• Depression affects more than 350 million people worldwide. (Getty Images)Source: Getty Images
Depression affects more than 350 million people worldwide, and this study provides a clue for why that's the case.
Shami Sivasubramanian

4 Aug 2016 - 11:53 AM  UPDATED 4 Aug 2016 - 11:54 AM

In the largest study of its kind, genetic research firm 23andMe along with drug manufacturer Pfizer and Massachusetts General Hospital have combed through genetic data from over 300,000 people, revealing several potentially genetic indicators of depression in individuals of European descent.

“[The study] identified 17 single nucleotide polymorphisms in 15 genetic loci significantly associated with depression among people of European ancestry,” reads 23andMe’s statement on their blog.

Scientists have long suspected that genetics play a part in depression, however many of the studies in this area fail to deliver conclusive results - often due to lack of available data.

“One study in 2013 by the Psychiatric Genomics Consortium (PGC) looked at data from more than 17,000 people with depression, but couldn’t detect any genetic hits," reads the official blog post. 

“Jonathan Flint, a geneticist at the University of Oxford and a key researcher in the PGC study, concluded that he either needed more data from more individuals to find a signal, or a more select group of individuals to study, according to an article in the journal Nature."

Dr Flint later conducted another study with 10,000 individuals from China, “a cohort that was relatively homogenous and had the most severe depression”, where he discovered two genetic indicators of with depression, uniquely in people of Han Chinese descent.

“We hope these findings help people understand that depression is a brain disease with its own biology”

Taking this lesson of data and sampling into account, this genome-wide association study published in Nature Genetics is the largest of its kind, using data from over 450,000 customers who “consented to research and completed online surveys about depression”. From this data trove, 75,607 self-reported having depression and 231,747 were healthy controls. The subjects were all of European descent. 

This ‘crowd-sourcing’ of medical data from everyday people has naturally raised concerns as to the data’s accuracy, because self-reported depression can mean the illness could have been over-represented in the sample, with people reporting it even though they have no official diagnosis.

Nonetheless, due to the sheer size of the study, the researchers from 23andMe are hopeful that the findings could contribute “to better understanding of the biology of the condition” of depression and other mood disorders. 

“We hope these findings help people understand that depression is a brain disease with its own biology,” Roy Perlis, associate director of the psychiatric genetics program in mood and anxiety disorders at Massachusetts General Hospital, told The Washington Post.

“Now comes the hard work of using these new insights to try to develop better treatments.” 

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