# Table 2 Descriptive statistics of samples and of mathematical performance

Participants descriptive statistics by group Mathematical test descriptive statistics
Publication Age range whole sample N (mean age, SD age) On medication during test Test name N (mean score, SD score) P value Quality rating
Antonini et al. [35] 7–11 49 (7.92, 1.11)C 45 (8.29, 1.34) No WIAT-II 97.06 (13.19)C 112.84 (18.7) <0.0001 C High
53 (8.36, 1.30)I 97.89 (13.79)I <0.0001 I
August et al. [49] 6–11 79 (8.90, 1.17) 61 (8.70, 1.19) NR WRAT-R 92.80 (16) 93.5 (17) >0.05 High
Barry et al. [32] 8–14 30 (11.10, 1.30)C 33 (11.24, 1.20) No MBA 1.52 (12.38)a 10.39 (12.77)a <0.05 High
3 (11.10, 1.30)I
Bauermeister et al. [31] 6–11 140 [(32.1%)C; (17.1%)I; (2.8%)U] (8.31, 1.70) NR (8.31, 1.70) No WPB-S β = −0.33I <0.001 High
Benedetto-Nasho et al. [25] 7–11 14 (9.55, 1.01) 15 (9.02, 1.14) No MCW 21.66 (12.13)P 47.32 (15.20)P <0.001 P High
52.53 (35.79)A 76.98 (18.04)A <0.05 A
11.31 (10.92)E 36.79 (15.24)E <0.001 E
Biederman et al. [44] Adults 84 (38.90, 9) 142 (NR) Yes WRAT-R 101.8 (15.30) 108.5 (14.70) <0.001 High
Biederman et al. [37] 6–17 128 (10.60, 3.00)b 109 (11.60, 3.70)b Yes WRAT-R 96.8 (17.40)b 111.30 (16.10)b < 0.05 b High
128 (14.40, 3.10)f 109 (15.2, 3.70)f 93.4 (18.30)f 109.50 (15.70)f < 0.05 f
Biederman et al. [46] 6–17 100 (9.0, NR)Y 69 (8.90, NR)Y NR WRAT-R 96.70 (16.50)Y,b 111.70 (15.90)Y,b <0.001 High
93.30 (18.30)Y,f 110.10 (16.20)Y,f
40 (14.40, NR)O 51 (15.20, NR)O 96.80 (19.00)O,b 111.10 (17.10)O,b
93.80 (18.20)O,f 108.40 (14.80)O,f
Biederman et al. [40] 6–18 140 (11.20, 3.40) 122 (12.20, Yes WRAT 95.50 (13.30) 106.20 (15.40) <0.001 High
DuPaul et al. [5] NR 95 (8.50, 1.20)C 53 (8.50, 1.10) Yes WJ-III 94.50 (12.70) 113.40 (10.30) <0.001 High
31 (8.50, 1.20)I
10 (8.50, 1.20)H
Efron et al. [41] 6 – 8 93 (7.3, 0.4)C 212 (7.3, 0.4) Yes WRAT 90.2 (14.7) 102.8 (13.4) <0.001 High
64 (7.3, 0.4)I Subtypes = NS individually
22 (7.3, 0.4)H β = –0.69
Faraone et al. [18] 6–17 93 (10.7, 3.10)b 120 (11.6, 3.70)b Yes WRAT-R 103.60 (14.40)b 111.30 (16.10)b <0.05 b Medium
83 (14.8, 3.20)f 109 (15.5, 3.70)f 98.80 (16.10)f 109.50 (15.70)f <0.05 f
Faraone et al. [45] 6–17 485 (10.90, NR)Y 78 (10.80, NR)Y NR WRAT-R 92.70 (22.50)Y 110 (15.20)Y <0.001 High
326 (10.90, NR)O 54 (10.80, NR)O 88 (25.00)O 111.8 (15.7)O
Frick et al. [26] 7–12 92 (9.50, NR)C 42 (10.60, NR) No BASIS Underachievers: 14 % C, 7 % I Underachievers:2% <0.05 C Medium
13 (9.50, NR)I >0.05I
Gremillion et al. [36] 6–12 266 (9.72, 1.50) 207 (9.79, 1.48) No WIAT-II 40.12 (9.39) 43.09 (9.22) <0.001
r = −0.27C <0.001 High
r = −0.22I <0.001
r = −0.28H <0.001
Greven et al. [50] NR 2191 (12, NR)MZ NR UNT, NNPT,CKT Genetic correlation:   High
3930 (12, NR)DZ ra = –0.41 (95 % CI: –0.47, –0.37)I Significant
rc = 0.12 (95 % CI: –0.12, 0.35)I NS
re = –0.20 (95 % CI: –0.23, –0.16)I Significant
ra = –0.22 (95 % CI: –0.28, –0.17)H Significant
rc = –0.27 (95 % CI: –0.44, –0.04)H Significant
re = 0.00 (95 % CI: –0.04, 0.04)H NS
Phenotypic correlation:
r = –0.26 (95 % CI: –0.28, –0.24)I Significant
