Genetics of depression could shed light on the illness

A new study identifying genetic risk factors associated with major depression provides new information about biological drivers that researchers say will help develop improved treatments in the long-term.
 
Published in the scientific journal Nature Genetics, the international research is said to be the biggest of its kind. It analysed DNA from more than 135,000 people with the disorder and more than 344,000 who did not have depression.
 
The research identified 44 genetic variants associated with major depression – 30 of which were previously unknown.
 
‘There is very, very strong evidence that there is a genetic factor, it’s just that we have never been able to work out from the DNA which genes are important, and this study is really pushing in that direction,’ Professor Naomi Wray from the University of Queensland’s Institute for Molecular Bioscience and Queensland Brain Institute, lead analysist of the data, told newsGP.
 
‘Environmental lifestyle factors contribute, but not everybody who experiences lifestyle risk factors ends up with depression … if you are genetically vulnerable then you are more likely to become affected.’
 
According to Professor Wray, major depressive disorder, symptoms of which include having a depressed mood for more than two weeks, is a ‘complex genetic trait’. She said it is commonly present in the population and affects one in six people at some point in life.
 
‘There are lots of hypotheses about depression, but if there were easy answers we would have found them,’ she said.
 
‘One of the things we know about depression is that it tends to run in the family … that rightly means there is some genetic contribution.’
 
Professor Wray said if researchers could identify DNA risk factors then they could get to the root of the disorder.
 
‘Because almost anything else you might measure in people with depression, you don’t know if it’s really a cause or a consequence,’ Professor Wray said. ‘Whereas when you work on genetics, it is trying to dig down to the roots.
 
‘It might be a long way around to get to an answer, but it might be the answer that is really going to open new doors.’
 
Study participants were recruited either through clinical research and directly interviewed by a psychiatrist, or had self-reported to an online testing company.
 
Professor Wray said the researchers’ ultimate goal is to help with ‘precision medicine’. They are conducting a further study to understand the factors that contribute to the differences in people’s responses to antidepressants.
 
‘We need to recruit more people into studies that analyse the genomes of depression sufferers,’ Professor Wray said.
 
‘A long-term goal could be that we can better stratify patients for antidepressant treatments based on their genetic profile.’

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