Psychologists have not understood schizophrenia very well. For the past decade or more, they have struggled to find effective ways to treat the disease. The disorder can be terrifying for those its afflicts, causing auditory hallucinations and a range of other symptoms.

However, a new research study shows that schizophrenia may be better classified as eight different disorders, each one genetically distinct and carrying different symptoms. This could be a huge breakthrough in diagnosing and treating schizophrenia.

The new research study was done at Washington University School of Medicine in St. Louis. The research was published today, September 15, in the journal American Journal of Psychiatry.

The research team began the new study hoping to find a genetic link to schizophrenia. Scientists know that 80% of people with schizophrenia inherit it genetically, but they have so far been unable to find the exact genes that trigger schizophrenia. This new study of 4,200 individuals with schizophrenia found not just one, but eight different types of gene combinations that are linked to the disease.

"Genes don't operate by themselves," said C. Robert Cloninger, MD, PhD, one of the senior researchers on the study. "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."

The researchers found one set of genes that were associated with hallucinations or delusions. They found that 95% of people with this gene had schizophrenia. They found another set of genes associated with disorganized speech or behavior and saw that those genes indicated a 100% risk of schizophrenia.

Cloninger said that the team had untangled the ways genes worked together to cause subsets of schizophrenia.

Individual genes are not enough to determine schizophrenia risk, the study shows. The eight gene clusters the study identified indicated a 70-100% chance of schizophrenia, an extremely high correlation.

The team found these genetic clusters by separating patients by symptom type, and then looking at the genetic variation within those groups.

The team successfully reproduced their results in two different DNA databases of schizophrenics, indicating that there is very strong evidence that the gene clusters they found are truly linked to schizophrenia.

Igor Zwir, PhD, one of the researchers on the project, said that it might be possible soon to individually target a new form of treatment to each of the eight types of schizophrenia the team found.