Is my memory deceiving me, or does someone in that quite literally end up half the person they used to be following a certain incident between a train and some tracks? If so, I do remember being quite shocked by that at the time, especially given when the film was made too (although it would have been nothing new of course, what with Catch-22 having got there first even earlier).
Robert Aldrich's a good general example for this thread; all his films are pretty gruelling stuff which were envelope-pushing in their time, not necessarily in terms of any explicit scenes or content but quite relentless in assaulting the senses in other ways, particularly psychologically. Even as ostensibly innocuous a subject for a plot as 'A Wedding' doesn't exactly make for pleasant, comfortable viewing in his film of the same title.