OBJECTIVE: There is a persistent theory that birth stress and subsequent brain pathology play an important role in the manifestation of left-handedness. Evidence for this theory, however, is mixed and studies are often beset with problems related to small sample sizes and unreliable health reports. METHOD: TO avoid these issues, this study used a sample of approximately 10,000 children from the British Cohort Study. The study contains objective birth-health reports and comprehensive measures of socioeconomic status, handedness, cognitive ability, and behavioral/health issues. RESULTS: Regression analyses showed that variables associated with birth stress affected cognitive/behavioral/health outcomes of the child. Despite this, these same factors did not affect the direction or degree of hand preference. CONCLUSIONS: We have therefore demonstrated a dissociation whereby adverse birth factors affect the brain's cognitive ability, but not handedness, and by implication, cerebral lateralization. The study also demonstrated a link between left-handedness and reduced levels of cognitive ability. This link cannot be due a generalized birth-stress mechanism and may be caused by specific mechanisms related to changes in cerebral dominance.
OBJECTIVE: There is a persistent theory that birth stress and subsequent brain pathology play an important role in the manifestation of left-handedness. Evidence for this theory, however, is mixed and studies are often beset with problems related to small sample sizes and unreliable health reports. METHOD: TO avoid these issues, this study used a sample of approximately 10,000 children from the British Cohort Study. The study contains objective birth-health reports and comprehensive measures of socioeconomic status, handedness, cognitive ability, and behavioral/health issues. RESULTS: Regression analyses showed that variables associated with birth stress affected cognitive/behavioral/health outcomes of the child. Despite this, these same factors did not affect the direction or degree of hand preference. CONCLUSIONS: We have therefore demonstrated a dissociation whereby adverse birth factors affect the brain's cognitive ability, but not handedness, and by implication, cerebral lateralization. The study also demonstrated a link between left-handedness and reduced levels of cognitive ability. This link cannot be due a generalized birth-stress mechanism and may be caused by specific mechanisms related to changes in cerebral dominance.
Authors: Leona Pascoe; Shannon E Scratch; Alice C Burnett; Deanne K Thompson; Katherine J Lee; Lex W Doyle; Jeanie L Y Cheong; Terrie E Inder; Peter J Anderson Journal: J Int Neuropsychol Soc Date: 2015-09-02 Impact factor: 2.892
Authors: Kauko Heikkilä; Catharina E M Van Beijsterveldt; Jari Haukka; Matti Iivanainen; Aulikki Saari-Kemppainen; Karri Silventoinen; Dorret I Boomsma; Yoshie Yokoyama; Eero Vuoksimaa Journal: Proc Natl Acad Sci U S A Date: 2018-05-14 Impact factor: 11.205