Belgium striker Christian Benteke, with his 14th league goal of the season, fired Villa into a first-half lead but the game changed in the first 15 minutes of the second half.
Henderson equalised on 47 minutes and Gerrard fired home a penalty on the hour to leave Villa stuck in the bottom three.
Reading prop up the standings on 23 points from 31 games, with Queens Park Rangers, who play away at Fulham on Monday, on 23 from 30. Villa have 30 from 31, with Wigan sitting just above the drop zone.
- Sports & Recreation