"It has a whole bunch of other things surrounding it, but it creates depressive symptoms."

According to SANE Australia, up to 4 per cent of Australians will develop BPD at some point in their life, with the symptoms usually manifesting in late adolescence.

Sufferers have trouble managing their emotions and impulses, and can also struggle to maintain a stable self-image.

The causes of BPD are not well understood, although they are believed to be a combination of biological and lifestyle factors.

Ms Collett said despite her diagnosis being relatively simple compared to other mental health issues, it was "frustrating" that there still wasnt a clear diagnosis and treatment for many sufferers.

Its hoped that new research from QIMR Berghofer Medical Research Institute could help change that, with scientists there identifying key areas on the human genome with direct links to depressive symptoms.

Senior study investigator Professor Eske Derks said the research uncovered seven distinct regions on the human genome with links to symptoms.

"We identified, for the first time, three genetic regions related to sleep problems, two for anhedonia [a loss of interest or pleasure in life], one related to changes in appetite, and one for depressed mood," Professor Derks said.

Overall, about one in 11 people, or 9 per cent of Australians, reported having depression or depressed feelings in 2014-15, according to figures from the Australian Bureau of Statistics.

The QIMR findings provide insight into why the symptoms of depression can vary hugely between patients, and they point the way to more targeted therapies.

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"In some patients, depression will manifest as a reduced appetite, while for others, there will be increased appetite," Professor Derks said.

"So normally if youre looking for the genetic risk factors for depression, you tend to collapse all of these symptoms together, even though they can be quite different from patient to patient."

Professor Derks said being able to accurately assess exactly what genes were in play for individual patients meant they would be able to get tailored treatment instead of the current method of "trial and error", where patients are prescribed the most common medication and then put on other drugs if that fails.

Ms Collett said it would be a comfort going forward to have a more certain diagnosis.

"Im naturally curious about my own health situation, so it would be really good to know the underlying reason why I have it. Was it genetics? Was it something that happened when I was a kid? Who knows?" she said.

The study, which examined genetic data and self-reported symptoms from 150,000 people from the UK Biobank, has been published in the journal Psychological Medicine.

Stuart Layt covers health, science and technology for the Brisbane Times. He was formerly the Queensland political reporter for AAP.

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Clear link between genetics and depressive symptoms uncovered - The Age