What is the origin of the idiom "around the bend" and when to use it?

The origin of the idiom "around the bend" is uncertain, but it is believed to have originated in the early 20th century, possibly in American English. The phrase draws on the literal meaning of "bend" as a curve or turn in a road. This expression can be used to describe instances where individuals display signs of madness, extreme eccentricity, or unconventional thinking. It can be applied to situations where someone's behavior becomes increasingly bizarre or detached from reality.