Researchers say each of these disorders comes with its own set of symptoms, is caused by specific genetic abnormalities

Sep 16, 2014 07:02 GMT  ·  By
Study finds schizophrenia is not a single disease, rather 8 different disorders all rolled into one
   Study finds schizophrenia is not a single disease, rather 8 different disorders all rolled into one

Just yesterday, The American Journal of Psychiatry witnessed the publication of a paper that will forever change our understanding of schizophrenia. In a nutshell, this paper shows that schizophrenia is not a single disease, but 8 distinct disorders all rolled into one.

According to specialists at the Washington University School of Medicine in St. Louis, US, each of these eight disorders is caused by specific genetic abnormalities and consequently comes with its own set of symptoms.

Pinning down the genetic faults responsible for schizophrenia

Specialist C. Robert Cloninger and fellow researchers explain that, in order to pin down the faults that cause people to develop schizophrenia, they looked at the genomes, i.e. the genetic material encoded in DNA, of several thousand people.

More precisely, they analyzed the genetic makeup of as many as 4,200 schizophrenia patients and 3,800 healthy individuals who served as a control group. The end goal was to identify the genetic differences between these two groups.

Having split the schizophrenia patients into sub-groups based on symptom type and severity, the researchers found that this disease is caused not by a single genetic fault – not even a handful – but by a total of 42 genetic clusters that interact with each other and birth 8 distinct disorders.

These findings explain why it is that not all schizophrenia patients display the same set of symptoms. In fact, this disease has until now been linked to various types of hallucinations and delusions, no connection between thoughts and emotions, lack of initiative, and trouble organizing thoughts.

As detailed in The American Journal of Psychiatry, the more of the genetic faults underlying these 8 different disorders people have, the more likely they are to develop schizophrenia at an early age. Thus, a woman whose genetic profile gave her a 95% risk started hearing voices when just 5 years old.

One other patient, whose genetic makeup suggested that she had a schizophrenia risk of just 71%, took longer to display symptoms associated with this medical condition. Specifically, she started hearing voices in her adolescence, after turning 17.

“Most of the variability in the severity of disease has not been explained, but we were able to find that different sets of genetic variations were leading to distinct clinical syndromes,” specialist C. Robert Cloninger commented on these findings in an interview.

“What we’ve done here, after a decade of frustration in the field of psychiatric genetics, is identify the way genes interact with each other, how the ‘orchestra’ is either harmonious and leads to health, or disorganized in ways that lead to distinct classes of schizophrenia,” he added.

The importance of this research project

Having discovered that schizophrenia is not a single condition but rather an umbrella disease birthed by 8 distinct genetic disorders that may or may not manifest themselves all at the same time, the specialists behind this research project expect that this find will lead to improved diagnosis and treatment.

Given the fact that, as shown by previous investigations, about 80% of the risk for schizophrenia is inherited, knowing that this condition is brought about by 42 gene clusters that work together to trigger different symptoms is bound to make it easier to predict a person's chances to develop this disease.

“Genes don't operate by themselves. They function in concert much like an orchestra, and to understand how they're working, you have to know not just who the members of the orchestra are but how they interact,” C. Robert Cloninger, MD, PhD, wished to stress.

“In the past, scientists had been looking for associations between individual genes and schizophrenia. When one study would identify an association, no one else could replicate it. What was missing was the idea that these genes don't act independently. They work in concert to disrupt the brain's structure and function, and that results in the illness,” added specialist Dragan Svrakic, PhD, MD.