Are perinatal complications relevant to the manifestation of ADD? Issues of comorbidity and familiality.

We evaluated the role of pregnancy, delivery, and infancy complications (PDICs) in the etiology of attention deficit disorder (ADD) addressing issues of comorbidity and familiarity by formulating and testing multiple hypotheses. Subjects were six to 17-year-old boys with DSM-III attention deficit disorder (ADD, N = 73), psychiatric (N = 26), and normal (N = 26) controls and their relatives. Information on PDICs was obtained from the mothers in a standardized manner blind to the proband's clinical status. Using odds ratio analyses, an association was found between ADD and PDICs that was strongest for the comorbid and nonfamilial subtypes. In contrast, noncomorbid and familial ADD subgroups differed less from normal controls in the risk for PDICs. The increased risk for PDICs in nonfamilial ADD children and the lack of evidence for increased risk among familial ADD patients suggests that PDICs may be part of nongenetic etiologic mechanisms in this disorder, especially for children who have comorbid disorders.