What insane asylums taught us.

• Author: Patterson, Paul
• Position: Medical Research - Relationship of influenza viruses to psychosis

ALTHOUGH the Spanish flu pandemic lasted for only a year, its dark legacy still haunts us. The year 1918 saw the appearance of the novel strain of influenza virus called H1N1, which caused the most widespread and lethal flu infection in recorded history. As many as 100,000,000 people died worldwide. It killed more Americans in one year than died in all the wars of the 20th century. This virus especially was lethal for young adults, and particularly pregnant women. Interestingly, this also was true of the pandemic virus of 2009.

Because of the work of Jeffrey Taubenberger and colleagues at the Armed Forces Institute of Pathology in Washington, D.C., we now know quite a bit about the 1918 virus. Taubenberger and Ann Reid used tissue that had been preserved in formaldehyde and paraffin from soldiers who died of the flu in 1918, and Johan Hultin retrieved tissue from Eskimos who died of the flu that year and were buried in the permafrost, which preserved the virus. Sequencing the genes of this lethal virus has revealed that it probably was derived from an influenza virus that infected birds and, through mutation, became able to infect mammals such as pigs and people.

This remarkable virus still casts its ominous shadow today: its descendants have continued to cause pandemics or global outbreaks such as those in 1947, 1951, 1957, 1968, 1997, and 2003. The global pandemic in 2009 was caused by a fourth-generation descendant of the bird-swine-human influenza virus of 1918.

Far less appreciated, however, is another sinister, decades-long legacy left by this virus. A graduate student at Columbia University and the National Bureau of Economic Research, Douglas Almond, used a remarkably simple method of uncovering the continuing human costs of the 1918 pandemic. In addition to the obvious effects on families from the loss of mothers or fathers, there were hidden effects on the fetuses gestating at the time the pandemic swept through the U.S. Some of those effects did not become clear until the fetuses became adults. Using the socioeconomic data collected each decade by the Census Bureau, Almond discovered that the offspring of women who were pregnant precisely during the time the flu came through their area grew up to have lower income, socioeconomic status, and educational attainment than those who had been gestating just before or after the pandemic.

These effects suggest that the virus affected fetal brain development. Other data indicates that...