Amanda Bynes struggling with mental illness?

The former child star has been spotted displaying signs of mental illness, reported New York Daily.

"She came to the gym on Thursday looking dazed and began speaking with herself - making comments and then answering them back," a source said.

"When Byne was on the elliptical trainer, she would stop suddenly and start laughing hysterically for no reason," another source said.

Similarly, some of her neighbours have also voiced their concern over the behaviour of the 26-year-old starlet, with some mentioning that they have seen her having long conversations with inanimate objects whilst in her garden.