Genetic link to depression discovered?
by Thomas Kabir
A consortium of researchers from Oxford and China has discovered two specific regions of DNA that have been linked to depression. These findings were published in Nature in July this year. The results are some of the strongest evidence yet that genetics do indeed have some part to play in depression.
There has been research before that have made similar claims. The problem is that the research was typically based on a relatively small number of people making the findings somewhat unreliable. So what makes this research different? Firstly, the research published in Nature is based on quite a large number of people (5,303 Chinese women with severe recurrent depression, and 5,337 healthy ‘controls’). And secondly, an independent group of thousands of people with depression from north of China had the same two genetic ‘markers’ that were found in the main study sample of 5,303 women with depression. In other words the findings seem to hold even when you look at a completely independent group of people. The caveat being all these populations samples are from one country – China.
What is also intriguing is where these two ‘markers’ are. One of the markers is next to a gene that carries some of the instructions for making the mitochondria. Mitochondria are the ‘batteries’ of the cell. They produce the raw energy that powers the cell. As an aside, when things go wrong with mitochondria very bad things can happen. Indeed, a new treatment called mitochondrial IVF was recently approved to help prevent what is generally called mitochondrial disease. The implication is that depression just ‘might’ have some kind of relationship to the ways that mitochondria work. There are some hints that this might be the case. But for the time being this is pure speculation and it would be wrong to firmly link depression with mitochondrial disease at this stage.
As with much genetic research there appear to have been little actual involvement of people with lived experience of mental illness in this study. Why is this important? Because people with depression can help interpret findings and ask questions to help improve the design and conduct of studies. Whilst the research does appear to be robust, and therefore the findings reliable, it also raises several questions. The research involves a sample of mostly severally depressed women in China. What would have happened if the sample were taken from Finland? What would have happened if the sample was made up of men with mild depression? Is there something about the way that depression is understood and managed in China that might have had some impact on the findings of the research?
Of course, all these issues would have been considered at some point by the researchers behind this study. But it does seem likely that some involvement of people with depression would have helped the wider research team. There is a wider issue of what you do with the results. How would you communicate the findings of this study to someone with depression? Would not a danger be that people blame their depression on their ‘genes’? Or that people might be discriminated against based on the results of genetic tests? This all needs to be thought through. People with lived experience are (in my view) ideally placed to help here. There is a more general moral argument that it’s right to involve people who are most likely to be affected by the research in the way that it is carried out and used.
There have been calls for more large scale research into the genetics of depression. Looking outside of mental health there is a lot of genetic research going on in the UK. Indeed a publically funded project is currently underway to sequence the genomes of 70,000 people. With more research there are bound to be more discoveries. This is good. But patient and public involvement needs to keep pace and it needs to be properly resourced. My worry is that for a variety of reasons it isn’t.
So where does the research leave us? Well for me the discovery of the two genetic ‘markers’ take us two small steps closer to understanding depression. This can only be good news. I can’t help but feel that the active involvement of people with lived experience of mental illness will help us take even more of these steps even quicker.
Dr Thomas Kabir
McPin Public Involvement in Research Manager
If you would like to read the original research paper you can do so by clicking here. The paper is understandably quite technical.
A very informative special feature on depression appeared in Nature late last year.