Are family variables associated with ADHD, inattentive type? A case-control study in schools.

Attention-deficit/hyperactivity disorder (ADHD) seems to be associated with significant psychosocial adversity. However, few studies assessed the role of environmental, social and interpersonal factors specifically in ADHD, inattentive type (ADHD-I). Thus, this study aims to investigate whether family environment risk factors are associated with ADHD-I. In a case-control study, we assessed a non-referred sample of 100 children and adolescents with ADHD-I and 100 non-ADHD controls (6-18 years old). They were systematically evaluated through structured diagnostic interviews. The following family adversity measures were used: Rutter's family adversity index (marital discord, low social class, large family size, paternal criminality, maternal mental disorder), Family Environment Scale (FES) (subscores of cohesion, expressiveness and conflict) and Family Relationship Index (FRI) (based on the subscores above). After adjusting for confounding factors (social phobia and maternal history of ADHD), the odds ratio (OR) for ADHD-I increased as the number of Rutter's indicators increased. Families of children with lower FES cohesion subscores presented higher OR for ADHD-I (OR 1.24; 95% confidence interval 1.05-1.45). Lower levels of FRI, a general index of family relationship, were also related to higher risk of ADHD-I (OR 1.11; 95% confidence interval 1.03-1.21). Our findings suggest that family adversity (in general), low family cohesion and low FRI (in particular) are associated with an increase in the risk for ADHD-I. However, the cross-sectional nature of the study limits our ability to infer causality.