Two-thirds of Australians suffering clinical depression have used multiple antidepressants to manage their condition, the nation's largest study on depression has found.
More than 10,000 adults living with the mental illness have so far enrolled in the Australian Genetics of Depression Study and researchers have released some of the preliminary data.
Lead investigator Professor Nick Martin at the QIMR Berghofer Medical Research Institute says the data highlights that current treatments are far from perfect and there is a lot of room for improvement.
"About 30 per cent of people say that antidepressants work but a large proportion of those have had trouble with them in terms of side effects so they've had to swap prescriptions a number of times to actually find one that works for them," Professor Martin told AAP.
"In no way is this dissing the profession or the medications that are available at the moment, they are the best we've got," Prof Martin said.
Professor Ian Hickie from the Brain and Mind Centre at the University of Sydney says the data confirms what has been frustrating many in the field for a long time.
"We've reached the limit of our current knowledge of treating clinical depression," Professor Hickie said.
"Given our lack of diagnostic methods to predict different responses to antidepressants, or forecast the potential for intolerable side-effects, we are exposing those battling clinical depression, to trial and error, which is often slow to deliver significant benefits," Prof Hickie said.
"To date, we have failed to move effectively from the general principles of treating clinical depression, to much more personalised and targeted approaches that minimise risk to maximise benefit," he said.
Genetics is the key to fixing this problem, Prof Martin said.
The geneticist is urging more Australians living with the mental illness to enrol in the study that requires a total of 20,000 Australian study volunteers aged 18 and over.
"The link between genetics and clinical depression is very clear. Approximately 20,000 genes make up the human genome. Alterations in some genes cause clinical depression. But right now, we don't know what they are. What we do know, however, is how to find them.
"We just need a large enough study, performed the right way, to identify them," said Prof Martin.
It is hoped the "groundbreaking" research will lead to the identification of between 50 to 100 genes that influence a person's risks of developing depression.
"Only then, through cracking the genetic code of clinical depression, will we be able to develop new, and more effective, personalised treatments that target the problem directly," said Prof Martin.
To volunteer for the Australian Genetics of Depression Study, or to learn more people can go to: www.geneticsofdepression.org.au.