What are the APA Style rules for emphasizing words in text?
According to the American Psychological Assocation (2010), "do not use quotation marks . . . to introduce a technical or key term. Instead, italicize the term" (p. 91). Accordingly, you can use italics in your text when first introducing a new key term, but only italicize the word the first time it is introduced. After that, present the word in your usual font. See "Using Italics for Technical (or Key) Terms" from the APA Style Blog for more information.
American Psychological Association. (2010). Publication manual of the American Psychological Association (6th ed.). Washington, DC: Author.