Adverse family life events during pregnancy and ADHD symptoms in five year old offspring

Adverse life events during pregnancy have been suggested to increase the risk of ADHD in the offspring, but the role of familiar confounding is unclear. The aim of this study was to clarify if prenatal exposure to adverse life... [ view full abstract ]

Adverse life events during pregnancy have been suggested to increase the risk of ADHD in the offspring, but the role of familiar confounding is unclear. The aim of this study was to clarify if prenatal exposure to adverse life events in the family is associated with ADHD symptoms in five year old children, and to assess if such an association remains after controlling for shared familial factors. The study is based on 34,751 children (including 6,427 siblings) whose mothers participated in the population-based Norwegian Mother and Child Cohort Study during pregnancy and at the child’s age of five. During pregnancy, mothers reported whether they had experienced eight specific life events. ADHD symptoms were reported by parents at the child’s age of five using the Conner’s Parent Rating Scale –Revised: short form. Linear regression models were used to assess mean ADHD scores (range: 0-3) in the full cohort. To adjust for unmeasured familial confounding, fixed-effect models were used to compare mean ADHD scores among exposure-discordant siblings. Results showed that children exposed to adverse life events had higher ADHD scores at age five. The strongest effect was observed for financial problems, and the weakest for having lost someone close (mean differences 0.10 [95% CI 0.09-0.11] and 0.02 [95% CI 0.01-0.04] respectively in adjusted models). Comparing exposure-discordant siblings resulted in attenuated estimates that were no longer statistically significant (e.g. mean difference for financial problems -0.03 [95% CI -0.07-0.02]). However, wide confidence intervals for specific life events hamper full interpretation of these results. These findings show that prenatal exposure to adverse life events in the family is associated with ADHD symptoms in five year old children, but most associations seem to be explained by familial confounding.