Table 1 Study population characteristics and cognitive performance outcomes of the participating schoolchildren (n = 307)
Population characteristics | |
 Boys | 154 (50.2%) |
 Age | 10.4 ± 1.2 |
 Body mass index, kg/m2 | 17.2 ± 2.8 |
 Study area | |
  Kiewit (Hasselt) | 68 (22.1%) |
  Tienen | 62 (20.2%) |
  Zonhoven | 177 (57.7%) |
 Education level of the mother | |
  Secondary education or lower | 118 (38.4%) |
  College or university degree | 189 (61.6%) |
 Highest parental occupational category of either parent | |
  Unemployed or not qualified worker | 26 (8.5%) |
  Qualified worker, white-collar assistant, or teaching staff | 123 (40.0%) |
  Self-employed, specialist, or member of the management | 158 (51.5%) |
 Passive smoking | 41 (13.4%) |
Cognitive performance outcomes | |
 Sustained and selective attention | |
  Continuous performance test, msec (n = 307) | 593.3 ± 46.2 |
 Selective attention | |
  Stroop test, msec (n = 305) | 1424.0 ± 305.1 |
 Short-term memory | |
  Digit span forward test, digits (n = 305) | 5.2 ± 0.8 |
  Digit span backward test, digits (n = 306) | 4.0 ± 0.8 |
 Visual information processing speed | |
  Pattern comparison test, sec (n = 299) | 4.2 ± 0.9 |
  Digit symbol test, sec (n = 307) | 123.6 ± 21.5 |