EFFECTS OF MALNUTRITION - MALNUTRITION AND COGNITION
In addition to reducing growth, malnutrition also impairs cognitive ability. Malnutrition during the period of most rapid brain growth (last trimester of pregnancy through the first 9-12 months of postnatal life) diminishes brain size, brain DNA content, myelinization (formation of the myelin sheath around a nerve fiber), cortical dendritic growth, and neurotransmitter content (chemicals that allow the movement of information from one neuron across the gap between it and the adjacent neuron). Some of these changes may be ameliorated by environmental enrichment.
A linear correlation between growth and developmental delays has been identified in children with protein-energy malnutrition. Similarly, malnourished international adoptees are more likely to be developmentally delayed than are better nourished children.
Numerous studies (but not all) find permanent reductions in cognitive ability after significant malnutrition in early childhood. Studies in Jamaica and South Africa show reduced IQ as long as 20 years after recovery from malnutrition. One study found that children sustain a loss of approximately 12.5 IQ points as long as 10 years after a single episode of malnutrition.