I'm sure there is lots to be find if you dig into the research papers, but as you noticed there isn't much within 5 minutes of Googling.
Modern multi-touch user interfaces in smartphones and tablets seem to be especially successful with people that have very little experience with "regular" computers (e.g. small children and elderly).
The metaphors used in WIMP user interfaces in desktop operating systems are really disconnected from the physical world. They're abstract and indirect. If you haven't learned what a scrollbar is and does it will be quite foreign, as such a thing doesn't exist in the physical world.
Touch interfaces are all about direct manipulation: push the page up and it will go up exactly as much as you've pushed it. In that sense touch user interfaces are usually more intuitive.
However, how you do understand that the text is not simply cut off and that you can push the screen up to see more of it? You can usually expect users to have learned to recognise these situations and how to scroll. If your app runs on a smartphone, you can assume that users will have learned common patterns of the OS, like buttons, icons and scrolling.
However, in your case it's probably best not to make any assumptions. Some suggestions:
- Tutorialize the hell out of it with onscreen help and introduction videos. I kind of expect elderly will prefer to take their time to learn how to use something.
- Add a button (people are pretty good about recognising buttons as long as it's not flat-design) that says "show more text". Understand the user's task and offer clear support for it.