Relationship between childhood infections and measured intelligence.

The possibility that some of the common childhood infections lead to unrecognized impairments of neurological function was examined in 43 820 Birmingham children whose intelligence was assessed in the 11-plus examination. Mean verbal reasoning scores were lower for children who had had measles or pertussis than for those who had had neither of these diseases. However, since attack rates and measured intelligence are related inversely to social class, the lower scores of children with measles and pertussis may be due to class differences which are not eliminated completely by standardization for maternal age and birth order. Mean scores were a little higher for children who had had rubella than for those who had not, and it is suggested that this difference may be due to more frequent reporting of the disease by the more intelligent mothers.