r = –0.18 (95 % CI: –0.20, –0.16)H Significant
Hart et al. [19] NR 271 (9.82, 0.99)MZ NR WJ-III Genetic Covariance: <0.05 I High
159 (9.82, 0.99)DZ covar = 0.36 (95 % CI: 0.23, 0.50)I
covar = 0.31 (95 % CI: 0.27, 0.43)H
Shared environment: <0.05 H
covar = 0.90 (95 % CI: 0.84, 0.92)I
covar = 0.90 (95 % CI: 0.89, 0.92)H
Kaufmann & Nuerk [20] 8.8 –11.7 16 (10.20, 1.40) 16 (10.40, 1.30) NR NV-CNR 91.4 (10.16) 97.27 (2.55) 0.02 Medium
75 (24.15) 81.25 (17.08)
V-CNR 96.15 (4.58) 98.44 (2.54) 0.45
97.92 (3.02) 95.83 (11.39)
99.06 (2.02) 99.69 (1.25)
SMC 94.8 (5.61) 96.68 (3.12) 0.65
CMC 56.26 (20.20) 68.36 (18.45) 0.30
WMC 70.84 (25.97) 79.16 (17.87) 0.50
Kempton et al. [28] 6–12 15 (8.65, 1.53) 15 (8.81, 1.48) No WRAT 83.00 (10.92) 88.6 (15.72) >0.05 High
Laasonen et al. [33] 18–55 30 (31.60, 8.17) 40 (37.15, 11.70) No WAIS-III 10.90 (3.17) 12.18 (2.40) >0.05 Medium
Lamminmäki et al. [39] NR 17 (8.67, 1.28)C 22 (8.92, 1.4) Yes WJ-III Z-score: –0.53 (0.83) 0.070 High
–1.33 (0.06)C
20 (9.78, 1.33)I –0.88 (0.96)I
8 (8.60, 1.29)H –0.50 (1.14)H
Lewandowski et al. [21] 10–13 17 (11, NR)C 27 (11, NR) Yes WJ-III 92.59 (14.71) 102.11 (13.42) <0.05 High
7 (11, NR)I
3 (11, NR)H
Massetti et al. [38] 4–6b 85 (5.20, 0.70)C 130 (5.20, 0.08) Yes WJ-III β = −2.55, z = −1.92C (refers to longitudinal performance of children exhibiting ADHD-C symptoms across all waves of assessment) 0.060C High
14 (5.70, 0.50)I β = −6.49, z = −3.34I (refers to overall longitudinal performance) <0.001 I
12–14 f 26 (5.10, 0.80)H β = 0.40, z = 0.18H (refers to overall longitudinal performance) 0.360H
β = −7.27, z = −3.61C,f (overall performance using DSM-IV number of impairment settings to define subtypes) <0.001 C,f
Mayes & Calhoun [42] 6–16 724 (9, 2) 149 (9, 2) Yes WIAT, WIAT-II, WRAT-III 9 %d 4 %d <0.001 Medium
Mealer et al. [22] 6–13 20 (8.90, 2.08) 20 (8.50, 1.93) No WISC - III 8.70 (3.52) 10.60 (2.7) 0.063 Medium
Papaioannou et al. [48] 6–11   835 (103.90, 17.60) NR STAA Z-score: Z-score: 0.003 C High
24 (109.30, 17.10)C −0.80 (1.11)C 08 (0.97)
31 (103.90, 16.40)H −0.25 (0.99)H >0.5H
33 (100.10, 16.40)I −0.78 (1.07)I 0.0001 I
Penny et al. [29] 6–12 32 (8.65, 1.48)C 19 (8.40, 1.40) No WRAT-III 82.20 (17) 89.80 (15) >0.05 Medium
1I
Roy-Byrne et al. [34] 18–64 46 (33.10, 9.70) 46 (39.50, 11.20) No WRAT-R 90.20 (19.90) 100.60 (23.90) >0.05 High
Rucklidge et al. [23] 13–16 24 (14.68, 1.51)F 28 (15.31, 1.04)F No WRAT-III 96.33 (13.85)F 112.78 (12.34)F <0.001 High
35 (14.80, 1.22) M 20 (14.8, 1.22)M 90.57 (15.697)M 108.20 (10.11)M NR
Schachar & Tannock [30] 7–11 22 (9.20, 1.20) 16 (9.0, 1.4) NR WRAT-R 92.40 (9.00) 97.60 (13.80) >0.05 Medium
Seidman et al. [24] 6–17 43 (NR, NR) 36 (NR, NR) Yes WRAT-R 95.70 (16.00) 107.60 (14.30) <0.05 Medium
Thorell [27] 6–7 21 (6.30, 0.49) 124 (6.30, 0.49) NR NS r = –0.28I <0.001 I Medium
r = –0.13H >0.05H
Todd et al. [43] 7–17 149 (13.70, 3.00)C 731 (14.20, 3.10) Yes WRAT-III 87.3 (13.60)C   <0.001 C High
243 (14.30, 3.00)I 89.40 (13.50)I 96.60 (13.40) <0.001 I
31 (15.30, 3.10)H 95.50 (11.20)H   >0.05H
