Christopher James Machle

Adolescence is an important period for the development of mentalizing and self-referential processing, and a period of increased risk for internalizing disorders such as anxiety and depression. However, the relationships between these processes, particularly in adolescents’ daily lives, remain unclear. In this intensive longitudinal study, we investigate the relationship between two dimensions of self-referential mentalizing (SRM)—1) engagement in SRM, and 2) negativity of SRM—as well as their interaction, in relation to internalizing feelings and symptoms. 149 adolescent females (M = 16.26 years, Range = 13.83 to 20.38 years) completed one or more (M = 2.0 bursts completed per participant) 30-day diary bursts where they answered daily questions about 1) engagement in and 2) negativity of self-referential mentalizing (SRM) and daily feelings of anxiety and depression. They also completed questionnaires measuring severity of internalizing symptoms once at each burst. Using Dynamic Structural Equation Modeling (DSEM), we find that, at the between-person level, while both SRM and negative SRM were associated with feelings of depression and anxiety, only negative SRM was significantly positively associated with feelings of depression and anxiety after controlling for SRM. Individual differences in SRM and negative SRM were also associated with psychiatric measures of generalized anxiety, overall anxiety, and depression. At the daily, within-person level, experiencing elevated SRM and negative SRM on a given day was associated with elevated feelings of anxiety and depression on that same day. Additionally, there was a significant interaction at the daily, within-person level such that daily SRM was more strongly associated with daily feelings of anxiety and depression when the content of that SRM was negative. Together, our findings suggest that negative SRM, in particular, may be key for understanding associations with overall feelings of depression/anxiety, as well as changes in daily affect at the within-person level. While SRM and feelings of depression and anxiety covary on a day-to-day basis, the strength of this daily coupling was largely unrelated to severity of internalizing symptoms, suggesting that these daily dynamics may represent normative, rather than clinical, processes—at least for female adolescents. Together, our findings highlight the importance of considering multiple dimensions of SRM jointly, with the negativity of SRM emerging as particularly important for understanding internalizing affect at both the between- and within-person level.

Growing evidence indicates that human milk oligosaccharides (HMOs) are important bioactive compounds that enhance health and developmental outcomes in breastfed babies. Maternal dietary intake likely contributes to variation in HMO composition, but studies identifying diet–HMO relationships are few and inconsistent. This study aimed to investigate how the maternal intake of macronutrients and micronutrients—specifically proteins, fats, vitamins, and minerals—associated with HMOs at 1 month (n = 210), 6 months (n = 131), and 12 months postpartum (n = 84). Several associations between maternal dietary factors and HMO profiles were identified utilizing partial correlation analysis. For example, maternal free sugar (rho = −0.02, p < 0.01), added sugar (rho = −0.22, p < 0.01), and sugary sweetened beverage (rho = −0.22, p < 0.01) intake were negatively correlated with the most abundant HMO, 2′-fucosyllactose (2′-FL), at 1 month, suggesting that higher sugar consumption was associated with reduced levels of 2′-FL. Further, vitamins D, C, K, and the minerals zinc and potassium were positively correlated with 2′-FL at 1 month (p_All < 0.05). For the longitudinal analysis, a mixed-effects linear regression model revealed significant associations between maternal vitamin intake and HMO profiles over time. For example, for each unit increase in niacin intake, there was a 31.355 nmol/mL increase in 2′-FL concentration (p = 0.03). Overall, the results provide additional evidence supporting a role for maternal nutrition in shaping HMO profiles, which may inform future intervention strategies with the potential of improving infant growth and development through optimal HMO levels in mothers’ milk.