The ALSPAC Coordination Test (subtests of the Movement ABC): Methodology and data on associations with prenatal exposures to lead, cadmium and mercury

Abstract

As part of the Avon Longitudinal Study of Parents and Children (ALSPAC), measures of child motor skills were collected in research clinics. The ALSPAC Coordination Test was derived from subtests of the Movement ABC at age 7 years in children participating in ALSPAC. Maternal blood lead, cadmium and mercury concentrations were measured by inductively-coupled plasma mass spectrometry in samples from women at a median gestation age of 11 weeks. Maternal reports at 32 weeks’ gestation were used to generate data on a range of potential confounders. The data were used to determine the associations between prenatal exposure to lead, cadmium and mercury and child motor skills at age 7 years. For results, please see Taylor et al. [1].

Prenatal lead, cadmium and mercury exposure and associations with motor skills at age 7 years in a UK observational birth cohort

“…There were no other associations shown in the adjusted models. Analyses with exposures as continuous variables showed similar results, except that the association of cadmium with balance was retained after adjustment, but there were no associations of any outcome with mercury exposure in either unadjusted or adjusted models (Table 2 in Taylor et al (2018) ). Models comparing the lowest quartile of lead, cadmium or mercury exposure with the top quartile also showed that there were no associations between the prenatal exposures and the Movement ABC subtest results in adjusted models ( Table 4 ).…”

“…Models comparing the lowest quartile of lead, cadmium or mercury exposure with the top quartile also showed that there were no associations between the prenatal exposures and the Movement ABC subtest results in adjusted models ( Table 4 ). Additional adjustment for the gestational age at which the prenatal blood samples were taken made very little difference to the results (Table 3 in Taylor et al (2018) ).…”

“…In each case the tester also rated the child's attempt at the task as good, medium or poor. Details of the methodology for each subtest (balance: heel to toes steps subtest; ball skills: beanbag subtest; manual dexterity: placing pegs subtest; manual dexterity: threading lace subtest) are described in detail in Taylor et al (2018) . Subtest results were categorised as follows: heel to toe subtest 15 steps completed (pass) versus <15 steps completed (fail) ( Humphriss et al, 2011 ); beanbag subtest 4–10 throws accurate (pass) or 0–3 throws accurate (fail) (poor skills defined as <1 SD from mean ( Golding et al, 2014b )); threading lace 9–21 s (pass) versus 22–105 s (fail) (based on median value); peg board preferred hand 15–22 s (pass) versus 23–46 s (fail) (based on median value); peg board non-preferred hand 15–25 s (pass) versus 35–62 s (fail) (based on median value).…”

“…Children with probable DCD met all four DSM-IV criteria. Details of the inclusion and exclusion criteria are described in detail in Taylor et al (2018) .…”

“…Multiple imputation was not undertaken: few data were missing from the set of confounders and so imputation was unlikely to affect the results substantially (for example, for cases with a valid prenatal lead measurement and a complete set of outcomes the percentages of missing data on confounders were: sex 0%, maternal education attainment 3.6%, smoking 5.5%, alcohol 10.1%, age 0.6%, parity 5.4%). Data from complete cases are presented in the main paper and data from all available cases are shown in Taylor et al (2018) .…”