Depression is currently the leading cause of disability worldwide according to the World Health Organization, and recently researchers have found 78 genes that could further explain this condition.
Scientists at the University of Edinburgh analyzed patient data from UK Biobank, an international resource dedicated to the study cancer, diabetes, stroke, cardiovascular diseases, and other life-threatening conditions.
DNA records of 322,580 individuals were scanned to identify if certain genes can be linked to three major depression phenotypes: broad depression, major depressive disorder, and ICD-9 and ICD-10-related MDD. Broad depression is characterized as having "nerves, anxiety, tension, and depression."
They thought that the genes responsible for triggering depressive symptoms are related to synapses, the cell connectors which transmit electrical and chemical signals.
To test their hypothesis, the scientists conducted a parallel study of genetics data from 23andMe, a genomics and biotechnology company based in Mountain View, California.
"Depression is a common and often severe condition that affects millions of people worldwide. These new findings help us better understand the causes of depression and show how the UK Biobank study and big data research has helped advance mental health research," said Dr. Andrew McIntosh, a professor at the University of Edinburgh Center for Clinical Brain Sciences.
Of the identified genes in the study, 78 were associated with broad depression, two genes with probable MDD, and one gene with ICD-coded MDD. The researchers wrote that broad depression may include types of personality or psychiatric disorders, while MDD and ICD-coded MDD "offer more robust definitions for depression."
Lead author Dr. David Howard said their findings present a whole new perspective in understanding depression, adding that the research suggests the disease is "partly genetic."
The study was published April 16 in Nature Communications.
In 2017, 23andMe recruited 15,000 individuals with depression and 10,000 people with bipolar disorder for genetic data pooling. The research is meant to understand the role of genes in specific neurological processes like decision-making, visual perception, and attention.
"By studying intermediate phenotypes such as cognitive function alongside genetics and other environmental variables on a massive scale, we hope to take a significant step forward in the study of depression and bipolar," said Dr. Emily Drabant Conley, VP of Business Development at 23andMe.
Similarly, a 2016 study published in Nature Genetics, in conjunction with Massachusetts General Hospital and Pfizer, pinpointed 15 genetic locations that are associated with major depression.
The study data came from 23andMe consenting clients of European descent, who were grouped based on self-reported history of depression.