Infections make you dumber, Danish study finds
A new study shows that those who have been hospitalized for infections have slightly lower IQs than average. Researchers in Denmark found records to 190,000 Danish men born between 1974 and 1994 who had taken IQ tests. (Denmark's mandatory draft requires males to take IQ tests when they sign up at age 19.) They found that roughly 35 percent of the sample had been hospitalized for infections before they took the test, and were 1.76 points below the average of men who hadn't been hospitalized. Researchers also found that those with five or more hospitalizations for infection were 9.44 IQ points below the average, suggesting that the more times a person had been infected, the lower their cognitive ability was. Infections of the brain have been known to lower cognitive scores, but researchers were surprised to see that both viral and bacterial infections (like those of the stomach, urinary tract and skin, and STDs like herpes) affected the brain also. How infections cause a decrease in cognitive ability is unknown, and it could be possible that those with lower IQs are genetically predisposed toward infection.