Intellectual ability and nutritional status assessed through anthropometric measurements of Chilean school-age children from different socioeconomic status

This study was designed to investigate the interrelationships between intel lectual ability (IA), nutritional status measured through anthropometric me asurements and socio-economic and socio-cultural parameters. A representati ve sample of 4,509 school-age children according to grade, sex, type of sch ool and geographic area was chosen from Chile's Metropolitan Region. School -age children 5 to 22 years of age belonged to elementary and high schools. The cross-sectional research was carried out in 1986-1987. IA was measured by means of the Raven's Progressive Matrices Test. The Z-scores for weight (Z-W) and height (Z-H) and the percentage of adequacy weight/height (% W/H ), were compared with WHO tables; the Z-scores for head circumference (Z-HC ) with Tanner tables and brachial anthropometric measurements with Frisanch o standards. Socio-economic status (SES) was determined using Graffar's mod ified method. Statistical procedures included analysis of variance, Scheffe 's test for comparison of means, correlation and regression. IA positively and significantly correlated with Z-HC, Z-H, Z-W and brachial anthropometri c parameters; however, Z-HC is the anthropometric index with the greatest e xplanatory power in IA variance, followed by Z-H. Z-HC increased its explan atory power in IA variance with age and in school-age children 16 years of age or more this was the only anthropometric parameter that explained IA va riance (F = 22.56, p < 0.0001; r(2) = 0.142). Independent of SES and age, i n the total sample, Z-HC, sex, maternal and household head schooling, Z-H, sewerage and quality of housing, were the independent variables with the gr eatest explanatory power in IA variance (F = 43.03, p < 0.0001, r(2) = 0.17 6), in males, (F = 22.04, p < 0.0001, r(2) = 0.159) and in females (F = 25. 98, p < 0.0001, r(2) = 0.191), the only group in which Z-H entered in the s tatistical model. Taking into consideration that HC is an indicator of nutr itional background and brain development, these results may provide the bas is for further research related with the impact of malnutrition at an earli er age on IA, HC and subsequent brain development and for improved nutritio nal and educational planning.