You wouldn't have a link to that research?
The only scientific research I could find is Nick Yee's from around 2004:
https://www.gamasutra.com/view/featu...e_.php?print=1
and
http://www.nickyee.com/daedalus/gate...ographics.html
In 2004 the average age of a mmorpg-gamer was 26. Interesting enough female players are considerably older than male.
Whether the average has gone or down since then would be intereting. I haven't found anything since that study.
My personal opinion is the average wow-player is older today. But that is my pulled-out-of-the-ass-number.