The enrichment study of the Minnesota twin family study: increasing the yield of twin families at high risk for externalizing psychopathology.
The Enrichment Study (ES) was designed to extend the Minnesota Twin Family Study (MTFS) by oversampling 11-year-old twins at especially high risk for substance use disorders by virtue of having a childhood disruptive disorder. The sample was ascertained from Minnesota birth records. To identify high-risk twins, we conducted telephone screening interviews for parent-reported symptoms of attention-deficit/hyperactivity disorder (ADHD) and conduct disorder (CD) as well as indications of academic disengagement. Twins who exceeded a predetermined threshold were invited to participate. To facilitate comparison with the previously ascertained MTFS participants, a random sample of 11-year-old twins was also recruited. As part of the ES study, 499 twin pairs, and their parents, visited the University of Minnesota, where each participant completed a clinical interview, psychophysiological evaluation, and thorough assessment of environmental risk. We were highly successful in recruiting at-risk twins; 52% of the screened male twins and 41% of the screened females met criteria for a diagnosis of ADHD, CD, or oppositional defiant disorder (ODD). At the pair level, 63% of the screened pairs had at least one member with a childhood disruptive disorder. This article provides an overview of the study design and includes a review of recent findings using this sample of twins.
Department of Psychology, University of Minnesota, Minneapolis, MN 55455United States of America. mkeyes@tfs.psych.umn.edu
Margaret A
MA
Keyes
Stephen M
SM
Malone
Irene J
IJ
Elkins
Lisa N
LN
Legrand
Matt
M
McGue
William G
WG
Iacono
D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis / Q000523:psychology; D019958:Attention Deficit and Disruptive Behavior Disorders / Q000175:diagnosis* / Q000523:psychology*; D002648:Child; D019955:Conduct Disorder / Q000175:diagnosis / Q000523:psychology; D004200:Diseases in Twins / Q000175:diagnosis* / Q000523:psychology*; D005260:Female; D006801:Humans; D007389:Internal-External Control; D008297:Male; D008910:Minnesota; D011569:Psychiatric Status Rating Scales; D018433:Twin Studies as Topic