Dopamine transporter 3'UTR VNTR genotype is a marker of performance on executive function tasks in children with ADHD

Table 1 Demographic and clinical characteristics of sample partitioned by DAT1 genotype

	9/10 genotype	10/10 genotype	Statistics and p values
	n = 96	n = 127	Total n = 223
Age (yrs)	8.8 ± 1.8	9.2 ± 1.9	F = 2.78, p = .10
Proportion of males	80.2% (n = 77)	79% (n = 100)	χ² = 0.072, p = .79
Proportion of Caucasians	87.5% (n = 84)	82.7% (n = 105)	χ² = 0.98, p = .32
WISC-III FSIQ	96.7 ± 14.6	99.2 ± 14.4	F = 1.61, p = .21
CBCL total	70 ± 8.1	69.2 ± 9.3	F = 0.41, p = .35
CBCL Attention problems	70.7 ± 9.5	70.8 ± 10.2	F = 0.009, p = .92
CBCL externalisation	70.4 ± 9.4	69.1 ± 10.2	F = 0.65, p = .42
CBCL internalisation	63.7 ± 9.6	64.1 ± 11.4	F = 0.063, p = .80
Proportion with I/H/C ADHD subtype as assessed by the treating psychiatrist	18% (n = 17)/6% (n = 6)/74% (n = 71) 2 missing data points	27% (n = 34)/4% (n = 5)/65% (n = 82) 6 missing data points	χ² = 3.21, p = .20
DISC-IV Inattentive	6.9 ± 2.2	7.2 ± 2.0	F = 0.51, p = .48
DISC-IV Hyperactive/Impulsive	6.3 ± 2.4	5.6 ± 2.5	F = 3.56, p = .061
with CD/without CD	32% (n = 30)/68% (n = 64) 2 missing data points	24% (n = 30)/76% (n = 94) 3 missing data points	χ² = 1.6, p = .21
with ODD/without ODD	40% (n = 38)/60% (n = 56) 2 missing data points	41% (n = 52)/59% (n = 74) 1 missing data point	χ² = 0.016, p = .90
Never/previously medicated	52% (n = 46)/48% (n = 43) 7 missing data points	52% (n = 60)/48% (n = 56) 11 missing data points	χ² < 0.001, p = .99

Values are percentages or means ± their respective Standard Deviations (SD). Demographic and clinical characteristics were compared between the two groups using the appropriate statistic. WISC = Wechsler Intelligence Scale for Children, 3rd edition; CBCL = Child Behavioural Checklist; I/H/C = Inattentive/Hyperactive/Combined; DISC = Diagnostic Interview Schedule for Children, 4^th edition; ODD = Oppositional Defiant Disorder; CD = Conduct Disorder; Percentages are rounded to the nearest unit. Note that in the DSM-IV, a diagnosis of CD supersedes a diagnosis of ODD. However, in order to make the table as informative as possible, this criterion was relaxed. Age was used as a covariate for all F statistics.

ISSN: 1471-244X