Jasmine Lennard, who met Lohan when she moved to LA, has suggested that drugs aren't the only source of her erratic behaviour.
Writing in the Sunday Mirror, she said: "I often wonder whether all her behaviour can be attributed to her addictions to drink and prescription drugs and her dabbling with cocaine.
"But I have concluded that - sober or not - Lindsay... is a real mean girl, a bad person and a bad friend. She is vacuous, self-consumed, spoiled and ugly inside."
She added: "She is entirely aware of the power she possesses over people. Her weapon is sex. I’m not saying she wants to have sex with everyone she meets - but I am saying that short, tall, black, white, man or woman... she will make you feel like she wants to. This is a game for her. It is also the behaviour of someone with chronically low self-esteem."
Lohan was recently sentenced to 90 days in jail for violating the terms of her probation.