Zentall et al. [47] 7–15 107 (NR, NR) 121 (NR, NR) NR CAT 55.64 (2.97) 75.11 (3.00) <0.001 High
TAT F(2,223) = 58.5 (addition) 61.23 (NR) <0.001
F(2,223) = 27.95 (subtraction) 32.60 (NR)
F(2,205) = 75.23 (multiplication) 91.79 (NR)
1. Descriptives of samples and of mathematical performance. Numbers in bold highlight significant results
2. N, Sample size; SD, Standard deviation; NR, Not reported; 95 % CI, 95 % confidence interval; Z-score, Represents achievement scores normalized and residualized for intelligence scores; ra, Genetic correlation; rc, Shared environmental correlation; re, Non-shared environmental correlation; covar, Covariance; C, Predominantly combined-type; I, Predominantly inattentive-type; H, Predominantly hyperactive-type; U, Unspecified; MZ, Monozygotic twin pairs; DZ, Dizygotic twin pairs; Y, Young; O, Old (adolescents); b, Baseline; f, Follow-up; F, Female; M, Male; a, The values demonstrate discrepancy between predicted achievement on the Kaufman Brief Intelligence Test Composite [58] and actual math achievement on the Mini Battery of Achievement (MBA) test [59] with a positive score representing actual achievement above the predicted score as estimated by participant’s intellectual level, and a negative score representing actual achievement below the predicted score; P, Productivity (number of math problems attempted out of the total); A, Accuracy (percentage of problems answered correctly out of those attempted); E, Efficiency (number of correctly completed items out of total number of items available); d, Discrepancy between Intelligence quotient (IQ) and mathematics score
3. NB: on average, ADHD children scored lower on the test than their intended IQ (<IQ of 104.8) and controls scored higher on the test than their intended IQ (>IQ of 97.5)
4. Tests: WIAT-II, Wechsler Individual Achievement Test – Second Edition; WRAT-R, Wide Range Achievement Test-Revised; MBA, Woodcock-McGrew-Werder Mini-Battery of Achievement; WPB-S, Woodcock Psychoeducational Battery–Spanish; MCW, Math computational worksheet; WRAT, Wide Range Achievement Test; WJ-III, Woodcock-Johnson III achievement test; BASIS, Basic Achievement Skills Individual Screener; UNT, Understanding Number test; NNPT, Non-numerical Processes test; CKT, Computation and Knowledge test; BA, Basic arithmetic; NV-CNR, Core numerical representations – non-verbal magnitude representations; V-CNR, Core numerical representations – verbal representations; SMC, Simple mental calculation; CMC, Complex mental calculation; WMC, Written mental calculation; WAIS-III, Wechsler Adult Intelligence Scale – Third edition; WJ-R, Woodcock-Johnson achievement test-Revised; WIAT-NO, Wechsler Individual Achievement Test Numerical Operations; WIAT, Wechsler Individual Achievement Test; WRAT-III, Wide Range Achievement Test-Third Edition; WISC-III, Wechsler Intelligence Scale for Children – Third Edition; STAA , Screening test of arithmetic ability; PMS, Pupil Monitoring System; NS, Not specified; CAT, California Achievement Test; TAT, Timed Arithmetic Trial