Amanda Bynes has been using her Twitter account to lash out at everyone lately including Rihanna, Perez Hilton, Courtney Love, Jenny McCarthy and model Chrissy Teigen.

The latest victim of the 27-year-old actresses’ Twitter rants is former ‘N Sync member Lance Bass, according to E! Online.

Bass, who meet Bynes on the set of the 2005 film Love Wrecked, gave his insight on the former Nickelodeon star’s recent troubling behavior saying on Las Vegas radio’s Mark and Mercedes show Wednesday, “It’s one of those situations where obviously there’s some mental problems there and she’s not able to see that. We all are [able to see it].”

He also voiced his concern for the young star, saying: “I’m actually really scared for her, and I hope someone is able to get to her to give her the help she needs.”

On Thursday, Bynes discussed the singer’s remarks on you guessed it–Twitter.

“I ignored Lance Bass on twitter and now he is saying I have a mental illness. Sorry you’re an ugly ex boy band member w/ no talent or career,” she tweeted. “I haven’t spoken to Lance Bass in 11 years. To say I have a mental illness out of nowhere makes me lash out! You’re making me crazy!”

Bass responded by pointing out that Bynes’ recollection of how long they haven’t communicated for is outright wrong and how he thinks the person on her Twitter account isn’t really her.

He tweeted, “Ouch—The Amanda I know would never had said something like this to me—either this is a fake person or she really does have a mental illness. Way too sad. I reached out—all i can do” and later wrote, “Now I really don’t think this is Amanda—we shot Love Wrecked together 7 years ago and she was just at my bday party 3 years ago. Hmmm 11?”

Bass is not the only celebrity to weigh in on Bynes’ erratic behavior. Former child stars such as Matilda actress Mara Wilson, “Family Matters” star Jaleel White, “Silver Spoons” star Ricky Shroder, Alyssa Milano and Patty Duke have all expressed their concern, as well music mogul Russell Simmons and David Spade.

One person that is not concerned about Bynes is her DUI attorney Richard Hutton, who feels it is not warranted.

“I think [reports] are way exaggerated,” he told recently told People magazine. “I think Amanda’s fine. I have no problems with her whatsoever. She’s a fine client.”