At-a-Glance

Genes associated with ADHD, autism, and schizophrenia may also affect prenatal factors such as maternal depression and anxiety during pregnancy, highlighting the need to consider genetic factors when studying effects of the prenatal environment on brain development.

Background: Numerous studies have investigated how maternal behavior and health during pregnancy relate to the development of attention deficit/hyperactivity disorder (ADHD), ASD, and schizophrenia, but it remains uncertain whether prenatal exposures directly cause these conditions or if they are influenced by shared genetic factors. One way to explore this is to examine whether mothers with genetic predisposition for ADHD, ASD, or schizophrenia are also more likely to be exposed to pregnancy-related factors that are associated with those conditions, which would imply that prenatal factors alone may not be the sole cause ADHD, ASD, or schizophrenia.

Methods & Findings: This study included genetic, lifestyle, and health data from 14,539 mothers who participated in a Norwegian pregnancy study. Researchers examined the relationship between mothers’ genetic predisposition for ADHD, ASD, and schizophrenia and certain factors that were present during pregnancy. Higher likelihood of maternal anxiety or depression during pregnancy was associated with genetic predispositions for schizophrenia, ADHD, and ASD. Genetic predisposition for ASD was not significantly associated with other prenatal factors. However, mothers with genetic predispositions for either ADHD or schizophrenia were more likely to smoke and gained more weight during pregnancy. Mothers with a genetic predisposition for ADHD were also more likely to be younger and more likely not to take supplements during pregnancy, while mothers with a genetic predisposition for schizophrenia were more likely to drink coffee during pregnancy.

Implications: The results of this study suggested that maternal genetic predispositions for ADHD, ASD, and schizophrenia are associated with certain factors such as depression and anxiety during pregnancy. These shared genetic predispositions imply that the prenatal exposures alone likely do not cause these neurodevelopmental conditions. Additional research is needed to understand which exposures during pregnancy may impact children’s developmental outcomes, taking into account any shared genetic predisposition of the mother. Studies that fail to consider genetic factors for different conditions may lead researchers to draw false conclusions about the effects of environmental exposures on child brain development.