Abstract
Purpose: :
We investigated the potential association between cognitive function and retinal morphological changes in a well characterized cohort of older people. Parapapillary atrophy (PPA) is characterized by retinal pigment epithelium (RPE) changes around the optic disc, and shares ophthalmoscopic features with age-related macular degeneration. We explored PPA and macular RPE disease changes as potential markers of cognitive function based on shared features found in age-related eye and brain changes.
Methods: :
A community-dwelling, follow-up cohort of surviving participants (n=250) from the Scottish Mental Survey 1947 undertook a battery of comprehensive cognitive tests that included the Moray House Test (MHT) of general cognitive ability (IQ) at age 11 and 70. All were born in 1936. Colour fundus photographs were taken and assessed by an ophthalmologist masked to the results of the cognitive tests.
Results: :
Analyses of covariance were computed to examine the effect of macular drusen and PPA on MHT IQ scores at age 70. The presence of left macular drusen was associated with lower age 70 MHT IQ scores (mean=97.6, SD=13.7) when compared to those without this abnormality (mean=102.9, SD=10.5). This difference was statistically significant (F (1,173)=5.99, p=.015, 2=.033). Scores on the same MHT test administered at age 11 were also significantly lower in those with left macular drusen at age 70 (mean=97.5, SD=16.0) when compared to IQ scores from a group without this abnormality (mean=104.2, SD=12.98). The difference was statistically significant (F (1,164) = 7.41, p=.007, 2=.043). When age 11 MHT IQ was included as a covariate in the model, age 70 MHT IQ scores were no longer significantly associated with left macular drusen (F (1,161)=1.70, p=.20, 2=.01). Similar analyses using right macular drusen and both left and right PPA yielded non-significant (p>.05) findings when compared with early and late life cognition.
Conclusions: :
The observed association of left macular drusen with IQ results at age 70 was largely accounted for by the association with IQ results at age 11 and as no such association was found for right macular drusen and PPA, caution is required as it could be a type 1 error. However, the significant result raises the interesting possibility that childhood IQ is one of the determinants of macular drusen in old age. The mechanisms by which this association occurs can add to our knowledge about how cognitive differences affect health throughout the lifecourse.
Keywords: aging • imaging/image analysis: non-clinical