Repeated bouts of diarrhoea and IQ

Repeated episodes of severe diarrhoea in early childhood can have permanent effects on brain development. Children who suffer serious and ongoing episodes of diarrhoea during the first two years of their life perform less well than other children on tests of intelligence between 5 and 10 years later. Previous research has shown that children who suffer from severe diarrhoea early in life tend to enter school later and are older than their classmates. They also perform worse in tests of non-verbal intelligence. Researchers from the University of Virginia, USA, followed 73 children, recording their health before 2 years of age and their performance on tests of intelligence between 5 and 10 years later. During the intelligence tests, children were asked to list as many words that fit into a certain category - such as, a type of fruit - within one minute, or to list as many words they could think of that began with a particular letter.
It was found that children with a history of severe diarrhoea before the age of two performed less well than others in the word category test, but similarly to others when listing words that begin with the same letter. According to the researchers, the brain undergoes rapid development during the first two years of life. Hence, if a child is experiencing chronic diarrhoea during that crucial stage, he may become dehydrated and thereby experience a decrease in blood flow to the brain, or may fail to absorb enough dietary nutrients to feed his developing mind. Easing the burden of chronic childhood diarrhoea involves improving water, sanitation, basic nutrition and the healthcare system. The results suggest that repeated episodes of childhood diarrhoea - a feature of many developing countries- could be detrimental to the brain power of a nation's future adult population, influencing the country's workforce, wealth and productivity. The study findings apply only to children who suffered repeated bouts of severe diarrhoea early in life as a result of poor sanitation and nutrition, and not to the majority of children in developed countries, who are well-nourished and experience occasional episodes of diarrhoea.

COMMENT