I was dismayed to read in the August 20 issue that "the case is becoming stronger that perinatal complications play a causative role in autism." The authors of the study did not state that perinatal complications are a causative factor in autism. They pointed out that there was an association between the occurrence of perinatal complications and the eventual diagnosis of autism in the involved children. The finding of an association between perinatal complications and autism has, in fact, led some to suspect that the ultimate cause of autism is also the cause of the perinatal complications, thus giving us another piece of information to use to find the actual cause.

There is a crucial difference between cause and association. The confusion of these two frequently leads to misinformation and misunderstanding by the public of scientific evidence.