Answered By: Katie Hutchison Last Updated: Oct 14, 2016 Views: 1768
The first time you introduce the topic you will want to write out the entire word, followed by parenthesis with the initials inside. For example:
Soliders returing from Vietnam faced Post-traumatic stress disorder (PTSD) at alarming rates...
After you introduce the topic you can simply refer to it after as its initials (in capitals).