Contributions of parental alcoholism, prenatal substance exposure, and genetic transmission to child ADHD risk: a female twin study.
BACKGROUND
Genetic influences have been shown to play a major role in determining the risk of attention-deficit hyperactivity disorder (ADHD). In addition, prenatal exposure to nicotine and/or alcohol has also been suggested to increase risk of the disorder. Little attention, however, has been directed to investigating the roles of genetic transmission and prenatal exposure simultaneously.


METHODS
Diagnostic telephone interview data from parents of Missouri adolescent female twin pairs born during 1975-1985 were analyzed. Logistic regression models were fitted to interview data from a total of 1936 twin pairs (1091 MZ and 845 DZ pairs) to determine the relative contributions of parental smoking and drinking behavior (both during and outside of pregnancy) as risk factors for DSM-IV ADHD. Structural equation models were fitted to determine the extent of residual genetic and environmental influences on ADHD risk while controlling for effects of prenatal and parental predictors on risk.


RESULTS
ADHD was more likely to be diagnosed in girls whose mothers or fathers were alcohol dependent, whose mothers reported heavy alcohol use during pregnancy, and in those with low birth weight. Controlling for other risk factors, risk was not significantly increased in those whose mothers smoked during pregnancy. After allowing for effects of prenatal and childhood predictors, 86% of the residual variance in ADHD risk was attributable to genetic effects and 14% to non-shared environmental influences.


CONCLUSIONS
Prenatal and parental risk factors may not be important mediators of influences on risk with much of the association between these variables and ADHD appearing to be indirect.
Knopik
Valerie S
VS
Center for Alcohol and Addiction Studies, Department of Community Health, Brown University Medical School, Providence, RI 02912, USA. valerie_knopik@Brown.edu
Sparrow
Elizabeth P
EP
Madden
Pamela A F
PA
Bucholz
Kathleen K
KK
Hudziak
James J
JJ
Reich
Wendy
W
Slutske
Wendy S
WS
Grant
Julia D
JD
McLaughlin
Tara L
TL
Todorov
Alexandre
A
Todd
Richard D
RD
Heath
Andrew C
AC
D000293:Adolescent; D000437:Alcoholism / Q000235:genetics* / Q000523:psychology*; D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis / Q000453:epidemiology*; D016241:Child of Impaired Parents / Q000706:statistics & numerical data*; D039721:Diagnostic and Statistical Manual of Mental Disorders; D000431:Ethanol / Q000008:administration & dosage / Q000009:adverse effects*; D005260:Female; D006801:Humans; D010290:Parents / Q000523:psychology*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D012307:Risk Factors; D014427:Twins / Q000235:genetics*
D000431:Ethanol