Approximately 500,000 Spaniards and 21 million people around the world suffer from schizophrenia , a mental illness that, according to a report that has just been published in the Canadian Medical Association Journal, triples the risk of mortality among those affected. On average, schizophrenics usually die eight years earlier than people without this ailment, since they would be more exposed to unhealthy habits such as smoking and sedentary lifestyle, as well as the side effects of the medication they take.
It is estimated that in our country the costs associated with schizophrenia amount to 8,000 million euros, and it is the third leading cause of disability among the young population . It is, therefore, a serious public health problem in which it is a priority to find out its causes and determine the best ways to prevent and treat it.
The latest news comes from the University of Copenhagen, in Denmark, whose researchers have announced the conclusions of the largest study on this psychiatric disorder carried out with twins. And their data confirm the importance of the heredity factor: 79% of the risk of contracting it would be explained exclusively by genetic reasons . The work, echoed by the journal Biological Psychiatry, attempted to refine the results of previous statistical studies, based on whether individuals suffered from schizophrenia at that time or not, without assessing the risk of contracting it later.
Hunting for the gene
Dr. John Krystal, director of Biological Psychiatry , has put into context the figure estimated by Danish specialists: “ this 79% is at the upper end of the percentages proposed so far , which ranged between 50% and 80%, which supports the intense scientific efforts to locate the genes responsible for schizophrenia ”.
The experts from the University of Copenhagen have taken advantage of the exhaustive database of the Danish Twin Register, in which all twins born in Denmark from 1870 onwards are registered, information collated with that of the Danish Psychiatric Central Research Register. In the end, the researchers have been able to examine the cases of more than 30,000 pairs of twin brothers .
In addition, research has taken into account other disorders that are not strictly schizophrenia, but belong to the same spectrum of psychiatric disorders. And in this case, the heritability rate is also very high: it amounts to 73% .
“Our study is the most complete and rigorous estimate of the genetic component of schizophrenia and its diagnostic diversity,” says Hilker Rikke, one of the authors of the report. Because, as this specialist also points out, the weight of the congenital factor is revealed practically the same in all manifestations of the disease , which can produce from mild symptoms to completely incapacitate the affected person.
One of the latest advances in this regard is the discovery of a rare genetic variant, called RTN4R, which may play a decisive role in the development of schizophrenia, as suggested by Japanese researchers in the journal Translational Psychiatry . This DNA fragment is associated with the production of myelin , a substance that acts as a conductor of electrical signals between neurons, and whose abundance or absence is directly related to the correct functioning of the brain.
