Having lived in the spotlight for 11 years Miley Cyrus, 19, is no normal teenager: before she could legally drive there were controversially sexy pictures of her plastered all over the internet, and at 15 she was voted one of Time’s 100 Most Influential People.

And now, after suffering a career crisis with her recent movie LOL flopping at the box office and no fresh music for the past four years, the newly engaged star – whose fiancé Liam Hemsworth is more in demand than ever – has been acting bizarrely, shaving her head, partying hard and sharing her every thought on Twitter.

All of which psychologists view as evidence of a personal “downward spiral”, while industry experts believe she’s trying to make herself “relevant by stirring up controversy” in an age when a career can be built on simple notoriety.

Britney-style meltdown

With over eight million followers, Miley’s one of the most popular stars to follow on Twitter, and the teen posts a constant stream of messages and photos of herself on the site, but is also quick to slam what she sees as “ignorant” criticism of her Tweets – largely, messages that disagree with her posts.

Her recent Tweets have included bragging about how she “has so much money she should start a bank”, as well as saying “To love is to suffer” after her engagement. But it was her recent change of hairstyle that really set the star off on a major Twitter-fest as she posted pics of her dyed and shaved new look, along with captions such as, “If you don’t have something nice to say don’t say anything at all. My hair is attached to my head no one else’s and it’s going bye bye :)”

And the actress has also taken to chatting to Charlie Sheen on the social networking site, with the troubled actor inviting her to hang out at his house via a tweet that was then quickly deleted.

Spotted partying hard in New York without 22-year-old Liam (whose been busy shooting films back-to-back), Miley was spied kissing a pal in the middle The Darby nightclub in an act an onlooker said was clearly “to get everyone’s attention” – and which has sparked rumours that her family and friends are set to stage an intervention, worried about the Can’t Be Tamed singer.

Still, some experts fear the teen’s incessant over-sharing of both her every thought and the plethora of photos of herself is a classic sign of “narcissism”, with one LA psychologist explaining that she seems to be “stuck in a set of compulsive behaviours that cry out for attention.”

Adding that Miley’s behaviour mirrors that of X Factor judge Britney Spears, who publicly shaved her head in 2007, an act that marked the beginning of serious mental health problems and a shocking meltdown.

“Miley Cyrus’ parade of unusual and provocative behaviour reminds me of Britney Spears’ downward spiral in the past,” he said. “The apparent recent marks on her wrist, the drastic haircut, and an undeniably fledgling career suggest to me that Miley is overwhelmed with anxiety, feeling lost and uncertain about her future.” Adding, “Her loved ones should keep a close eye on her in case her impulsive behaviour gets worse, potentially putting her at risk of self-harm.”

It's all a career strategy

“As an idol to tweens the world over, singer-actress Miley Cyrus, 15, is riding a huge tidal wave at the pinnacle of her career,” wrote former child star, Donny Osmond, in his tribute to her in Time’s 2008 100 Most Influential People list. “And this is as it should be. I hope she enjoys it. Within three-to-five years, Miley will have to face adulthood. As she does, she’ll want to change her image, and that change will be met with adversity.” And it was a warning that has appeared prophetic, as the former Disney star has proved unable to take her young fanbase along with her on her journey to adulthood.

“She’s doing what a lot of 19 year olds do: showing off her new look,” said Manhattan psychotherapist Jonathan Alpert, author of Be Fearless: Change Your Life in 28 Days. “Given the fact she is a celebrity, there’s also a secondary gain that is part strategic. Anything that draws attention to her sells her brand. The very nature of celebrities is that they’re showy.” And, in the Kardashian age of celebrity, sharing every aspect of her life may be viewed by her strategy team as the only way to maintain brand visibility as the work dries up.

“Miley’s incessant Twitpic-ing is part of her job, almost like attending red carpet events or filming movies,” insisted one Hollywood-watcher of the ‘new celebrity’. “She’s keeping her image out there – whether she overexposing herself is another issue – so people keep her in mind.”

Industry insiders have pointed out that this constant craving for attention could damage Miley’s health, with one saying, “She posts photos from every angle, much like we all do when we have our hair done. Only our mirrors don’t talk back. The mirror she’s using is an online audience that will throw **** back.”

And although she insists she’s “never felt so me in my whole life”, the barrage of abusive comments – par for the course on Twitter, just ask LeAnn Rimes – have left pals fearing it will be too much for fragile Miley to handle. “She should let up on the tweeting,” said one. “She gave it up once and she should realise that she needs to step away for a while. It does look like she’s going through something, but it seems more like normal insecurity and affirmation seeking than a breakdown.”