Round the bend means driven mad or completely irrational. That noise sends me round the bend.
To be driven round the bend is usually about something small repeated rather than anything serious. Round the bend is informal and affectionate, and nobody uses it about real illness.
1phraseround the bendDriven mad or completely irrational.
“Three weeks of that dripping tap sent him round the bend.”
round the bend is a phrase.
Practised in Idioms