Spontaneous infant crying modulates vagal activity in real time.

Porges' polyvagal theory (1991) proposes that the activity of the vagal nerve modulates moment-by-moment changes in adaptive behavior during stress. However, most work, including research with infants, has only examined vagal changes at low temporal resolutions, averaging 30+ s across phases of structured stressor paradigms. Thus, the true timescale of vagal regulation-and the extent to which it can be observed during unprompted crying-is unknown. The current study utilized a recently validated method to calculate respiratory sinus arrhythmia (RSA) dynamically at a high resolution of 5 Hz (updated every 200 ms) in a home-based infant study. Using an event-related analysis, we calculated the relative change in RSA around the onset of naturally occurring unprompted instances of n = 41 infants' 180 crying events. As predicted, RSA significantly decreased after the onset of crying compared to non-crying chance changes in RSA. Decreasing trends in RSA were driven by infants with higher pre-cry RSA values, infants rated lower in Negative Affectivity, and those rated both high and low in Orienting by their mothers. Our results display the timescale of RSA in spontaneous and naturalistic episodes of infant crying and that these dynamic RSA patterns are aligned with real-time levels of RSA and also caregiver-reported temperament.

High-Normal Adolescent Fasting Plasma Glucose Is Associated With Poorer Midlife Brain Health: Bogalusa Heart Study.

CONTEXT: It is unclear how adolescent glycemic status relates to brain health in adulthood. OBJECTIVE: To assess the association between adolescent fasting plasma glucose (FPG) and MRI-based brain measures in midlife. DESIGN: Between 1973 and 1992, the Bogalusa Heart Study (BHS) collected FPG from children, 3 to 18 years old, and followed up between 1992 and 2018. Cognitive tests and brain MRI were collected in 2013 to 2016 and 2018. SETTING: Observational longitudinal cohort study. PARTICIPANTS: Of 1298 contacted BHS participants, 74 completed screening, and 50 completed MRI. MAIN OUTCOME MEASURES: Mean FPG per participant at ages <20, 20 to 40, and over 40 years old; brain white matter hyperintensity (WMH) volume, gray matter volume, and functional MRI (fMRI) activation to a Stroop task; tests of logical and working memory, executive function, and semantic fluency. RESULTS: At MRI, participants were middle aged (51.3 ± 4.4 years) and predominantly female (74%) and white (74%). Mean FPG was impaired for zero, two, and nine participants in pre-20, 20 to 40, and over-40 periods. The pre-20 mean FPG above the pre-20 median value (i.e., above 83.5 mg/dL) was associated with greater WMH volume [mean difference: 0.029% of total cranial volume, CI: (0.0059, 0.052), P = 0.015] and less fMRI activation [-1.41 units (-2.78, -0.05), P = 0.043] on midlife MRI compared with below-median mean FPG. In controlling for over-40 mean FPG status did not substantially modify the associations. Cognitive scores did not differ by pre-20 mean FPG. CONCLUSIONS: High-normal adolescent FPG may be associated with preclinical brain changes in midlife.