Stunted growth caused by chronic malnutrition during the first two years of life has an adverse affect on a child's cognitive ability later in childhood, according to researchers from the Johns Hopkins Bloomberg School of Public Health and the University of Maryland School of Medicine. The researchers also concluded that early infection with the diarrhea-causing parasite Giardia lambia might be associated with diminished cognitive function later in childhood.

The study, which appears in the Feb. 16 issue of The Lancet, suggests that efforts to improve cognitive function of schoolchildren in developing nations should focus on improving the nutrition and well-being of children early in life.

"With this study, we were able to track the children as they developed from infancy through age 9. Children with severely stunted growth at age 2 scored 10 points lower on cognitive tests than their peers, which indicates that the detrimental effects of malnutrition linger through childhood," explains Douglas S. Berkman, lead author of the study. Berkman conducted his research while studying epidemiology at the Bloomberg School of Public Health and submitted the research as his master's thesis. Berkman is now a student at the Robert Wood Johnson Medical School at the University of Medicine and Dentistry of New Jersey.

For the study, Berkman used data collected from an earlier nutritional study conducted from 1989 to 1991 by co-author Robert H. Gilman, professor of international health at the Bloomberg School. In the initial study, researchers followed 234 children near Lima, Peru, from birth to age 2. At the time, the children were monitored for growth development and incidents of diarrheal disease and parasitic infection. In 1999, Berkman tracked down 143 of the original study participants for further evaluation. The children were assessed using the Wechsler intelligence scale for children-revised, or WISC-R, which is a widely accepted test for measuring cognitive ability and intelligence.

After adjusting for socio-economic status and schooling, the researchers found that by age 9, children who were severely stunted in the second year of life scored 10 points lower on the WISC-R cognitive test than children with better development. The researchers also looked closely at the impact of diarrhea, which is both a cause and an effect of malnutrition. Children infected one or more times per year with the G. lamblia parasite that causes diarrhea scored 4 points lower on WISC-R than children who were not. However, the researchers found no decrease in test scores among children with a history of diarrheal disease in general or diarrhea caused by Cryptosporidium parvum infection.

Gilman says, "There is a high prevalence of stunted growth in children living in less developed countries. It is estimated to be as high as 40 percent in children younger than age 5. Our results can be used in designing intervention programs seeking to prevent the adverse effects of stunting later in life."

Adds co-author Maureen Black, professor of pediatrics at the University of Maryland School of Medicine, "This study illustrates the importance of attending to the nutritional needs of children under 3 years of age."

The research was funded by an ITREID grant and a grant from the Fogarty Foundation at the National Institutes of Health.