The 1972 film Images
is a good one. It tracks a character who is apparently schizophrenic. In a way, the viewer sees the action unfolding through the eyes of the main character-- at times, the plot is confusing in such a way that it is difficult to disentangle fantasy from reality. Narration and music are also used somewhat subtly and effectively to put the viewer in the 'schizophrenic' mood.
Here's a plot summary from IMDB: