Around the bend adjective – Informal or slang terms for mentally irregular. Mad and around the bend are semantically related. in insane topic. In some cases you can use "Mad" instead an adjective phrase "Around the bend".
The classic The Ren & Stimpy Show episode "Space Madness" ends with Commander Hoek, driven mad by... well, by space madness, brings Cadet Stimpy around the bend with him by ordering him to guard the History Eraser Button, with a very strict order not to let anyone touch it.