Examining the Effects of a High Fat, High Sugar Diet in Adolescence on Memory and Executive Functioning in Young Adulthood

Abstract

Accumulating evidence from animal studies suggests that diets high in fats and sugar lead to poorer cognitive functioning. Importantly, animals exposed to a high fat, high sugar (HFHS) diet during adolescence show more pronounced deficits in cognitive performance than animals given this diet during adulthood, suggesting an age-specific vulnerability for diet-induced cognitive impairments. Given that the three primary sources of daily caloric intake for children and adolescents in the United States are dessert, pizza, and soda, translational research is needed to better understand the link between diet during development and cognitive function. Some studies demonstrate long-term effects of adolescent exposure to HFHS diets, highlighting a need for longitudinal research in this area. The current study sought to investigate whether unhealthy dietary habits during adolescent development predicts performance on tasks of memory and executive function using publicly available data from the National Longitudinal Study of Adolescent to Adult Health (Add Health study). Using three separate linear regressions, we tested whether HFHS intake in adolescence predicts memory and executive function in young adulthood using the following outcomes as dependent variables: total word recall score (immediate trial), total word recall score (delayed trial), and total number recall score. We also tested whether a robust indicator of inflammation, high-sensitivity C-reactive protein (hsCRP), which was measured in adulthood, mediates the relationship between HFHS intake in adolescence and cognitive performance in adulthood. Finally, we tested whether physical activity in adolescence moderates the relationship between HFHS intake in adolescence and hsCRP as well as cognitive performance in adulthood. The results of the regression analyses reveal that HFHS scores in adolescence significantly and negatively predict performance on both the immediate and delayed word recall trials in adulthood, even after controlling for relevant covariates such as SES and BMI. The effect of HFHS scores on number recall scores was trending toward significance. The relationship between diet and memory was mediated by hsCRP, though HFHS scores was negatively associated with hsCRP. Physical activity did not moderate the effect of diet on hsCRP or cognitive performance. These findings support animal and human studies showing a relationship between HFHS intake and poorer cognitive performance. Importantly, the results of the current study extend the existing literature by suggesting that HFHS intake during adolescent development may affect cognitive performance later in life. Replication of this study is needed along with further research to identify possible physiological mechanisms underlying the relationship between HFHS and cognition as well as factors that modify this relationship.