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. Author manuscript; available in PMC: 2010 Nov 24.
Published in final edited form as: Neuroscience. 2009 Feb 3;164(1):16–29. doi: 10.1016/j.neuroscience.2009.01.056

TABLE 1. Twin sample demographics.

AP status: attention/hyperactivity status of twin pair; Twin pairs: number of female (F) and male (M) twin pairs; Age: age at time of MRI exam (in years); Mean AP T-score: mean CBCL-AP T-scores; Anxiety problems T-score: mean DSM-Oriented Anxiety problems T-scores; Oppositional Defiant problems T-score: mean DSM-Oriented Oppositional Defiant problems T-scores; Conduct problems T-score: mean DSM-Oriented Conduct problems T-scores. DSM-Oriented scales are based on CBCL4/18 items very consistent with the relevant DSM-IV category (Achenbach et al., 2003). All mean scores are across 2 or 3 time points (7, 10 and 12 years), and computed separately for boys and girls. Birth weight: birth weight of each twin in grams. Data separated by a forward slash refer to first and second born twins for concordant high and low risk twin pairs, and to the high versus low risk co-twin for the discordant pairs.

AP status Twin pairs Age Mean CBCL-AP T-score Anxiety problems T-score Oppositional Defiant problems T-score Conduct problems T-score Birth weight
Concordant high 6F / 2M mean 15.35 74.16 / 79.93 57.09 / 61.87 63.41 / 61.63 54.57 / 52.62 2547 / 2374
st. dev 1.57 7.62 / 6.93 8.72 / 11.02 10.30 / 10.12 5.02 / 3.56 523 / 428
Concordant low 4F / 6M mean 15.40 42.93 / 41.63 46.62 / 44.02 41.95 / 43.63 45.22 / 45.19 2642 / 2603
st. dev 1.29 3.50 / 2.86 5.08 / 2.53 2.66 / 4.30 2.15 / 1.94 553 / 384
Discordant 7F / 2M mean 14.76 72.53 / 46.64 60.70 / 48.98 56.54 / 51.60 55.51 / 54.34 1968 / 2489
st. dev 1.48 7.77 / 4.45 11.41 / 7.48 10.39 / 12.21 8.26 / 14.01 604 / 466