Saw this movie at a drive-in in English in the Midwest USA about younger people becoming the empowered society and they gathered up the elderly and kept them in a sort of gated place and they drugged all the elderly people to keep them happy…the younger people were in charge…
Sounds like the plot of Wild in the Street: http://www.imdb.com/title/tt0063808/.
Poster confirmed via email this was the one she was looking for so I’m marking it solved.