Relationship between adiposity and cognitive performance in 9-10-year-old children in South India

Background Studies in high-income countries have shown inverse associations between adiposity and cognitive performance in children. We aimed to examine the relationship between adiposity and cognitive function in Indian children. Methods At a mean age of 9.7 years, height, weight, triceps and subscapular skinfold thicknesses and waist circumference were recorded for 540 children born in Mysore, India. Body fat percentage was estimated using bioimpedance. Cognitive function was assessed using three core tests from the Kaufman Assessment Battery for children-II edition and additional tests measuring learning, short-term memory, reasoning, verbal and visuo-spatial abilities, attention and concentration. Data on the parents' socioeconomic status, education, occupation and income were collected. Results According to WHO definitions, 3.5% of the children were overweight/obese (Body Mass Index (BMI) >+1SD) and 27% underweight (BMI<-25D). Compared to normal children, overweight/obese children scored higher in tests of learning/long-term retrieval, reasoning and verbal ability (unadjusted p<0.05 for all). All the Cognitive Test scores increased with increase in BMI and skinfold thickness, (unadjusted beta=0.10-0.20 SD; p<0.05 for all). The effects, though attenuated, remained mainly significant after adjustment for age, sex and socioeconomic factors. Similar associations were found for waist circumference and percentage body fat. Conclusions In this Indian population, in which obesity was uncommon, greater adiposity predicted higher cognitive ability. These associations were only partly explained by socioeconomic factors. Our findings suggest that better nutrition is associated with better cognitive function, and that inverse associations between adiposity and cognitive function in high-income countries reflect confounding by socioeconomic factors.