(Digital Spy)
Updated: 2007-08-04 11:44

A psychologist has claimed that Britney Spears' erratic behaviour could be a result of Bipolar disorder.

The troubled singer raised eyebrows recently after becoming incoherent and vomiting on her dress during a photoshoot for OK! magazine.

She also reportedly tried to have her children’s teeth whitened and stripped to her underwear for an impromptu swim in the ocean.

Psychologist Dr. Robert Butterworth - who has not treated the star - said he thinks her meltdown may be caused by the mood condition, which is characterised by periods of depression and mania.

He told Us Weekly magazine: "Your energy level and emotions alternate between highs and lows, and that seems to have happened here."