lose (one's) marbles

lose (one's) marbles

To be or become mentally deficient, incompetent, or deranged; to become of unsound mind. My poor grandmother started losing her marbles after she had a stroke. I've been so sleep deprived lately that it feels like I've lost my marbles!
See also: lose, marble
Farlex Dictionary of Idioms.

lose (all) one's marbles

 and lose one's mind
Fig. to go crazy; to go out of one's mind. What a silly thing to say! Have you lost your marbles? Look at Sally jumping up and down and screaming. Is she losing all her marbles? I can't seem to remember anything. I think I'm losing my mind.
See also: lose, marble
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

lose one's marbles

see under have all one's buttons.
See also: lose, marble
The American Heritage® Dictionary of Idioms by Christine Ammer.

lose your marbles

INFORMAL
If you lose your marbles, you become crazy. At 83 I haven't lost my marbles and my memory is, thank God, as clear as it ever was. People are talking about him as if he's lost his marbles. Note: You can also say that someone has all their marbles, meaning that they are not crazy. He's in his eighties but he clearly still has all his marbles.
See also: lose, marble
Collins COBUILD Idioms Dictionary, 3rd ed.

lose your marbles

go insane; become irrational or senile. informal
Marbles as a term for ‘a person's mental faculties’ probably originated as early 20th-century American slang. The underlying reference is apparently to the children's game played with multicoloured glass balls.
1998 Spectator At least, that is how I recall the event, but I am losing my marbles.
See also: lose, marble
Farlex Partner Idioms Dictionary

lose your ˈmarbles

(informal) become crazy or mentally confused: They say the old man has lost his marbles because of the strange things he’s been saying, but I’m not so sure.
See also: lose, marble
Farlex Partner Idioms Dictionary

lose (all) one’s marbles

tv. to become crazy. (see also have all one’s marbles.) Have you lost all your marbles?
See also: all, lose, marble

lose one’s marbles

verb
See lose all one’s marbles
See also: lose, marble
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions
See also:
  • lose all one’s marbles
  • lose marbles
  • lose one’s marbles
  • lose one's marbles
  • lose your marbles
  • lose (one's) buttons
  • lose one's buttons
  • lose (one's) mind
  • lose one's mind
  • lose your mind