Dietary Saturated Fat Intake Moderates the Effect of Plasma Triglycerides on Memory Performance in Middle-Aged Adults

Isabelle Gallagher,1 Yanrong Li,1 Cherry Youn,1 Hirofumi Tanaka,2 Jaimie N Davis,3 Andreana P Haley1 1Department of Psychology, University of Texas at Austin, Austin, TX, USA; 2Cardiovascular Aging Research Laboratory, Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, USA; 3Department of Nutritional Sciences, The University of Texas at Austin, Austin, TX, USACorrespondence: Andreana P Haley, Department of Psychology, The University of Texas at Austin, SEA 3.130E, 108 E Dean Keeton St, Austin, TX, 78712, USA, Tel +1 512 232 0863, Fax +1 512 471-6175, Email haley@austin.utexas.eduPurpose: With Alzheimer’s disease and related dementias are projected to triple by 2050, addressing modifiable health and lifestyle factors is crucial to prevention and reducing the associated public health burden. This study investigates the interaction between triglyceride levels and dietary fat intake and diet quality on memory performance in middle-aged adults at heightened risk for metabolic health issues.Patients and Methods: Community-dwelling adults aged 40– 65 with cardiometabolic health risks participated in this cross-sectional study. Participants with a history of neurological or psychiatric conditions were excluded. Dietary intake was self-reported through a 3-day food record, and serum triglyceride levels were measured. Neuropsychological testing assessed memory performance. Cross-sectional regression analyses examined how dietary fat intake and quality interact with triglyceride levels to affect memory performance in 146 adults.Results: The analysis revealed a significant interaction between triglyceride levels and the ratio of dietary saturated fat to total caloric intake on memory performance (β = − 0.087, p = 0.022). The relationship between triglyceride levels and memory performance was modified by the ratio of saturated fat to total caloric intake. At higher levels of saturated fat intake, higher triglycerides were associated with worse memory performance. However, at lower levels of saturated fat intake, the association between triglycerides and memory performance was not statistically significant. Better adherence to USDA dietary guidelines, reflected by higher Healthy Eating Index 2020 scores, was associated with better memory performance (β = 0.018, p < 0.002), regardless of triglyceride levels.Conclusion: Diet quality, as indicated by adherence to dietary guidelines, supports cognitive health. Elevated triglycerides combined with a high ratio of dietary saturated fat intake were associated with poorer memory performance. Precision nutrition strategies aimed at reducing saturated fat intake in midlife adults with elevated triglyceride levels may help mitigate memory-related cognitive decline and enhance brain health.Plain Language Summary: This study explored how diet and triglyceride levels (a type of fat in the blood) might influence memory and the risk of Alzheimer’s disease and other dementias in adults at higher risk. We focused on middle-aged adults (ages 40-65) who had cardiometabolic health issues, such as obesity, high blood pressure, high cholesterol, or diabetes. We worked with 146 adults from the community who reported their eating habits over three days and took tests to measure triglyceride levels and memory performance. The study found that higher triglyceride levels combined with a diet high in saturated fats (common in many Western diets) were linked to poorer memory performance. However, adults with high triglycerides who ate less saturated fat performed better on memory tests than those with higher saturated fat intake. Overall, following a healthier diet was associated with better memory, regardless of triglyceride levels. These findings suggest that improving diet quality—by adhering to dietary guidelines—could help protect brain health and reduce memory problems. For people with high triglycerides, cutting back on saturated fat may help improve memory and protect against cognitive decline. These results point to the importance of personalized nutrition strategies to support brain health and potentially reduce the risk of memory loss as we age.Keywords: cardiometabolic, Western diet, cognition, midlife