Linking extremely low birth weight and internalizing behaviors in adult survivors: Influences of neuroendocrine dysregulation.

Young adult survivors of extremely low birth weight (ELBW; <1000 g) are known to be at elevated risk for internalizing problems, though little is known about the mechanisms that may lead to higher levels of psychopathology in this vulnerable group. We examined the moderating influence of neuroendocrine functioning on the link between being born at ELBW and internalizing behaviors at age 30-35. Salivary cortisol was collected 20 min after completion of a social stress task in 83 ELBW adult survivors and 89 normal birth weight (NBW; >2500 g) controls. Using a median split, participants were separated into two groups (high or low afternoon cortisol levels). ELBW survivors with "high" afternoon cortisol levels self-reported significantly higher levels of internalizing behaviors compared to those with "low" afternoon cortisol levels. This association between afternoon cortisol and internalizing symptoms did not exist among NBW controls. These results are suggestive of a differential susceptibility for internalizing behaviors among ELBW survivors, depending on their ability to regulate neuroendocrine responses.