Justin Bieber's antics, a sign of the crushing power of fame?

Canadian pop star Justin Bieber'sstring of recentantics could signal that the singer is falling victim to the pressures of fame.

Entertainment agent Jason Furman, with the Feldman Agency, assumes the high-stress level the young man is dealing with is contributing to his behaviour.

"He is only a kid who was forced to grow up quickly in order to achieve the success he has," Furman said. "Trying to live your life while being scrutinized under the public eye can be hard for someone at any age."

Bieber, who's been plagued by problems during the most recent stretch of his Believe tour, had his Lisbon show cancelledon Tuesday "due to unforeseen circumstances," according to a statement on the concert venue's website.

The cancellation comes after atough few days for the 19-year-old pop phenomenon from Stratford, Ont.

During one of his performances at the O2 arena in London, he lost his breath and collapsed backstage. He was given oxygen and was hospitalized for a brief time.

The pop star was also involved in an expletive-filled spat with paparazzi, forcing his security guard to pull him back from a possibly more serious altercation.

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He also had a confrontation with a bouncer at a London nightclub on his March 1 birthday.

'He's only just turned 19 and he's still learning to cope with the pressures of fame. But it's worrying.' Kathy Bieber, Justin's grandmother

Clinical psychologist Donna Rockwell, who co-wroteBeing a Celebrity: A Phenomenology of Fame, says that the stress of celebrity is extreme and also breeds an environment that is not conducive to self-awareness.

"One of the greatest stresses is fame. It's tremendously stressful to be famous, to have to be on in public every second," said Rockwell,adjunct professor at the Michigan School of Professional Psychology. "Its a very lonely, isolating and mistrustful place.

"We, as a society, so hunger for our own connection and glimpse of fame that just being around this famous person is enough for us to send our integrity to the devil and when we feel like saying 'You are really being out of line,' we don't."

Rockwell saysthose people ina celebrity's life often become yes peoplethat is, those who no longer act as a reflectionof who they truly are.

Shecited psychologist Robert Millman's theory of "acquired situational narcissism" as an example of what happens to those who become so well known.

The theory is that when the world and the people closest to a famous person start over-praising that person and fail to accurately reflect reality back at them, "the celebrity stops learning how to be in the world with other people. They are so used to everybody looking at them that they forget how to go back out and how to share equal responsibility in a relationship," she said.

Young and powerful

This disconnect fromreal life can be particularly common and dangerousfor young celebrities, some analysts say.

According to psychologist Dr. Linda Papadopoulos,the constant praise and ability to get away with everythingbreeds further entitlement issues and subsequently more behavioral problems.

"Its very hard to have 100 people around you telling you how wonderful you are all day, and not believe it," said Papadopoulos, who frequently works in television in the U.K.

"Especially if you are young, your sense of entitlement also becomes bigger. Being a celebrity today is like being Caesar in Roman times. You get everything for free and there is no sense of proportion."

A horde of other young celebrities have had similarand biggerdramatic moments and personal struggles in the wake of endless media attention.

In 2007, for example,Britney Spears lost custody of her children, shaved her head and entered rehab facilities more than once. She was recorded beating up an SUV with a baseball bat.

Actress Lindsay Lohan has had an endless string of troubles the past few years.Earlier this year,shepleaded not guilty to lying to police, reckless driving and obstructing officers from performing their duties. She was previously sent to jail and placed under house arrest.

Bad influences

In Bieber's case, the teen's grandparents, George and Kathy Bieber, recently spoke out about their grandson's latest escapades, saying they were shocked butreassured that the star's heart is in the right place.

"I don't think for one moment this is all about him being a bad boy," Kathy Bieber said, according to Britain's Sunday Express newspaper. "He's only just turned 19 and he's still learning to cope with the pressures of fame.

"But it's worrying. You read all sorts of things about him partying and he needs to understand some of those so-called friends probably don't have his best interests at heart. Justin is a sweetheart. He just needs to be kept away from unsavoury people who want to bask in his limelight and lead him astray."

How to cope?

To cope with stardom at a young age, Rockwell says it is crucialto have a strong support system.

"They need grounded people who understand the important things of life and try to make sure that the famous person keeps their eye on the prize of what matters."

Furman says that for Bieber, specifically, his managers and security need to ensure his safety and well-being.

"His manager needs to have that hard conversation with himcan he handle the pressure? Does he need a break?" Furman said."When on tour it's on the tour manager and lead security to either watch an act or keep that artist in check.

"But at the end of the day you can only babysit so muchthe artist needs to play ball as well."