"Studies indicate that some cultures may be more sensitive to this phenomenon than others; one study found that there is little evidence that people undergo midlife crises in Japanese and Indian cultures, raising the question of whether a mid-life crisis is mainly a cultural construct."
Japanese salarymen often undergo a crisis when they retire and suddenly find themselves with tons of time and nothing to do. Not exactly midlife, but it's of a similar vein.
I thought this was interesting.