Abstract
Purpose: :
Macular pigment (MP) is known to improve visual function via a variety of known mechanisms. Recent research suggests that the lutein (L) and zeaxanthin (Z) that compose MP are also optimally placed to influence cognitive function and, potentially, motor function, although the mechanisms for these findings are unknown. Past studies have differed somewhat with respect to which cognitive functions L+Z may influence, as well as the magnitude of those relationships. Given the ubiquitous placement of L+Z in the vision system, the purpose of this study was to determine whether or not MP optical density (as a biomarker of cortical L+Z) was significantly related specifically to visual and visuomotor domains of cognition (e.g., visuospatial cognition, attention, vestibular function) in healthy and cognitively impaired adults.
Methods: :
MP optical density (MPOD) was assessed psychophysically and The Standing Leg Test and Physical Performance Test (short battery, SPPB) was used to assess visuomotor performance in 96 physically healthy adults (M = 63.77 years). The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) was used to assess visuospatial/ constructional performance, and attention in 45 of the 96 participants. Of the 45 participants, 18 met criteria for cognitive impairment as determined by the Clinical Dimentia Rating Scale.
Results: :
MPOD was significantly related to improved balance ability (r = 0.29, n = 96) and visuospatial cognition (r = 0.25, n = 45), independent of cognitive status. The relation between MPOD and visuospatial cognition was stronger in cognitively impaired elders (r = 0.43, n = 18). MPOD was also significantly related to attention, but only in impaired elders (r = 0.47, n = 18).
Conclusions: :
MP has been related to cognitive function, broadly defined, in past research. These results suggest that MP’s relationship with cognition may be particularly strong in the visual domain.
Keywords: macular pigment