Globally, at least one in eight people lives with a mental illness, and depression is one of the leading causes of disability, according to the World Health Organization (WHO).
The WHO also estimates that the number of people with anxiety and depression increased by up to 25 percent in the first corona year.
Therefore, there is a great need to understand and treat these common, serious conditions.
Now researchers from the University of Oslo, among others, are wondering whether it is true that we see schizophrenia and bipolar disorder as different disorders, for example, since the genetic overlap is very large.
Supercomputer calculates millions of variants
The research, published in The American Journal of Psychiatry, looked at genetic data from more than 200,000 people with a mental disorder.
Initially, the genetic overlap between bipolar disorder, ADHD, depression and schizophrenia was examined. A team of 30 math, statistics and computer science experts used advanced math to analyze millions of genetic variations.
Using a supercomputer, which is thousands of times more powerful than ordinary computers, the researchers studied genetic variants associated with bipolar disorder and compared them with variants associated with schizophrenia.
Another look
They discovered 10,000 genetic variants associated with mental disorders, many of which are common to multiple disorders.
One of the findings was that bipolar disorder and schizophrenia have an overlap of 8500 genetic variants, while ADHD and depression have an overlap of 4500 genetic variants.
The risk of depression is influenced by 14,500 gene variants, of which 7,500 can also influence the risk of bipolar disorder. Lead author Guy Hindley explains:
‘The findings may represent an important shift in our view of the genetic basis of mental disorders. Our research shows that probably thousands of genetic variants play a role in the risk of schizophrenia, rather than a small number of genes specifically influencing that risk,’ he says.
May prevent side effects
It’s not the first study to show that many mental disorders have similar genetic causes. Samples have previously been collected from more than 100,000 people, and a number of gene variants have been found that can increase the risk of a mental disorder.
But this is one of the first studies to provide a rough estimate of the number of genetic similarities between different mental disorders.
Hindley hopes that thanks to this discovery we will be able to better define the disorders in the future, limit the number of causes and thus tailor a treatment so that the large group of people with depression, for example, does not just end up in the same box.
“The reason we still have the current system, with psychiatric diagnoses, is that there are no better alternatives. But I hope that with these more biological measures we can classify patients into groups that are more similar. For example, we can also prevent people who do not benefit from medication from having to live with side effects,’ he says.