title: Parahippocampal Cortex Mediates the Relationship between Lutein and Crystallized Intelligence in Healthy, Older Adults.
abstract: Introduction:Although, diet has a substantial influence on the aging brain, the relationship between dietary nutrients and aspects of brain health remains unclear. This study examines the neural mechanisms that mediate the relationship between a carotenoid important for brain health across the lifespan, lutein, and crystallized intelligence in cognitively intact older adults. We hypothesized that higher serum levels of lutein are associated with better performance on a task of crystallized intelligence, and that this relationship is mediated by gray matter structure of regions within the temporal cortex. This investigation aims to contribute to a growing line of evidence, which suggests that particular nutrients may slow or prevent aspects of cognitive decline by targeting specific features of brain aging.Methods:We examined 76 cognitively intact adults between the ages of 65 and 75 to investigate the relationship between serum lutein, tests of crystallized intelligence (measured by the Wechsler Abbreviated Scale of Intelligence), and gray matter volume of regions within the temporal cortex. A three-step mediation analysis was implemented using multivariate linear regressions to control for age, sex, education, income, depression status, and body mass index.Results:The mediation analysis revealed that gray matter thickness of one region within the temporal cortex, the right parahippocampal cortex (Brodmann's Area 34), partially mediates the relationship between serum lutein and crystallized intelligence.Conclusion:These results suggest that the parahippocampal cortex acts as a mediator of the relationship between serum lutein and crystallized intelligence in cognitively intact older adults. Prior findings substantiate the individual relationships reported within the mediation, specifically the links between (i) serum lutein and temporal cortex structure, (ii) serum lutein and crystallized intelligence, and (iii) parahippocampal cortex structure and crystallized intelligence. This report demonstrates a novel structural mediation between lutein status and crystallized intelligence, and therefore provides further evidence that specific nutrients may slow or prevent features of cognitive decline by hindering particular aspects of brain aging. Future work should examine the potential mechanisms underlying this mediation, including the antioxidant, anti-inflammatory, and membrane modulating properties of lutein.
authors.affiliation: Decision Neuroscience Laboratory, University of Illinois Urbana-ChampaignUrbana, IL, USA; Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-ChampaignUrbana, IL, USA; Neuroscience Program, University of Illinois Urbana-ChampaignUrbana, IL, USA.
authors.forename: Marta K
authors.initials: MK
authors.lastname: Zamroziewicz
authors.affiliation: Decision Neuroscience Laboratory, University of Illinois Urbana-ChampaignUrbana, IL, USA; Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-ChampaignUrbana, IL, USA.
authors.forename: Erick J
authors.initials: EJ
authors.lastname: Paul
authors.affiliation: Decision Neuroscience Laboratory, University of Illinois Urbana-ChampaignUrbana, IL, USA; Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-ChampaignUrbana, IL, USA.
authors.forename: Chris E
authors.initials: CE
authors.lastname: Zwilling
authors.affiliation: Jean Mayer USDA Human Nutrition Center on Aging, Tufts University Boston, MA USA.
authors.forename: Elizabeth J
authors.initials: EJ
authors.lastname: Johnson
authors.affiliation: Research, Scientific and Medical Affairs, Abbott Nutrition Columbus, OH, USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Kuchan
authors.affiliation: Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-ChampaignUrbana, IL, USA; Neuroscience Program, University of Illinois Urbana-ChampaignUrbana, IL, USA; Department of Psychology, University of Illinois Urbana-ChampaignUrbana, IL, USA; Carle Neuroscience Institute, Carle Foundation HospitalUrbana, IL, USA.
authors.forename: Neal J
authors.initials: NJ
authors.lastname: Cohen
authors.affiliation: Decision Neuroscience Laboratory, University of Illinois Urbana-ChampaignUrbana, IL, USA; Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-ChampaignUrbana, IL, USA; Neuroscience Program, University of Illinois Urbana-ChampaignUrbana, IL, USA; Department of Psychology, University of Illinois Urbana-ChampaignUrbana, IL, USA; Carle Neuroscience Institute, Carle Foundation HospitalUrbana, IL, USA; Department of Internal Medicine, University of Illinois Urbana-ChampaignUrbana, IL, USA; Department of Speech and Hearing Science, University of Illinois Urbana-ChampaignUrbana, IL, USA; Institute for Genomic Biology, University of Illinois Urbana-ChampaignChampaign, IL, USA.
authors.forename: Aron K
authors.initials: AK
authors.lastname: Barbey
keywords: cognitive aging; crystallized intelligence; lutein; nutritional cognitive neuroscience; parahippocampal cortex