The ‘Easy A’ actress – who found fame on kids channel Nickelodeon - is said to detest her fellow former child star and often rants about Lindsay.
A source told Us Weekly: “She obsessively hates Lindsay. She rambles about ‘that bitch Lindsay’ all the time.”
The 26-year-old star has suffered a string of setbacks recently including being charged with driving on a suspended licence and having her car impounded.
She was also involved in two bizarre episodes last month, locking herself in a store changing room for nearly two hours and refusing to come out and stripping off during a gym class and friends say her parents don’t know what to do as Amanda has cut contact with everyone.
The insider explained: “Amanda shut them out and isn’t speaking to them. She is doing everything on her own. She has no direction.
"Amanda is spiraling out of control. She won't accept help from anybody . . . She's completely lost."
Lindsay’s mother Dina Lohan recently offered some advice to Amanda’s parents, saying: “Just be around. ... It's hard when your daughter's not, you know, over 18, and you want to let them go ... and they want to, you know, feel like they're in control of themselves. So it's a very strategic place for a parent to be, but she'll be OK."