TLDR; prescription drugs
https://kffhealthnews.org/news/article/new-old-age-paula-span-falls-mortality-death-older-people-prescription-drugs/
>> prostate cancer
Yup. My FIL started falling after getting prostate treatment. BP medications cause it too.
Our gerontologist friend said it's one of the reasons it's worth bringing on a gerontologist at some point - docs treating prostate cancer and BP often don't have a holistic picture of life for an elderly person. As a gerontologist, he rates fall risk as a major risk and, depending on the status, going to a less effective treatment for prostate might be a minor risk comparatively.
>> gabapentin
Nephew was on that post-surgery and wanted to get off it as soon as possible because in his opinion he was unsafe to drive for at least 12 hours after (and he's a young man who races cars as a hobby)