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A global study has uncovered almost 300 previously unknown variations of genes that are linked to depression, which researchers hope could improve diagnosis and treatment for more people.
Australians were among the researchers who analysed data from 29 countries, in what’s said to be the world’s most diverse genetic study into the complex mental health condition.
The research, published in the journal Cell, was publicly released on Wednesday.
Depression, also known as depressive disorder, is characterised by a low mood or loss of pleasure or interest in activities for long periods of time, and can affect all aspects of a person’s life.
An estimated 22 per cent (around one in five) Australians aged 16 to 85 experienced a mental illness across a 12-month period, according to the Australian Institute of Health and Welfare, citing 2020-22 data.
The data estimated that 43 per cent of Australians aged 16 to 85 (8.5 million, around two in five) had experienced a mental illness at some time in their life.
Source: SBS News
One in seven Australians will experience depression, according to mental health research and support organisations the Black Dog Institute and Beyond Blue.
While several factors can contribute to the risk of developing depression, experts say it has a biological component.
“We know that depression is a highly complicated disorder, and we’ve known for a while that there is a biological basis,” Dr Brittany Mitchell from the QIMR Berghofer Medical Research Institute told SBS News.
“But really, what this is and how many genes are playing a role in depression has still been an area that has been mostly unknown.”
The team of researchers, led by the University of Edinburgh and King’s College in London, started analysing data from 29 countries in 2017.
This included genetic samples from 680,000 people with depression and four million people who had not experienced it.
One in four participants were from a non-European background.
A ‘major limitation’ of genetic research
Broadly speaking, Mitchell said genetic research has primarily involved people of European ancestry, which is a “major limitation”.
“Our motivation, ultimately, is to provide better treatment options for people suffering from depression,” she said.
“So it was really important for us to make sure that our sample was as representative as possible, and to include as many people from different ancestries around the world.”
The researchers identified a total of 697 variations of genes that can make someone more susceptible to having depression, of which 293 had not been associated with the condition before.
“We know that depression is very different from person to person, and can also look different between people from different cultures,” Mitchell said.
“By looking across such a wide range of people, we were able to identify a comprehensive overview of the genetic basis of depression.”
The research acknowledges each genetic variant has a very small effect on the overall risk of someone developing depression. However, if a person has multiple variants, this can cumulatively increase their risk.
Predicting risk, improving treatment and ‘tackling’ stigma
Mitchell said researchers were excited about the “magnitude” of genes that were discovered — including very specific cell types within the brain and biological pathways that appear to be associated with the condition.
She said the findings could help to, firstly, use a person’s genetic profile to predict their risk of developing depression, and, secondly, to widen treatment options.
“By understanding the biology, and exactly what processes are going on in the brain, this allows us to find new treatments that target these processes better and provide more tailored treatment.”
Dr Luke Martin, a clinical spokesperson for Beyond Blue, said such studies help us to understand more about the complexities of a condition like depression.
“This is an impressive global study. By identifying so many new genetic variants, this research adds to our understanding of the biological basis of depression and opens up new avenues for prevention and treatment,” he said.
Martin said the diverse set of participants “gives us confidence that the findings can be applied to a really wide range of people”.
Mitchell agreed the findings would be applicable for more people across the broader population — and could help to reduce societal stigma about the condition, which can impact diverse groups.
“There are a lot of cultural factors when it comes to mental health and the ability to seek help or speak openly about it,” she said.
“This might also help to tackle that.”
‘The causes of depression are complex’
Martin said that while depression has a genetic basis of around 40 to 50 per cent, “the causes of depression are complex, and your genes don’t determine everything”.
“Depression typically results from a mix of your genes as well as environmental and situational stressors,” he said.
Mitchell also acknowledged depression is a complicated disorder, and that there can be many causes.
“By no means are we saying that genetics is the only cause of depression,” she said, adding things like environment and lifestyle “also play a very important role”.
“What we would like to reinforce is that for some people, depression will have a biological basis and that that’s also important to acknowledge.”
Readers seeking support with mental health can contact Beyond Blue on 1300 22 4636. More information is available at .
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