Disease, intelligence and development are linked

There is an interesting article in the current issue of The Economist. It reports on scientific findings that link disease, intelligence and the economic development of a nation. I guess we all suspected as much. But we now have scientific findings that seem to indicate parasites and pathogens may explain why people in some parts of the world are more intelligent than those in others.

The article made me remember my late father. Right out of medical school, he chose to specialize in parasitology, microbiology and infectious diseases. After WWII, he went off to Tulane University in New Orleans to get his masters in public health specializing in Tropical Medicine. His peers took specializations in cardiology and other such fancy fields for more affluent societies that made them financially well off. My father happily remained a middle class university professor for the rest of his life.

I recall the many conversations we have had as I accompanied him on provincial trips whenever he was invited to conduct post graduate training courses for community doctors all over the country. He didn’t minimize the importance of the more financially rewarding specializations but he thought more Filipino doctors should have followed his footsteps and learned more about how to treat tropical diseases.

It was from him that I first heard the word morbidity. He used it when discussing statistics that showed the portion of our population who are unable to maximize their economic potential because of disease. Sometimes it is as simple as having intestinal parasites or being afflicted with malaria or amebiasis. Heart disease and cancer may attract a lot of attention among well off policymakers but a lot of our people are suffering from easily preventable and curable illnesses.

This article should be must reading for the new Health Secretary, the new NEDA Chief and P-Noy himself. It would give them good insights on how to approach the delivery of essential social services in the light of limited resources. It would seem from the article that it may be great to pour a big part of the budget to education, but that would have been money down the drain if the pupils are unable to learn effectively because they are infected with parasites and other common tropical diseases. Health appears to top education as a priority in this sense.

My father would have loved reading this article from The Economist. Human intelligence, The Economist reports, is higher, on average, in some places because they have effectively managed infectious diseases. This week, The Economist reports, a group of researchers at the University of New Mexico suggests that the control of infectious and tropical diseases is crucial to a country’s development in a way that had not been appreciated before.

Places that harbor a lot of parasites and pathogens not only suffer the debilitating effects of disease on their workforces, but also have their human capital eroded, child by child, from birth, The Economist reports. The suggestion was made by the scientists in the Proceedings of the Royal Society.

They note that the brains of newly born children require 87 percent of those children’s metabolic energy. In five-year-olds the figure is still 44 percent and even in adults the brain—a mere two percent of the body’s weight—consumes about a quarter of the body’s energy. Any competition for this energy is likely to damage the brain’s development, and parasites and pathogens compete for it in several ways.

Some of these parasites feed on the host’s tissue directly, or hijack its molecular machinery to reproduce. Some, particularly those that live in the gut, stop their host absorbing food. And all provoke the host’s immune system into activity, which diverts resources from other things.

The inverse correlation that the group calculated between a country’s disease burden and the average intelligence of its people is impressive, The Economist reports. “They estimated the disease burden from World Health Organisation data on DALYs (disability-adjusted life years) lost caused by 28 infectious diseases. These data exist for 192 countries.

“The intelligence scores came from work carried out earlier this decade by Richard Lynn, a British psychologist, and Tatu Vanhanen, a Finnish political scientist, who analysed IQ studies from 113 countries, and from subsequent work by Jelte Wicherts, a Dutch psychologist.

“At the bottom of the average-intelligence list is Equatorial Guinea, followed by St Lucia. Cameroon, Mozambique and Gabon tie at third from bottom. These countries also have among the highest burden of infectious diseases.

“At the top of the list of countries with the highest average intelligence is Singapore, followed by South Korea. China and Japan tie in third place. These countries all have relatively low levels of disease. America, Britain and a number of European countries, follow behind the leaders.”

We scored 86 in IQ and 3.43 for disease burden. In comparison, here are the scores for our Asean peers: Thailand, 91 IQ, 3.66 disease burden; Indonesia 82 IQ, 3.79 disease burden; Malaysia 92 IQ, 3.21 disease burden and Singapore, 108 IQ and 2.67 disease burden.

They tried to eliminate other possible explanations for IQ level like income, education, low levels of agricultural labor (which is replaced by more mentally stimulating jobs), climate (the challenge of surviving cold weather might provoke the evolution of intelligence). By careful statistical analysis, the scientists showed that all of them either disappear or are reduced to a small effect when the consequences of disease are taken into account, according to The Economist.

“There is direct evidence that infections and parasites affect cognition. Intestinal worms have been shown to do so on many occasions. Malaria, too, is bad for the brain. In the view of scientists, it is the various bugs that cause diarrhea which are the biggest threat. Diarrhea strikes children hard. It accounts for a sixth of infant deaths, and even in those it does not kill it prevents the absorption of food at a time when the brain is growing and developing rapidly.”

The scientists predict that “as countries conquer disease, the intelligence of their citizens will rise. A rise in intelligence over the decades has already been noticed in rich countries. It is called the Flynn effect after James Flynn, who discovered it. Its cause, however, has been mysterious—until now. If the lead scientist of this study is right, the near-abolition of serious infections in these countries, by vaccination, clean water and proper sewerage, may explain much if not all of the Flynn effect.”

In effect, the study suggests that different levels of economic development are due to a country’s health situation. It suggests that a country’s “lack of development, and the many health problems this brings, which explains the difference in levels of intelligence. No doubt, in a vicious circle, those differences helps keep poor countries poor. But the new theory offers a way to break the circle…” In other words, the study “will have done the world a good turn by providing policymakers with yet another reason why the elimination of disease should be one of the main aims of development, rather than a desirable afterthought,” The Economist concludes.

I know what my father would say… I told you so.

Wang wang

From my colleague, Ichu Villanueva.

Reporter: “Mr. President, mukhang tahimik ngayon ang kapatid nyong Kris!”

Noynoy: “Di ka ba nakinig sa speech ko? Pinatigil ko na ang wang wang!”

Boo Chanco’s e-mail address is [email protected]