A guinea pig study has found that newborn guinea pigs subjected to moderate vitamin C deficiency had 30% fewer hippocampal neurons and markedly worse spatial memory than guinea pigs given a normal diet. For several reasons the neonatal brain is thought to be particularly vulnerable to even a slight lowering of the vitamin C level. Vitamin C deficiency is very common in some parts of the world, and even in wealthy nations occurs in an estimated 5-10% of the adult population.
Vitamin C deficiency impairs early brain development
Reference
Tveden-Nyborg, P., Johansen, L. K., Raida, Z., Villumsen, C. K., Larsen, J. O., & Lykkesfeldt, J. (2009). Vitamin C deficiency in early postnatal life impairs spatial memory and reduces the number of hippocampal neurons in guinea pigs. Am J Clin Nutr, 90(3), 540-546. Retrieved from http://www.ajcn.org/cgi/content/abstract/90/3/540