Outes-Leon, I., Porter, C., & Sánchez, A. (2011). Early nutrition and cognition in Peru: A within-siblings investigation (IDB Working Paper Series N° 241). Inter-American Development Bank.

This paper examines the causal link between early childhood nutrition and cognition, applying instrumental variables to sibling-differences for a sample of pre-school aged Peruvian children. Child-specific shocks in the form of food price changes and household shocks during the critical developmental period of a child are used as instruments. The analysis shows significant and positive returns to early childhood nutritional investments. An increase in the Height-for-Age zscore of one standard deviation-keeping other factors constant-translates into increases in the Peabody Picture Vocabulary Test (PPVT) score of 17-21 percentof a standard deviation. The period of analysis includes the recent global food price crisis that also affected Peru between 2006 and 2008. This therefore is also a quantification of the nutritional and subsequent cognitive costs of food prices on the sample, which could be magnified in later years.