Inteligência e aleitamento materno em adolescentes da coorte de nascimentos de São Luís, Maranhão, Brasil, 1997/1998

Abstract

Objective: to describe performance in intelligence tests and verify the association with demographic and socioeconomic variables of adolescents and adults in three Brazilian cities Ribeirão Preto, Pelotas and São Luís; and analyze the association between breastfeeding and Intelligence Quotient (IQ) of adolescents belonging to the São Luís 1997/1998 cohort. Methods: the first article is a cross-sectional study carried out with data from 12,710 adolescents and adults participating in five Birth Cohorts: Ribeirão Preto cohorts of 1978/1979 and 1994, Pelotas cohorts of 1982 and 1993 and São Luís cohort of 1997/1998. IQ was calculated from the total score of the Wechsler Adult Intelligence Scale (WAIS-III). The outcome was compared between and within cohorts according to sex, education and income. The second article is a longitudinal study with data obtained in the third phase of the São Luís 1997/1998 cohort, carried out with adolescents aged 18 and 19. The exposure variable was breastfeeding and the outcome variable was IQ. A theoretical model was constructed using the directed acyclic graph (DAG) to identify the variables of the minimum adjustment set for confounding. Multiple linear regressions were performed to obtain adjusted coefficients in the R 4.3.1 software. A significance level of 5% was adopted. Results: Article 1 showed that male adolescents and adults, with more years of schooling (≥12 years), higher income (3rd tertile) and belonging to families with a more educated head (≥12 years) obtained the highest averages of IQ (p<0.001). Differences of 15.2 and 21.6 points in IQ according to income and education were observed, while differences in IQ between cities and sexes were of small magnitude. Regarding the results of article 2, the average IQ of the 301 adolescents was 99.7 points ± 11.2. The average breastfeeding time in months was 3.26 months ± 3.34. In the crude analysis, no statistically significant association was identified between breastfeeding time and adolescents' IQ. The result was maintained even after adjusting for confounding factors for those breastfed for up to one month (1.55; CI% -3.25;6.63), two to three months (0.55; CI95% -4.99;6 .11), four to six months (2.89; 95%CI -2.36;8.14) and more than six months (-1.97; 95%CI -8.37;4.42), ever breastfed (1.42; 95%CI -3.33;6.19) and exclusive breastfeeding (0.70; 95%CI -2.46;3.88). Conclusion: The cohorts presented approximate average IQ values. Greater differences in intra-cohort IQ averages according to income and education may indicate lower human capital for more disadvantaged groups. Breastfeeding is not associated with the IQ of adolescents in the study sample.