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Early malnutrition and parasitic infections reduce cognitive ability later in childhood

Johns Hopkins University Bloomberg School of Public Health

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 February 16 issue of The Lancet, suggests that efforts to improve cognitive function of school children 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, ScM, lead author of the study. Berkman conducted his research while studying epidemiology at the Johns Hopkins Bloomberg School of Public Health and submitted the research as his master's thesis. Berkman is now a medical 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, MD, professor of international health at the Johns Hopkins Bloomberg School of Public Health. 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 diarrhoeal 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 (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 with the G. lamblia parasite that causes diarrhea, one or more times per year scored 4 points lower on WISC-R than children that were not infected with the parasite. However, the researchers found no decrease in test scores among children with a history of diarrhoeal disease in general or diarrhea caused by Cryptosporidium parvum infection.

"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," explains Dr. Gilman.

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


The article "Effects of stunting, diarrhoeal disease, and parasitic infection during infancy on cognition in late childhood: a follow up study" appears in the February 16, 2002 issue of The Lancet and was written by Douglas S. Berkman, Andres G. Lescano, Robert H. Gilman, Sonia L. Lopez, and Maureen M. Black.

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

For more information, visit the Johns Hopkins Bloomberg School of Public Health on the Internet at

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