The relation between the macular carotenoids and cognitive function in pre-adolescent children
Hamilton, Sarah Saint
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The macular carotenoids lutein (L) and zeaxanthin (Z) are obtained via diet and accumulate in the central retina where they are referred to as macular pigment. The density of this pigment (MPOD) has been positively correlated with cognitive functioning via measures of global cognition, processing speed, and visual-spatial abilities, among others. While improvements in cognitive function have been found in adults, much less is known about how L and Z intake may support or improve cognitive functioning during periods of rapid developmental change, such as childhood and pre-adolescence. This study examines the relation between MPOD and cognitive functioning in 7-13 year old children. MPOD was assessed using heterochromatic flicker photometry (HFP) and was used as the primary variable of interest. Temporal processing speed (measured via critical flicker fusion thresholds; CFF), psychomotor reaction time (fixed and variable; FRT and VRT) and coincidence anticipation timing (CAT) were also assessed. Woodcock-Johnson III composite standard scores (Brief Intellectual Ability, Cognitive Efficiency, Processing Speed, and Executive Processes) were used to assess cognitive functioning controlling for age. Both MPOD and CFF were significantly related to Executive Processes, r(49) = .264, p < .05 and r(47) = .243, p < .05, respectively. CFF was also related to Processing Speed, r(49) = .252, p < .05, and Cognitive Efficiency, r(49) = .286, p < .05. FRT, VRT, and CAT performance were all related to age, therefore partial correlations controlling for age were calculated for these variables. FRT and VRT were significantly related to Executive Processes scores, r(46) = -.260, p < .05 and r(46) = -.253, p < .05, respectively. FRT was also related to Cognitive Efficiency, r(48) = 0.236, p < .05, and number of missed trials at 20 mph on the CAT task was related to Processing Speed scores, r(36) = -.301, p < .05. Our findings support the idea that processing speed is a limiting factor for higher order cognitive functions and demonstrate that MPOD is similarly associated with cognitive functioning in childhood and pre-adolescence as it is in adulthood.