‘Monumental’ study identifies genetic link to depression

A new study has found significant associations between certain genes and depression – the first time such an association has been reported in individuals of European descent.

"We've seen previous findings from this type of approach in an Asian population, but not in a European one," said Ashley Winslow, a geneticist with the University of Pennsylvania and pharmaceutical giant Pfizer.

Depression is a serious illness that can affect people of any age. According to the Irish volunteer group Aware, which helps depression sufferers, more than 450,000 people in Ireland – 1 in 10 of the population – are affected.

People are more likely to suffer from depression if they have a family history of the disease. This has been known for some time, but the genes responsible for this effect have never before been identified.

Genetic predisposition

Dr Winslow called the results of the study “monumental”.

"I would hope this brings an application for depression patients," she said. "The whole aim of generating the data is understanding the genetic predisposition for depression.

“[If] we can understand the biology of the dysfunction that takes place, then we can develop therapeutics for treating the disease,” she added.

The results were published yesterday in the scientific journal Nature Genetics.

The researchers compared whole genomes of individuals who had either reported a previous clinical diagnosis of depression or were currently under treatment for it, with those of individuals with no history of depressive disorders.

The analysis revealed the existence of 15 regions in the genome that were altered in individuals reporting depression.

Known genes

The alterations were found in genes known to participate in the normal functioning of the nervous system or in its development. Some of these genes had previously been associated with other psychiatric disorders, such as schizophrenia, but never with depression.

The study obtained the samples from customers of the genomic company 23andMe.

Previous studies of this nature used samples from patients with a clinical confirmation of diagnosis, but in this case the individuals self-reported their links with depression, said Dr Winslow.

This allowed them to collected a lot more samples. But too ensure that the results were valid, they only analysed samples from individuals reporting having been diagnosed with depression or being under treatment for it.

For further confirmation, the results were tested in other clinically collected samples, with similar results.

Vanesa Martinez is on placement at The Irish Times under the BSA/SFI media fellowship programme