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BackgroundA variety of methodologies and techniques converge on the notion that adults and children with attention deficit hyperactivity disorder (ADHD) have similar deficits, but there is limited knowledge about whether adult retrospective reports reflect similar genetic and environmental influences implicated in childhood ADHD.MethodDSM-IV ADHD symptoms were collected retrospectively from 3896 young adults participating in the National Longitudinal Study of Adolescent Health. Responses from this genetically informative sample of same- and opposite-sex twins and siblings were used to determine the magnitude of genetic and environmental influences. Possible gender differences in these effects were also examined. The degree of familial specificity of the genetic and environmental influences on the Inattentive and Hyperactive-Impulsive symptom dimensions was also determined.ResultsAdditive genetic effects contributed moderately to DSM-IV Inattentive, Hyperactive-Impulsive and Combined ADHD subtypes (heritability estimates of 0.30?0.38). Individual-specific influences accounted for the remaining proportion of the variance. Both genetic and individual-specific environmental effects contributed to the covariation of Inattentive and Hyperactive-Impulsive symptomologies.ConclusionsResults from our genetic analyses agree with previous findings based on self-assessment of current and retrospectively reported ADHD symptoms in adolescents and adults. Large individual-specific environmental influences as identified here suggest that current questionnaires used for retrospective diagnoses may not provide the most accurate reconstruction of the etiological influences on childhood ADHD in general population samples. [ABSTRACT FROM AUTHOR]

Background: Previous studies on assortment for psychiatric disorders have reported discrepant findings. We aimed to test whether there is a significant association for psychiatric diagnoses, including alcoholism, generalized anxiety disorder, major depressive disorder, panic disorder and phobias between husbands and wives in two population-based samples. We further evaluated whether marital resemblance occurs primarily within or across psychiatric disorders and if assortment for psychopathology is primary or secondary to assortment for correlated variables., Methods: A model for mate selection addressed whether the correlation between mates for psychiatric disorders arises from direct assortment (primary homogamy) or through correlation with other variables for which assortment occurs (secondary homogamy) or through cross-variable assortment. The model accounted for within-person co-morbidity as well as across-spouse data., Results: Findings suggested that a moderate degree of assortment exists both within and across psychiatric diagnoses. Only a small amount of the observed marital resemblance for mental illness could be explained by assortment for correlated variables such as age, religious attendance and education. Similar results were obtained for the two samples separately and confirmed in their joint analysis, revealing that the co-morbidity and assortment findings, except for the marital correlation for age, religious attendance and education, replicate across samples., Conclusions: Significant but moderate primary assortment exists for psychiatric disorders. The bias in twin studies that have ignored the small amount of assortment is negligible.