A latent State Trait Model of Cortisol in NormallyDeveloping Youth

Research relating salivary cortisol levels with internalizing and externalizing behavior problems in youth has yielded inconsistent results, likely due to the high day-to-day variation in stress regulation. Understanding stability in this changing system may require an analytical strategy that separates variance in cortisol levels attributable to trait- or "basal" versus state- or "situationally-specific¿ sources. Early morning saliva samples were obtained from 654 youth (range 6-16 yrs ) on two successive days one year apart. Latent state trait modeling revealed that 70% of the variance in cortisol levels could be attributed to state-like sources, and 28% to trait-like sources. Higher levels of externalizing problems were consistently associated with lower basal cortisol in boys. This finding is consistent with studies of at-risk and clinical groups. The present findings confirm the relationship spans both normative and atypical child development, and supports speculations that boys with low cortisol may be at risk for externalizing behavior problems.