Risk factors for the childhood development of co-occurring internalizing and externalizing symptoms are not well understood, despite a high prevalence and poor clinical outcomes associated with this co-occurring phenotype. We examined inherited and environmental risk factors for co-occurring symptoms in a sample of children adopted at birth and their birth mothers and adoptive mothers (N = 293). Inherited risk factors (i.e., birth mothers' processing speed and internalizing symptoms) and environmental risk factors (i.e., adoptive mothers' processing speed, internalizing symptoms, and uninvolved parenting) were examined as predictors for the development of internalizing-only, externalizing-only, or co-occurring symptoms using structural equation modeling. Results suggested a unique pattern of predictive factors for the co-occurring phenotype, with risk conferred by adoptive mothers' uninvolved parenting, birth mothers' slower processing speed, and the birth mothers' slower processing speed in tandem with adoptive mothers' higher internalizing symptoms. Additional analyses indicated that when co-occurring-symptom children were incorporated into internalizing and externalizing symptom groups, differential risk factors for externalizing and internalizing symptoms emerged. The findings suggest that spurious results may be found when children with co-occurring symptoms are not examined as a unique phenotypic group.
Bibliographical noteFunding Information:
This project was supported by Grant R01 HD042608 from NICHD, NIDA, and OBSSR, NIH, US PHS (Principal investigator [PI] years 1-5: D.R.; PI years 6-10: L.D.L.); Grant R01 MH092118 from NIMH, NIH, US PHS (to J.M.N. and L.D.L.); Grant R01 DA020585 from NIDA, NIMH and OBSSR, NIH, US PHS (to J.M.N.); and Grant P50 DA035763 from NIDA, NIH, US PHS (to Patricia Chamberlain and P.A.F.). The content is solely the responsibility of the authors and does not necessarily represent the official views of the Eunice Kennedy Shriver NICHD or the NIH. We thank the birth parents and adoptive families who participated in this study and the adoption agencies who helped with the recruitment of study participants. We gratefully acknowledge Rand Conger, John Reid, Xiaojia Ge, Jody Ganiban, and Laura Scaramella for their contributions to the larger study.
© Cambridge University Press 2015.
All Science Journal Classification (ASJC) codes
- Developmental and Educational Psychology
- Psychiatry and Mental health