Vitolins, M. Z. | Search bioRxiv

bioRxiv2020

Mediterranean Diet, Stress Resilience, and Aging in Nonhuman Primates

Persistent psychological stress increases the risk of many chronic diseases of aging. Little progress has been made to effectively reduce stress responses or mitigate stress effects suggesting a need for better understanding of factors that influence stress responses. Limited evidence suggests that diet may be a factor in modifying the effects of stress. However, long-term studies of diet effects on stress reactive systems are not available, and controlled randomized clinical trials are difficult and costly. Here we report the outcomes of a controlled, randomized preclinical trial of the effects of long-term consumption (31 months, [~] equivalent to 9 human years) of Western versus Mediterranean - like diets on behavioral and physiological responses to acute (brief social separation) and chronic (social subordination) psychosocial stress in 38 adult, socially-housed, female cynomolgus macaques. Compared to animals fed a Western diet, those fed the Mediterranean diet exhibited enhanced stress resilience as indicated by lower sympathetic activity, brisker and more overt heart rate responses to acute stress, more rapid recovery, and lower cortisol responses to acute psychological stress and adrenocorticotropin (ACTH) challenge. Furthermore, age-related increases in sympathetic activity and cortisol responses to stress were delayed by the Mediterranean diet. Population level diet modification in humans has been shown to be feasible. Our findings suggest that population-wide adoption of a Mediterranean-like diet pattern may provide a cost-effective intervention on psychological stress and promote healthy aging with the potential for widespread efficacy. HighlightsO_LIThere is no population level treatment to reduce stress and associated disease. C_LIO_LIMediterranean diet reduced sympathetic activity. C_LIO_LIMediterranean diet reduced cortisol response to acute stress and to ACTH challenge. C_LIO_LIMediterranean diet delayed age-related increases in sympathetic activity and cortisol responses to stress. C_LIO_LIThese results suggest a dietary strategy to increase stress resilience. C_LI

physiology↗

bioRxiv2020

Diet, psychosocial stress, and Alzheimer's disease-related neuroanatomy in female nonhuman primates

INTRODUCTIONAssociations between diet, psychosocial stress, and neurodegenerative disease, including Alzheimers disease (AD), have been reported, but causal relationships are difficult to determine in human studies. METHODSWe used structural magnetic resonance imaging in a well-validated nonhuman primate model of AD-like neuropathology to examine the longitudinal effects of diet (Mediterranean versus Western) and social subordination stress on brain anatomy, including global volumes, cortical thicknesses and volumes, and twenty individual regions of interest (ROIs). RESULTSWestern diet resulted in greater cortical thicknesses, total brain volumes and gray matter, and diminished cerebrospinal fluid and white matter volumes. Socially stressed subordinates had smaller whole brain volumes but larger ROIs relevant to AD than dominants. DISCUSSIONThe observation of increased size of AD-related brain areas is consistent with similar reports of mid-life volume increases predicting increased AD risk later in life. While the biological mechanisms underlying the findings require future investigation, these observations suggest that Western diet and psychosocial stress instigate pathologic changes that increase risk of AD-associated neuropathologies, whereas Mediterranean diet may protect the brain. RESEARCH IN CONTEXTO_LISystematic review: The authors reviewed the literature with PubMed and Google Scholar and found a number of publications which are cited that suggest that AD pathogenesis begins well before the onset of symptoms. C_LIO_LIInterpretation: Our findings support the hypothesis that Western diet and psychosocial stress may instigate neuroinflammatory responses that increase risk of later developing AD-like neuropathologies, whereas the structural stasis in the Mediterranean diet group may represent a resilient phenotype. C_LIO_LIFuture directions: The manuscript serves as a critical first step in describing risk and resilient phenotypes during middle age in a nonhuman primate model of AD-like neuropathology. This report lays the groundwork for ongoing efforts to determine whether neuroinflammatory profiles differed across diet and stress groups. Future studies should aim to understand the temporal emergence of functional disparities associated with the changes in brain structure observed here. C_LI HIGHLIGHTSO_LIGlobal brain volumes changed in response to Western, but not Mediterranean, diet. C_LIO_LIWestern diet increased cortical thickness in multiple regions relevant to AD. C_LIO_LIMediterranean diet did not alter cortical thicknesses relevant to AD. C_LIO_LIBrain regions associated with AD risk differed between low and high stress monkeys. C_LIO_LIPsychosocial stress may modulate the effects of diet on the brain. C_LI

neuroscience↗