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

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

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

Researchers at UNSW's 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.

Bipolar disorder is a condition that can cause severe mood swings. The high moods, or periods of elation, are called mania or hypomania, and the low mood is called depression.

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

"This is a lost opportunity because the severity and frequency of episodes can be reduced with medication and other interventions," said psychiatrist Matthew Large, who led the study published in the Canadian Journal of Psychiatry.

Unfortunately stigma is still one of the reasons why diagnosis can take so long, said Prof Large.

Other common barriers to diagnosis include costly and hard to get treatment, confusion about the symptoms and misdiagnosis.

"In an era of fifteen-minute medicine, I think misdiagnosis can occur," Prof Large said.

That said, it's not an easy diagnosis to get right or treat.

"Getting a diagnosis of bipolar disorder, particularly when it's mild, involves interviewing family members, seeing the patient repeatedly and talking over things from the past carefully."

Prof Large concedes there are no easy answers to reducing the delay in diagnosis, but reducing stigma would certainly help.

"Mostly patients with bipolar disorder come from all walks of life, they're often quite intelligent, hard-working and very nice, and they're not dangerous but I think there is still stigma about any mental illness."

Having bipolar disorder does not have to mean a life-long regime of taking drugs with lots of side-effects, says Prof Large.

There are a whole variety of things a person can do early on in the course of their condition that might help their prognosis.

These include keeping a tight reign on illicit substance use, exercise, developing stress management strategies and keeping educated on the disorder.

The researchers are calling for a more consistent approach to recording the onset of symptoms of bipolar disorder and for professionals to start thinking about prevention and early intervention.

"What we should be looking at is what strategies we can develop to identify people who are very likely to go on to develop bipolar disorder and what benign treatments are there that can prevent it."

"I think in the early stages we really need to concentrate more on non-pharmacological methods," said Prof Large.