Lectures and seminars Bridging the Gap between Sensitive Period Research and Causal Methods
Henning Tiemeier, Professor of Social and Behavioral Science and the Sumner and Esther Feldberg Chair in Maternal and Child Health at the Harvard T.H. Chan School of Public Health, Boston.
Bridging the Gap between Sensitive Period Research and Causal Methods: Exposure to Screen Time Use and High Body Mass Index in Children
This talk will introduce a new framework for sensitive periods based on a causal inference approach from epidemiology. Sensitive period refers to the timing during which an exposure to specific experiences has a particularly strong impact on a specific outcome later in life. Importantly, effects during sensitive periods can be modified by later exposures.
I will illustrate this concept with two empirical examples of interest: first, associations of screen time with body mass index (BMI), leveraging 10 repeated exposure and outcome assessments from ages 1 to 10 years from the prospective GUSTO cohort (1,030 children); second associations of BMI with clinician rated puberty onset using a cohort of 132,452 children born between 2003 and 2011 in Northern California and followed through 2023. G-estimation of structural nested mean modeling and g-formula were used to estimate period specific and average treatment effects while accounting for both feedback between chained exposures and for time-varying confounders. Latent effects and sensitive period effects were explored. In the first study, we demonstrated a modest average effect of screen time on boys’ body mass across childhood across ages. However, we found no support for any sensitive period effect of screen time exposure on the body mass development in boys or girls. In the second study we showed there is only a negligible effect of BMI before age 6 years on puberty onset in both boys and girls. Counterfactual outcomes for realistic screen time policy implementations or overweight management are discussed.
I will also explain the importance of considering chained exposure, latent effects, and time-varying confounders by utilizing repeated exposure and outcome measurements to accurately identify the causal effects of sensitive periods.
Presentation of speaker
Henning Tiemeier is a psychiatric epidemiologist who studies child development in population-based cohort studies. His work has a focus on early life exposures such as maternal depression and poor thyroid function. Much of his work takes a neurodevelopmental approach and his group conducted large scale brain imaging studies in children and adolescents. Recent work shows how parenting and environmental risk factors relate to brain development in childhood and pre-adolescence. Other studies highlight methodological problems in child and adolescent psychiatric research using multi-informant assessments or causal inference approaches. His multidisciplinary work combining epidemiology, genetics, brain imaging, and child development bridges historically separate disciplines and forms Population Neuroscience.
At Harvard Chan he has received NIH funding to establish the Mississippi Delta Center of Excellence in Maternal Health and conduct observational studies and trials to improve maternal morbidity, and also works on a longitudinal study of children of incarcerated mothers. Tiemeier has received several honors among which the 2017 Dutch VICI prize, the 2019 Leon Eisenberg Award, and the 2023 Alzheimer Award.
Host of seminar: Professor Fang Fang, Institute of Environmental Medicine