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Prefrontal Cortex Structure Mediates the Relationship between Plasma Phospholipid Stearidonic Acid and Fluid Intelligence in Healthy, Older Adults
Author(s) -
Zamroziewicz Marta K.,
Paul Erick J.,
Zwilling Chris E.,
Das Tapas,
Pereira Suzette,
Barbey Aron K.
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.460.1
Subject(s) - polyunsaturated fatty acid , prefrontal cortex , phospholipid , fatty acid , cognition , chemistry , psychology , biochemistry , neuroscience , membrane
Accumulating evidence indicates that omega‐3 (n‐3) polyunsaturated fatty acids (PUFA) have a beneficial effect on brain aging. However, the core facets of cognition and the brain structures upon which particular n‐3 PUFA may act are unknown. This study investigated the neural structures that mediate the effect of stearidonic acid (18:4n‐3; SDA) on general fluid intelligence (Gf), a cognitive ability that allows for adaptive problem solving in novel situations and declines steadily in healthy aging. SDA is a long‐chain n‐3 PUFA that can originate from dietary plant oils and seeds or from desaturation of its precursor n‐3 PUFA. Prior evidence suggests that (i) SDA is an efficient precursor of very‐long‐chain n‐3 PUFA, (ii) higher levels of very‐long‐chain n‐3 PUFA are linked to enhanced Gf as well as prefrontal cortex (PFC) structure, and (iii) PFC structure impacts Gf. Therefore, we hypothesized that higher levels of SDA are associated with better Gf, and that this relationship is mediated by PFC gray matter structure. We examined 99 cognitively intact adults between the ages of 65 and 75 to investigate the relationship between levels of SDA (measured by plasma phospholipid fatty acid analysis), tests of Gf (measured by the Wechsler Abbreviated Scale of Intelligence), and gray matter volume of the PFC and its constituent regions (measured by the Freesurfer imaging analysis suite). A mediation model was used to characterize the relationship between SDA levels, PFC gray matter volumes, and Gf, controlling for age, sex, education, income, and total intracranial volume. The mediation analysis revealed that total gray matter volume of the PFC fully mediates the relationship between SDA and Gf. First, higher SDA levels were related to greater total PFC gray matter volume (p=0.027; path a). Second, higher SDA levels were linked to better Gf (p=0.012; path c). The indirect pathway of mediation (i.e., the effect of SDA levels through total PFC gray matter volume on Gf) was statistically significant (p=0.019; path a–b). The direct pathway of mediation (i.e., the effect of SDA levels directly on Gf, accounting for the effect of total PFC gray matter volume) was not statistically significant (p=0.053; path c'). Therefore, total PFC gray matter volume fully mediated the relationship between SDA levels and Gf. These results contribute to a line of evidence suggesting that particular nutrients may slow or prevent age‐related cognitive decline by influencing specific structures within the brain. The individual relationships reported within the mediation, including those between n‐3 PUFA and Gf, between n‐3 PUFA and PFC structure, and between the PFC structure and Gf, are substantiated by prior findings. This report provides a novel structural mediation between an n‐3 PUFA and Gf. Future work should examine the potential mechanisms underlying this mediation, including SDA‐enhanced neuronal membrane integrity, inflammatory status, antioxidant status, and energy metabolism within the PFC. Support or Funding Information Supported by Abbott Nutrition through the Center for Nutrition, Learning, and Memory.Totally gray matter volume of the prefrontal cortex fully mediated the relationship between stearidonic acid levels and fluid intelligence.