His personality changed. He turned into a big bully.

他性格变了，成了一个大坏蛋。

《柯林斯英汉双解大词典》

At the first trial in 1998, expert witnesses dismissed her lawyers' claims that surgery for a brain tumour had changed her personality.

在1998年的最初审判中，律师声称她的性格曾因脑肿瘤手术而改变，当时专家证人摈弃此说。

youdao

Somehow the rod that passed through his brain had changed his personality, and he was a different man.

那跟穿过他脑袋的棒子改变了他的性格，他完全是另一个人了。

youdao

I've not changed my personality, and it has not stopped me in progressing in my career.

BBC: Are women their own worst enemy when it comes to the top jobs?

What if it turned out that by enhancing intellectual ability, some other personality trait changed as well?

CNN: ASIANOW - TIME Asia | Brainteaser

Tommy said his personality also changed following the stroke.

BBC: NEWS | Health | Creative side unlocked by stroke