Fears that swine flu can attack unborn

July 26, 2009
From the Sunday Times


The H1N1 flu virus can damage the developing brains of unborn offspring, scientists have found.

They discovered that the virus changes the workings of genes that control fetal brain growth and development. Some of those genes have been implicated in mental disorders.

“Prenatal viral infection led to altered gene expression in the hippocampus, including autism and schizophrenia candidate genes,” said Hossein Fatemi, a neuroscientist at the University of Minnesota medical school, whose research paper details the results.

Fatemi’s research was carried out entirely on mice so the results need to be interpreted cautiously in terms of their implications for humans.

It was, however, prompted by other epidemiological evidence suggesting that children born to women who have suffered flu infections during pregnancy are at increased risk of schizophrenia and possibly autism too.

It reinforces existing advice that pregnant women should do all they can to avoid infection with the virus.

In the study Fatemi, his colleagues at Minnesota, and others at the Johns Hopkins University medical school, infected female mice with human H1N1 virus halfway through their pregnancies, which were then allowed to come to term.

The scientists then examined how the brains of mice born to infected animals had developed, compared with those whose mothers had stayed healthy throughout pregnancy.

They used magnetic resonance imaging to study each animal’s hippocampus. This part of the brain plays a crucial role in memory formation and emotional control and abnormalities are commonly found in people with schizophrenia and autism.

Fatemi said mice exposed to H1N1 as a fetus had a reduction in their hippocampus of up to 14 per cent. He said: “This is consistent with the observed reductions of hippocampus in subjects with schizophrenia and autism.”

The researchers also used DNA assays to find out which genes were over or underactive in the brains of mice that had been infected.

In their report, published in European Neuropsychopharmacology, they list more than a dozen genes whose workings seem to have been changed by the flu virus.

Fatemi said: “A dose of human influenza virus (H1N1) led to altered expression of many brain genes in the hippocampi of the exposed mouse offspring. These changes are in many cases similar to what has been observed in neuropsychiatric disorders, specifically autism and schizophrenia.”

Trevor Robbins, professor of Cognitive Neuroscience at the University of Cambridge, said the hippocampus was a particularly sensitive part of the brain and appeared to be strongly involved in the development of schizophrenia.

“There is a hypothesis that viral infection during pregnancy is linked to the development of mental disorders in offspring.

“Perhaps the best evidence is the influenza epidemic that hit the West Indies in 1958. There was an increase in schizophrenia among people whose mothers were affected during the second trimester. So there is a link between schizophrenia and infection, but with autism it is more controversial.”

Robbins said the new research simply reinforced existing advice. He said: “Pregnant women should do their best to avoid all infections, especially flu.”

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