Closing in on a genetic map for depression

23 Jan 2019
Closing in on a genetic map for depression

An international team of researchers led by SAHMRI-based epidemiologist Dr Azmeraw Amare has opened the door to more rapid mapping of the genetic foundations of mental health disorders. 

The global collaboration, that included SAHMRI and the University of Adelaide, found eight never-before-identified gene variants related to increased risk of depressive disorder, and more importantly strengthened the evidence for genetic links between major depressive disorder (MDD), bipolar disorder and schizophrenia. The findings were published in Nature: Molecular Psychiatry

“Our success from including clinically overlapping psychiatric disorders in a single genome-wide association study (GWAS) has demonstrated that this might be the best approach to fast-track identification of the potentially thousands of genetic variations that raise a person’s risk of depression and related disorders,” Dr Amare said. 

Dr Amare’s team pooled GWAS summary data from five similar studies conducted in recent years, which between them identified 77 different gene regions linked to depression. The team found eight additional regions. 

Dr Amare says finalising a genetic map for psychiatric disorders is integral for the development of more accurate diagnoses and potential treatments. 

“It’s been well established from twin and family studies that genetics explains around 40 per cent of depressive disorders, however genes identified so far explain less than 5% of the heritability,” he said. 

“There are still hundreds, or potentially thousands, of genes involved in depression that we are yet to identify. 

“Once we have a clearer picture of which genetic regions are involved, we’ll be able to better define the different roles played by genes, other biological factors and their interaction with life experiences in the development of psychiatric disorders. That in turn will help clinicians to make a precise diagnosis and to provide personalised treatments.” 

Depression is a feeling of despondency that is persistent for an extended period. Symptoms can include changes in appetite and sleep patterns, loss of energy and motivation, impaired ability to concentrate and thoughts of self-harm or suicide. 

Bipolar disorder involves dramatic mood swings that can mirror depression symptoms at the “low” end, but also induces manic “highs” which can produce inflated self-esteem, decreased need for sleep, rapid and changing thought processes, increased goal-directed activity and excessive risk-taking behaviour. 

People with schizophrenia typically experience changes in behaviour and perception and disordered thinking. They might also suffer delusions or hallucinations where they hear voices or otherwise sense things that aren’t real. 

Depression, the most common of these disorders, affects around one million Australians each year, and around 300 million people worldwide. The World Health Organisation says depression is the leading cause of disability globally.