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Health affects minds

A Disturbing Link: Disease and Intelligence

Central to our work in global health has been the effort to reduce infectious diseases such as diarrhea and malaria in developing countries. Because these diseases no longer affect the rich world, they haven’t received the attention they should given their truly devastating impacts on poor communities, where they’re prevalent.

Infectious diseases in developing countries are important not only because of the tragic toll they take in human lives lost, but also because of the tremendous social and economic costs associated with them.

Recently I read an article in The Economist, which looks at growing evidence that disease and intelligence are connected in ways that are pretty shocking and troubling. Although more studies are needed, the evidence makes me even more convinced that we need to get after malaria and diarrhea – and many other diseases far too common in the developing world – in a big way.

Specifically, new research by University of New Mexico researchers has found that cognitive ability (IQ) is generally lower in places where infectious diseases are widespread, i.e., poor countries.

People are just now realizing this. It’s a huge scandal and yet another reason why it’s so critically important to fight infectious disease, which takes a huge toll on people’s ability to learn and climb out of poverty.

What’s going on is that fighting off parasites and microbes associated with things like diarrhea and malaria takes away energy that the body needs for brain development. This is especially true among children and infants. Newborns use almost all their metabolic energy for their rapidly developing brains. Analyzing IQ and epidemiological data from around the world, the UNM researchers found that the burden of infectious disease plays a much bigger role in depressing IQ than other possible explanations that have been talked about.

There’s also clinical evidence. For example, research in Uganda found that children who survive cerebral malaria, which affects more than a half-million African children every year, continue to suffer significant cognitive impairments, mainly memory and attention deficit, even two years later. The Ugandan researchers found that these children can be helped by weekly sessions where they use cognitive training software on PCs. But this is an expensive, intensive and only partially effective approach to a problem that could have been prevented to begin with.

The cognitive problems created by malaria are another strong reason why our foundation has made fighting it a priority. We’re trying to help develop a safe, highly effective and affordable malaria vaccine, while also supporting efforts to improve treatment, diagnostics and other malaria control measures.

Widespread infectious disease may even impair kids who don’t get sick themselves. Adults who are ill are less productive; farmers grow less food, for example. Less food means less energy available for their kids and their kids’ brain development. An article in The Lancet medical journal estimates that because of malnutrition, poverty and poor health, over 200 million children under five years are not fulfilling their developmental potential.

In the past, some people have suggested that poor countries are poor because the people there have lower IQs. But it’s really the other way around. Poverty breeds disease, which can affect brain development, which reinforces poverty. Improving global health is a way to break this cycle.

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