==== Front Innov Aging Innov Aging innovateage Innovation in Aging 2399-5300 Oxford University Press US 10.1093/geroni/igaa057.1583 igaa057.1583 Abstracts Session 2999 (Paper) Experiences in Long-Term Care AcademicSubjects/SOC02600 Mediterranean versus Western diet effects on cerebral cortical thickness and volume in cynomolgus monkeys Frye Brett 1 Craft Suzanne 1 Register Thomas 1 Kim Jeongchul 1 Whitlow Christopher 1 Lockhart Samuel 1 Shively Carol 2 1 Wake Forest School of Medicine, Winston-Salem, North Carolina, United States 2 Wake Forest University Alzheimer’s Disease Research Center, Winston-Salem, North Carolina, United States 2020 16 12 2020 16 12 2020 4 Suppl 1 Program Abstracts from The GSA 2020 Annual Scientific Meeting “Turning 75: Why Age Matters”489 490 © The Author(s) 2020. Published by Oxford University Press on behalf of The Gerontological Society of America.2020This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.Abstract Diet may influence the risk for cognitive decline and neurodegenerative disorders, including Alzheimer’s disease (AD), but these relationships are difficult to study in humans. Cynomolgus macaques (Macaca fascicularis) are appropriate models for investigations of diet effects on the brain because, like humans, they are omnivorous, have complex central nervous systems, are susceptible to diet-induced diseases, and accumulate amyloid and tauopathies with age. Using structural magnetic resonance imaging, we examined diet effects on brain anatomy by measuring thickness and volume of several areas relevant to AD in 38 middle-aged females, at baseline and after Mediterranean or Western diet consumption for 36 months (equivalent to a 9-year follow-up in humans). Using repeated measures analysis, cortical thicknesses generally increased in the Western diet group. Western diets also resulted in increases in total brain volume and cortical gray matter and decreases in cerebrospinal fluid, white matter, and deep gray matter (striatum and thalamus) (all p’s≤0.05). In contrast, thicknesses and volumes generally remained unchanged in animals consuming Mediterranean diets. Taken together, these findings demonstrate that Western diets induce widespread structural shifts which may increase risk of cognitive decline and neuropathology, whereas Mediterranean diets may exert a stabilizing influence on the brain. This study provides important insights about the significance of diet on brain structure and lays the groundwork for future investigations to uncover the molecular underpinnings of diet-induced changes in the brain. Mediterranean diet may protect against structural changes in brain that occur with age in those consuming a Western diet.