Sex of older siblings and cognitive function

• Background : Number of older siblings is associated with lower cognitive function, possibly as marker of material disadvantage. Sex differences may signal an influence of inter-sibling interactions.Methods: The study used a national Swedish register-based cohort of men (n=644,603), born between 1970 and 1992 who undertook military conscription assessments in adolescence that included cognitive function measured on a normally-distributed scale of 1-9. Associations with siblings were investigated using linear regression.Results: After adjustment for numbers of younger siblings, year of conscription assessment, age/year of birth, sex, European socioeconomic classification for parents and maternal age at delivery; the regression coefficients (and 95% confidence intervals) for cognitive function are -0.26 (-0.27, -0.25), -0.42 (-0.44, -0.40), and -0.72 (-0.76, -0.67) for one, two and three or more male older siblings, respectively, compared with none; and -0.22 (-0.23, -0.21), -0.39 (-.41, -0.37), -0.62 (-0.67, -0.58) for one two and three or more female older siblings, respectively, compared with none. A larger number of younger siblings is not associated with lower cognitive function in the adjusted model.Conclusions: Family size is associated with cognitive function: older male siblings may have greater implications than females due to their demands on familial resources or through inter-sibling interactions.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine (hsv//eng)

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