Hopes that medication could be tailored specifically to individual sufferers of depression have been boosted by an international study involving Australian research that identified dozens of links between specific genes and depression.
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Previous research conducted at the University of Queensland was used as part of a project co-ordinated by the University of Edinburgh that looked at 2 million people around the world.
The study, published in the journal Nature Neuroscience on Tuesday, identified 269 genes associated with depression, many of which are involved with the structure of synapses and the passage of nerve impulses through the brain.
Dr Maciej Trzaskowski from the University of Queensland, whose research formed part of the study, said the findings opened the door to developing new drugs to treat depressive disorders.
“The current drugs we have, the antidepressants, they are only effective in around 30 per cent of patients,” Dr Trzaskowski said.
“So the more we learn about the complexity and all the different genes that influence depression, we can potentially start to look at better therapies.”
Dr Trzaskowski said the study, the largest of its kind, could also eventually allow doctors to tailor treatment to specific patients, avoiding the potentially dangerous period where they try out multiple medications to see which one works for them.
“Unfortunately the current drugs that are available are a little like a sledgehammer, where it has a massive effect on everything,” he said.
“So if we can understand how different genes interact with each other, that could allow us to create drugs which have a specific target of a specific combination of genetic risks, rather than targeting everything.”
The research also found that clinical neuroticism - the tendency to be worried or fearful - could lead people to be depressed, however Dr Trzaskowski said those results highlighted the complexity of interpreting genetic information.
He said while the research showed a link from neuroticism to depression, there was no corresponding link from depression to neuroticism, meaning the genes involved were interacting in a more complex way than a straight back-and-forth.
Dr Grant Blashki, lead clinical adviser for mental health advocates Beyond Blue, said the study findings added significantly to what was already known about depression.
“The fact that depression illnesses tend to run in families is not a new finding, but this study adds weight to the importance of an area of the brain called the prefrontal regions in the development of depression and contributes to our knowledge of the biological mechanisms of depression,” Dr Blashki said.
“This more nuanced understanding of the genetic underpinnings of depressive disorders helps inform clinical, diagnostic and treatment decisions and, ultimately, may help doctors identify better medication for a particular individual.”
One in 16 Australians is believed to suffer from clinical depression, the equivalent of over 1 million people, according to figures from Beyond Blue.
Women are more likely than men to experience depression, at a rate of one in six women compared with one in eight men.
Worldwide, an estimated one in six people would develop the disorder during their lifetime.
The study used an innovative statistical method to identify sections of DNA common in people with depression.
The approach, known as Mendelian randomisation, allows scientists to look at
how a condition affects behaviour, while ruling out other influences such as age or
income.
