Key Points
This study sought to determine the mechanisms which could account for the observation that lower amounts of omega-3s are correlated with declines in fluid intelligence in older people. Blood levels of six different omega-3s in 122 ‘cognitively intact’ subjects ranging from 65 to 75 years of age were assessed. The omega-3s measured were ALA, SDA (steriodonic acid), ETE (eicosatrienoic acid), EPA, DHA and DPA. The structural integrity of the frontoparietal cortex structure within the brain was assessed. Fluid intelligence is the ability of the brain to cope with new, novel situations via a process of inductive and deductive reasoning and has been linked with the frontoparietal cortex (FPC) region of the brain. A decline in fluid intelligence has been identified as one of the most debilitating aspects of dementia in older adults. Here, higher levels of ALA, SDA and ETE, corresponded to stronger FPC structure, and fluid intelligence. Better fluid intelligence was predicted by higher levels of SDA, ALA and ETE, which is a metabolite of SDA. Future research would need to look at whether the precursors are neuroprotective.
ABSTRACT
INTRODUCTION: Accumulating evidence indicates that cognitive decline depends not only upon changes in brain health, but critically, also upon nutritional status. Decline in fluid intelligence, one of the most debilitating aspects of cognitive aging, has been linked to omega-3 polyunsaturated fatty acid (PUFA) status; however, it is not known whether this phenomenon results from specific omega-3 PUFAs acting on particular aspects of brain health. Therefore, this study aims to explore whether particular patterns of omega-3 PUFAs influence fluid intelligence by supporting specific neural structures. METHODS: We measured six plasma phospholipid omega-3 PUFAs, fluid intelligence, and regional gray matter volume in the frontal and parietal cortices in 100 cognitively intact older adults (65-75 years old). A four-step mediation analysis was implemented using principal component analysis and multivariate linear regressions, adjusted for age, gender, education, and body mass index. RESULTS: The mediation analysis revealed that one pattern of omega-3 PUFAs, consisting of alpha-linolenic acid, stearidonic acid, and eicosatrienoic acid, was linked to fluid intelligence, and that total gray matter volume of the left frontoparietal cortex (FPC) fully mediated the relationship between this omega-3 PUFA pattern and fluid intelligence. DISCUSSION: These data demonstrate that fluid intelligence may be optimally supported by specific omega-3 PUFAs through preservation of FPC gray matter structure in cognitively intact older adults. This report provides novel evidence for the benefits of particular omega-3 PUFA patterns on fluid intelligence and underlying gray matter structure.
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