title: Laterality, hand control and scholastic performance: a British birth cohort study.
abstract: OBJECTIVE
  To use simple measures of laterality and hand control that can identify a greater risk of poorer scholastic ability, potentially signalling suboptimal hemispheric lateralisation.
  
  
  METHODS
  Analysis of material from a birth cohort study.
  
  
  METHODS
  Members of the National Child Development Study, a British birth cohort study following people born in 1958.
  
  
  METHODS
  10 612 children who undertook tests at age 11 years.
  
  
  METHODS
  Teacher-administered tests of non-verbal general ability, verbal general ability, reading comprehension and mathematics.
  
  
  RESULTS
  Linear regression produced associations (and 95% CIs) with tests of verbal general ability, non-verbal general ability, reading comprehension and mathematics scores for the lowest third (compared with highest) of a left-hand control test involving picking up matches of -1.21 (-1.73 to -0.68; p<0.001), -0.72 (-1.14 to -0.29; p=0.001), -0.70 (-1.06 to -0.35; p<0.001) and -1.32 (-1.90 to -0.73; p<0.001). Among those in the lowest third of the right-hand control test score, mixed-handedness compared with right-handedness was associated with poorer scholastic performance, with regression coefficients (and 95% CIs; p values) of 1.90 (-3.01 to -0.80; p=0.001), -1.25 (-2.15 to -0.35; p=0.007), -1.28 (2.04 to -0.53; p=0.001) and -1.33 (-2.53 to -0.13; p=0.030). The estimates are for a point change in the scholastic test scores, after adjustment for sex, left-hand motor function and social class. Statistically significant associations with mixed-handedness were only observed for the lowest third of right-hand motor function.
  
  
  CONCLUSIONS
  Measures involving poorer left-hand motor function may represent useful markers of reduced cognitive function possibly reflecting suboptimal hemispheric lateralisation. Crude measures of laterality such as reported non-right-handedness may be more useful for research when combined with measures of motor function.
authors.affiliation: Psychiatric Research Centre, Örebro County Council, Örebro, Sweden.
authors.forename: Tabita
authors.initials: T
authors.lastname: Björk
authors.forename: Ole
authors.initials: O
authors.lastname: Brus
authors.forename: Walter
authors.initials: W
authors.lastname: Osika
authors.forename: Scott
authors.initials: S
authors.lastname: Montgomery