Non-verbal intelligence indicates the ability to learn, analyze, comprehend, and solve novel, complex problems without the use of words [5]. Assessment tools like the Raven’s Coloured Progressive Matrices (RCPM) are preferred in multicultural settings or rural areas where poor language skills are a barrier [5].

The objectives of this study were to assess the non-verbal intelligence in school-children from a rural setting and to study the relationship of nutritional status, nutrient (zinc, iron and folate) intakes and parents’ education with children’s non-verbal intelligence.

This cross-sectional study was carried out in 6-11 year old children from a randomly selected primary school in Karegaon, a rural area in Western Maharashtra, from mid June 2014 to end of July 2014. Children with known chronic disorders like diabetes, thalassemia and intellectual disability were excluded [6]. According to earlier reports of RCPM scores (70.65% children below average), considering a 4% margin of error and 5% significance level, sample size of 313 was computed [2]. Ethical approval was obtained from the Ethics Committee, Jehangir Clinical Development Centre. Written informed consent was obtained from parents.

Demographic data, socioeconomic status (SES) and parents’ education were elicited by structured questionnaires [7]. Height, weight and hemoglobin concentrations were assessed by standard techniques [8,9]. Anemia was categorized as mild (hemoglobin 11-11.4 g/dL) and moderate (hemoglobin 8.0-10.9 g/dL) [9].

Dietary intake was assessed by 24-hour dietary recall taken over three non-consecutive days. Nutrient intakes were estimated by the C-Diet software (a cooked foods database software) and were compared to the Indian recommended dietary allowances (RDA) [10,11]. Dietary adequacy was computed based on Indian RDA.

The study population comprised of 323 children (52.9% boys) with mean age of 8 (1.1) years and 89% belonging to middle SES. Anthropometric parameters and nutritional intakes were comparable and diets were deficient in both macronutrients and micronutrients. Mild anemia was detected in 2.3% and moderate anemia in 4.5% children. Table I depicts the distribution of RCPM scores and inter-category comparison of demographics.

TABLE I  Demographic Characteristics of Children According to the RCPM Scores

Comparably, in a study of Santal tribal children, RCPM scores of well-nourished children as well as of those from upper SES were found to be significantly higher than that of the poorly nourished children and those from lower SES, respectively [2]. The absence of association of RCPM scores with SES in our study can be explained by the relatively homogeneous socio-economic status distribution. However, we did observe positive though weak associations of paternal and maternal education with RCPM scores, with the latter demonstrating a stronger association. Schooling, more than household wealth, has been proposed to be a reliable assessment of SES and maternal schooling has been demonstrated to exert a strong influence on children’s cognitive functions [1]. The weak associations obtained between parental education and RCPM scores may be because other than parental education level, data related to important factors like parenting style and family interactions, which also have an influence on cognitive outcomes, was not collected by us.

It has also been demonstrated in previous studies in children that micronutrient intakes are positively associated with cognitive test scores. We observed that though diets of the study children were overall deficient in micronutrients, those whose diets had relatively higher amounts of zinc, iron and folate performed better in RCPM test. Sen, et al. [12] demonstrated that anemia negatively affected cognition in Indian adolescent girls and demonstrated an improvement in assessment scores with iron-folic acid supplementation. Serum folate levels have shown weak significant positive associations with cognitive test scores in the NHANES III data on 6-16 year olds [13]. Supplementation studies with zinc-rich foods have demonstrated positive effects on cognition in young, undernourished Indian adolescent girls [14]. However, we found poor associations of micronutrient intakes with RCPM scores in our study; this may possibly be because current dietary intakes may not have an association with long-term outcomes such as cognition.

This study being an observational study, only provides an insight into limited factors that are associated with non-verbal intelligence in school-children from a rural setting. Further studies are required to elucidate the mechanisms of association of different variables observed in this study with non-verbal intelligence in school-children. Also, long-term supplementation studies which consider factors such as parenting and family interactions are required.

Thus, in rural school-children, parent’s, especially mother’s education, children’s linear growth and dietary intakes of zinc, iron and folate may be important influencers of outcomes in non-verbal tests of intelligence.

Acknowledgements: We are grateful for the help and support of Neha Kajale and Sonal Palande. We are thankful to all the psychologists who administered the Raven’s CPM test and assisted with its interpretation. We also wish to thank the school principals, teachers and school staff.

Contributors: RM: data collection, analyses and drafted the initial manuscript; VHE: assisted with data collection, data analysis and manuscript revisions; SAC: conceptualized and designed the study, carried out the analyses, reviewed and revised the manuscript, and approved the final manuscript as submitted; VVK: conceptualized and designed the study, critically reviewed the manuscript, and approved the final manuscript as submitted; AVK: conceptualized and designed the study, reviewed and revised the manuscript, and approved the final manuscript as submitted. All authors approved the manuscript, are accountable for all aspects.

Funding: Rubina Mandlik was funded by a fellowship grant from the University Grants Commission (UGC), Government of India.

Competing interest: None stated.