Parental psychopathology in families of children with attention‐deficit/hyperactivity disorder and exposed to maternal smoking during pregnancy

Background Both genetic and environmental factors have been implicated in the etiology of attention‐deficit/hyperactivity disorder ( ADHD ). We had previously suggested that exposure to maternal smoking during pregnancy ( MSDP ) may be a valid basis for delineating a distinct subtype of ADHD , where children exposed to MSDP present with a more severe clinical picture. Here, we examine the psychopathology of parents in this group, to better understand the etiology of ADHD . Methods Using the Family Interview for Genetic Studies in a sample of 514 families of children with ADHD , we collected data pertaining to lifetime parental psychopathology. Families were stratified based on maternal smoking during the complete gestational period. The frequency of different disorders was compared using the χ 2 statistic. Results In the group where mothers smoked during pregnancy, both parents were significantly more likely to have antisocial personality disorder, and problems with alcohol and drug abuse. Mothers had a significantly higher frequency of major depressive disorder ( MDD ), while fathers showed a trend for both MDD and bipolar disorder. Conclusions Based on the pattern of psychopathology in parents of children exposed to MSDP , as well as earlier reports of the severe clinical, behavioral, and cognitive phenotype in these children, combined with the large body of epidemiological evidence, we propose that these children present a distinct subtype of ADHD with comorbid conduct disorder. Furthermore, we propose that MSDP may be a proxy measure to help delineate this subtype.