Smoking during pregnancy and attention-deficit/hyperactivity disorder, predominantly inattentive type: A case-control study

OBJECTIVE: Few previous studies assessed specifically attention-deficit/ hyperactivity disorder, predominantly inattentive subtype (ADHD-I) in nonreferred samples. This study investigated the association between ADHD-I and prenatal exposure to nicotine. METHOD: In a case-control study performed between September 2002 and April 2005, we assessed a nonreferred Brazilian sample of 100 children and adolescents with ADHD-I and 100 non-ADHD controls (6-18 years old). Cases and controls, matched by gender and age, were screened using teacher reports in the Swanson, Nolan, and Pelham-IV (SNAP-IV) scale. They were systematically evaluated through structured diagnostic interviews. Prenatal exposure to nicotine and potential confounding factors were evaluated by direct interview with mothers. RESULTS: Adjusting for confounding factors (maternal ADHD, oppositional defiant disorder, birth weight, and alcohol use during pregnancy), children whose mothers smoked ≥10 cigarettes per day during pregnancy presented a significantly higher odds ratio for ADHD-I than children who were not exposed to nicotine during pregnancy (odds ratio 3.44; 95% confidence interval 1.17-10.06). Dimensional analyses showed significantly higher inattentive scores in subjects whose mothers smoked ≥10 cigarettes per day than in others after adjusting for confounding factors (p = .002). CONCLUSIONS: In a nonreferred sample, the authors expanded to ADHD-I previous findings documenting the association between prenatal exposure to nicotine and broadly defined ADHD in clinical samples. Copyright 2006