Poster #14 - Differential Susceptibility is Age-Dependent: 5-HTTLPR x Maternal Warmth Effects on Conduct Problems in Ages 3-11

• In Event: 2-055 - Poster Session 06
  In Poster Session: PS 06 Section - Biological Processes: Neuroscience and Genetics

Integrative Statement

The Differential Susceptibility hypothesis (Ellis, Boyce, Belsky, Bakermans-Kranenburg, & van Ijzendoorn, 2011) proposes that individuals differ in the degree they are influenced by both negative and positive aspects of the environment, for better and for worse. This susceptibility is based, in part, on their genetic makeup. However, most studies in the field measure the environment and the behavioral outcome in a single time point, or at best a few years apart. Therefore, little is known about the development of susceptibility across the life span (Ellis et al., 2011). Thus, the question arises: what is the developmental trajectory of the differential susceptibility pattern – is it constant throughout life or perhaps there are susceptible periods? As the human brain has critical periods of development especially in the early years of life (Chugani, 1998), we hypothesized that differential susceptibility would be more prominent in childhood, at least when it comes to rearing influences. A first study to test the developmental path of differential susceptibility found a significant interaction between the DRD4 gene and sensitive parenting on externalizing behavior at ages 18 and 36 months, but not at 48 months and 5 years (Windhorst et al., 2014). This might support the notion of early susceptible periods. However, there is still a need to take a broader perspective on development. The current study used Linear Mixed Effects Models to investigate whether the previously shown interaction between the 5-HTTLPR gene and parenting on conduct problems (e.g., Brett et al., 2015) changes between ages 3 to 11 (N = 1254). Mothers reported on their maternal warmth and on their children’s conduct problems through home questionnaires or when visiting the lab, at ages 3, 5, 9, and 11. DNA samples were available for between 579 and 995 children, depending on age sample. Using the nlme package (Pinheiro, Bates, DebRoy, Sarkar and R Core Team, 2018) in R (R Core Team, 2018), we estimated a model of a 3-way interaction between 5-HTTLPR, maternal warmth and time in predicting conduct problems, to test whether the GxE interaction changes through time. The model also included the three main effects and three 2-way interactions. The full model information and results can be seen in Table 1. According to hypothesis, we found a 3-way interaction, suggesting that the differential susceptibility pattern changes throughout time. As can be seen in Figure 1, the interaction pattern changes between the ages, when the only age showing an interaction pattern is age 3. This was also tested with a regression analysis for each age separately, when only age 3 showed a significant interaction. This interaction was consistent with the differential susceptibility model (according to Roisman et al., 2012). Furthermore, we found a negative effect of maternal warmth and time on conduct problems and of 5-HTTLPR x maternal warmth on conduct problems. These findings emphasize the importance of a developmental perspective when examining influences of differential susceptibility on human development, and the importance of these processes in the early years, but perhaps not as much later in life.

Authors

• Noam Markovitch, The Hebrew University of Jerusalem
  Non-Presenting Author

• Ariel Knafo-Noam, Hebrew University of Jerusalem
  Presenting Author