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Research examining the role of carbohydrates in postprandial cognition has yielded inconsistent results. Some studies demonstrate significant cognitive improvement following caloric intake, while others do not. Interindividual differences in glucoregulation partially explain this inconsistency. Prior work suggested persons with artificially dichotomized “better” glucoregulation perform best after caloric intake with more carbohydrates, while individuals with “poorer” glucoregulation perform best after lower carbohydrate intake. Recent works utilizing more rigorous statistical methodology (i.e., continuous measures of glucoregulation and linear mixed modeling) imply the role of glucoregulation in postprandial cognition might vary by cognitive domain. However, these studies examined young adults and children, and considered only fasting blood glucose. Work in animal models indicates the role of glucoregulation in postprandial cognition may vary by age, and it may also differ based on how it is measured. The current study examined the role of glucoregulation in postprandial cognition among adults using multiple glucoregulation indices (including fasting plasma glucose and response to a glucose excursion challenge) across three ecologically valid beverage conditions. It was hypothesized that participants with poorer glucoregulation would demonstrate better cognitive response following low-carbohydrate beverages, with the opposite pattern occurring for participants with better glucoregulation. Differences in these relationships across cognitive domains and glucoregulation indices were also examined. Healthy, overnight-fasted adults (n=44) attended three morning sessions in a randomized, counterbalanced, repeated-measures design. After baseline cognitive testing (CNS Vital Signs) and blood draw, participants ingested 8oz of 2% milk, apple juice, or water. Re-testing occurred 30, 90, and 150 min post-ingestion. Complex attention, working memory, processing speed, executive functioning, and simple attention composite scores from the CNS Vital Signs test battery were analyzed using linear mixed modeling. Results showed partial support for study hypotheses. At 30 minutes, participants with higher fasting glucose showed better complex attention scores after ingesting milk or water compared to juice, and milk facilitated processing speed and executive function compared to water for participants with larger glucose responses. These relationships reversed at 150 minutes. There were no findings that suggested juice was beneficial or detrimental for performance based on glucose response. The role of glucoregulation in postprandial cognition among adults varies based on the aspect of glucoregulation in question, as well as cognitive domain. Replication using an oral glucose tolerance test to measure glucose response, as well as cognitive measures that incorporate both speed and accuracy, is recommended for future research. |
