There is now a clear focus on incorporating, and integrating, multiple levels of analysis in developmental science. The current study adds to research in this area by including markers of the immune and neuroendocrine systems in a longitudinal study of temperament in infants. Observational and parent-reported ratings of infant temperament, serum markers of the innate immune system, and cortisol reactivity from repeated salivary collections were examined in a sample of 123 infants who were assessed at 6 months and again when they were, on average, 17 months old. Blood from venipuncture was collected for analyses of nine select innate immune cytokines; salivary cortisol collected prior to and 15 min and 30 min following a physical exam including blood draw was used as an index of neuroendocrine functioning. Analyses indicated fairly minimal significant associations between biological markers and temperament at 6 months. However, by 17 months of age, we found reliable and nonoverlapping associations between observed fearful temperament and biological markers of the immune and neuroendocrine systems. The findings provide some of the earliest evidence of robust biological correlates of fear behavior with the immune system, and identify possible immune and neuroendocrine mechanisms for understanding the origins of behavioral development.
Bibliographical noteFunding Information:
We thank Suzanne Coglitore, Carol Ferro, Mary Harper, Bridget O'Connor, Bridget Szczypinski, and the staff at the Clinical Research Center for their assistance with the study, and the mothers and babies who participated. The Thoughts, Emotions, and Mood in Pregnancy study was funded by National Institute of Health Grant MH073019; support was also provided by NIH Grants MH529173, K23MH080290, and K99HD070953. Additional support was provided through the Clinical Research Center from UL1 RR 024160 from the National Center for Research Resources, a component of the NIH, and the NIH Roadmap for Medical Research.