lose (one's) marbles

Translations
сходить с ума
After weeks of stress at work, he started to lose his marbles.
После недель стресса на работе он начал сходить с ума.
Definitions
To go crazy or become mentally unstable; to lose one's sanity or rational thinking.
Words
lose

verb
терять
one's

article or possessive pronoun
свои
marbles

noun
шарики