It is ironic that an article in the January 21 issue on a study in the Journal of Developmental and Behavioral Pediatrics by Dr. Hallam Hurt proclaimed that "the data revealed that poverty has a severe adverse effect on cognitive development". Actually, the study appears to debunk an earlier, rashly proposed assertion that prenatal cocaine exposure significantly affects cognitive development.

The article’s assertion based on Hurt’s study is no more valid than the assertion drawn from the earlier study of prenatal cocaine exposure. This is because both studies have insufficient controls to draw any conclusions on cause. Thus, the article repeats the logical error of confusing correlation with cause and effect.

I hope that in the future such studies lead only to the proposal of multiple hypotheses to be tested in further investigations with more controlled variables, rather than to the proposal of single rash, and likely erroneous, assertions.

Joseph G. Lalonde, M.D.

Columbus, Ohio