically significant associations (p = 0.029 to 0.048, η2 = 0.00 to 0.059) in a negative direction; decreasing scores on measures of g-factor and g-speed were associated with increasing RNFL thickness (r = −0.229 to −0.243, p < 0.05). No significant associations were found between RNFL thickness and g-memory ability. When we considered the number of years of education as a covariate, we found no significant associations between the RNFL thickness and cognitive scores.

Conclusions

In a community dwelling cohort of healthy older people, increased RNFL thickness appeared to be associated with lower general processing speed and lower general cognitive ability when age 11 IQ scores were included as a covariate.

Keywords:
Cognitive; Elderly; Principal components analysis; Optical coherence tomography; Retinal nerve fiber layer