Parenthetical Initialisms

An e-mail exchange from June 2003 with the editor of the Chicago Manual of Style.

Q: Here’s the sentence “The educators in these schools are pushing a drug called Ritalin on students they diagnose with attention deficit disorder (A.D.D.).”

Must I use the initialism as above (in parentheses immediately after the phrase) before I use the initialism later in the essay? For example, if I want later to refer to “attention deficit disorder” as A.D.D., must I previously have referred to it as A.D.D. in conjunction with spelling out “atten-tion deficit disorder”?

A: This is a judgment call. If you are confident that your audience will know what A.D.D. refers back to, then you may choose to dispense with the hoop-jumping step of presenting the parenthetical initialism at first mention of attention deficit disorder. A.D.D. certainly would be a candidate for this looser treatment. Then there are initialisms that have become words in and of themselves—like CEO—and need not be introduced in any manner.