Ali Lohan may score a lot of perks thanks to big sis Lindsay – think nights out in Hollywood hotspots, Beverly Hills shopping sprees and the recent trip to Hawaii where the pair wore teensy bikinis and were photographed constantly.

Unfortunately, one thing the 15-year-old starlet isn't getting from Lindsay is a good role model who's making positive life choices. Experts say the sibling relationship could actually be harmful to Ali's mental health.

"If you have an older child who is breaking a lot of the rules and engaging in dangerous and risky behavior, this can have a negative impact on the younger child," said Dr. Eva Ritvo, psychiatrist and vice chair of psychiatry at the University of Miami School of Medicine.

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"Adolescents are trying to break away from their family and they don't always make the best choices. They're looking for role models other than their parents, and often turn to peers and older sisters, who can have a very powerful influence on the younger child," she said.

Impressionable Ali can hardly help but notice Lindsay's partying, stints in and out of rehab, and her skin-and-bones appearance. But how she reacts to those things could go one of two directions, experts say

Some teens with out of control older sibs may copy them, while others fall into the role of trying to protect loved ones from the person. "You either try to outdo or you become a caretaker," says Dr. Keith Ablow, psychiatrist and Fox News contributor, who founded the website www.LivingtheTruth.com.

"The course Ali is taking appears to be more in the direction of copying than in shrinking from the cameras and the revelry," he said.

Besides the risk of having Ali try to emulate an older sib who's engaged in some negative behaviors, there's the danger that she's not getting enough parental attention because so much of it is focused on Lindsay.

"When you are a sister of the woman the world watches and who is seemingly more heat than light, you can get lost in the attempt to get attention," Ablow said. "It's like sibling rivalry on steroids, and to step out of that kind of energy is like stepping out of a tornado and hoping to not get chewed up as you step out of it."

Psychologist Donna LaMar said that Ali could be helped if a caring adult steps in and offers guidance, support and perspective. That person does not necessarily have to be a relative in order to be effective, she said.

"It could be a teacher or in her case, maybe someone in the business," LaMar said.

"The person could just say to her, hey what are you doing? What are you searching for and what do you need in your life right now?" What's important for those close to Ali is to not give up, LaMar said.

"It's never too late," she said. "There is always a choice to be made."

For now, Ali, who was recently spotted holding Lindsay's hand as they left West Hollywood's Chateau Marmont together, appears to be choosing Lindsay.

She's in a tough spot, acknowledged Ablow. "Trying to get what you need as a 15-year-old girl can be a tall order when your sister is very famous and very unpredictable," he said.

"A 15-year-old should not have to be in the role or either caretaker or competitor, but she should be in a comfortable place where she can become an individual, where she can look at the world with security and choose what defines her.From:www.nydailynews.com