Malnutrition can affect cognitive function

Chronic malnutrition in infancy could lead to poor cognitive function in children at nine years of age, according to a study of Peruvian children published in The Lancet.

The research also concluded that early infection with the diarrhoea-causing parasite Giardia lambia​ might be associated with diminished cognitive function later in childhood.

A team from the University of Medicine & Dentistry of New Jersey led by Douglas Berkman assessed the effect of stunted growth - a key indicator of malnutrition - diarrhoeal disease, and parasitic infections during infancy on cognitive function in late childhood.

"With this study, we were able to track the children as they developed from infancy through to the age of nine. Children with severely stunted growth at two scored ten points lower on cognitive tests than their peers, which indicates that the detrimental effects of malnutrition linger through childhood,"​ Berkman said.

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 Johns Hopkins Bloomberg School of Public Health.

In the initial study, researchers followed 234 children near Lima, Peru, from birth to age two. 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), a widely accepted test for measuring cognitive ability and intelligence.

After adjusting for socio-economic status and schooling, the researchers found that by age nine, children who were severely stunted in the second year of life scored ten points lower on the WISC-R cognitive test than children with better development.

The researchers also looked closely at the impact of diarrhoea, 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 diarrhoea scored four 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 diarrhoea 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 per cent in children younger than age five. Our results can be used in designing intervention programmes seeking to prevent the adverse effects of stunting later in life,"​ said Dr Gilman.

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