People with bipolar disorder are missing out on crucial early intervention because of lengthy delays in diagnosis.

An Australian study has found that, on average, people with bipolar are not diagnosed until six years after the onset of symptoms.

The delay in diagnosing bipolar is often longer for young people because their moodiness is sometimes mistaken for teenage angst.

Researchers at the University of New South Wales' School of Psychiatry analysed more than 9000 patients from 27 studies.

They found many patients experienced distressing symptoms for many years until receiving proper treatment for bipolar disorder - previously known as manic depression.