Table 1 Characteristics of the study population

Age and anthropometry

N

M (SD)

M (SD)

M (SD)

F

p-value

η²

 Age (years)

1277

8.3 (1.4)

8.4 (1.5)

8.2 (1.4)

6.2

0.013

0.005

 Height (cm)

1240

124.7 (9.2)

125.1 (9.0)

124.3 (9.4)

2.9

0.087

0.002

 Weight (kg)

1240

25.4 (6.9)

25.4 (6.6)

25.4 (7.2)

0.0

0.884

0.000

 BMI (kg/m²)

1240

16.1 (2.6)

16.0 (2.4)

16.1 (2.8)

0.5

0.470

0.000

Sociocultural characteristics

N

M (SD)

M (SD)

M (SD)

F

p-value

η²

 Socioeconomic status (SES)

740

3.0 (1.2)

3.0 (1.2)

3.0 (1.2)

0.4

0.539

0.001

 Food insecurity*

940

1.3 (0.6)

1.3 (0.6)

1.2 (0.6)

2.6

0.111

0.003

Helminth infections and stunting

N

n (%)

n (%)

n (%)

χ²

p-value

 Infected

1245

89 (7.1)

50 (7.8)

39 (6.5)

0.8

0.383

 Stunted

1231

112 (9.1)

48 (7.6)

64 (10.7)

3.6

0.057

Physical fitness

N

M (SD)

M (SD)

M (SD)

F

p-value

η²

 Grip strength (in kg)

1277

10.3 (12.0)

11.8 (12.9)

9.7 (10.9)

2.5

0.114

0.002

 Cardiorespiratory fitness (VO₂max; in ml kg⁻¹ min⁻¹)

1277

43.9 (22.9)

44.1 (22.9)

43.7 (22.9)

0.1

0.761

0.000

Academic achievement

N

M (SD)

M (SD)

M (SD)

F

p-value

η²

 End of year results

1045

4.6 (1.3)

4.4 (1.2)

4.8 (1.3)

35.9

0.000

0.033

 Language

1045

4.5 (1.3)

4.3 (1.2)

4.8 (1.3)

36.3

0.000

0.034

 Mathematics

1045

4.7 (1.3)

4.4 (1.2)

4.9 (1.4)

30.4

0.000

0.028

 Life skills

1045

5.0 (1.0)

4.8 (1.0)

5.2 (1.0)

39.7

0.000

0.037

Flanker task

N

M (SD)

M (SD)

M (SD)

F

p-value

η²

 Accuracy (congruent stimuli)

1223

92.8 (10.8)

92.6 (11.1)

92.9 (10.5)

0.2

0.651

0.000

 Accuracy (incongruent stimuli)

1223

84.9 (19.4)

85.4 (18.2)

84.4 (20.6)

0.7

0.397

0.001

 Reaction time (congruent stimuli)

1223

1187.9 (240.4)

1155.7 (243.5)

1222.2 (232.3)

23.9

0.000

0.019

 Reaction time (incongruent stimuli)

1223

1273.6 (266.6)

1238.6 (262.5)

1310.9 (266.0)

22.7

0.000

0.018