Study: Genetic link between bipolar disorder and schizophrenia

by Jacob Fuller

Lauren Dempsey, MS in Biomedicine and Law, RN, FISM News 


A new study has shown that bipolar disorder and schizophrenia may be even more closely related than previously known.

Led by scientists at the Stanley Center for Psychiatric Research at the Broad Institute of MIT and Harvard, the study found that there may be similar genetic factors linking bipolar disorder (BD) and schizophrenia. The two conditions also have overlapping signs and symptoms, making diagnosis difficult. The results of the study were published in April in the Nature Genetics journal.

Researchers were able to identify a gene called AKAP11 as a strong risk factor for BD and schizophrenia after evaluating thousands of individuals with BD. This is the first gene discovered that may have a big impact on understanding risk factors associated with the conditions and may lead to a better understanding of how to treat patients.

The team of researchers compared the genomes of about 14,000 people with BD to 14,000 healthy controls. People with BD were more likely to carry certain gene variants that resulted in dysfunctional proteins, some of which have been previously associated with an increased risk for schizophrenia.

They then looked at results from the Schizophrenia Exome Sequencing Meta-analysis (SCHEMA) consortium, a long-term study, and combined the genome sequences of 24,000 people with schizophrenia who participated in the study with those of the 14,000 people with BD, comparing the genome sequence in those with the conditions to that of healthy controls.

Dr. Steven Hyman, director of the Stanley Center for Psychiatric Research at Broad Institute of MIT and Harvard spoke about the research.

“This work is exciting because it’s the first time we’ve had a gene with large-effect mutations for bipolar disorder,” he said. “This is an important step towards the kind of research into disease mechanisms that, across the history of medicine, has underwritten successful therapeutics.”

The main treatment for bipolar disorder is lithium, a mood stabilizer, but the drug doesn’t help all patients and can have significant side effects such as nausea, diarrhea, incontinence, hallucinations, seizures, confusion, and can cause fluctuations in blood pressure and irregular heart rhythms. Researchers at the Broad Institute are hopeful that this study will help to understand both how BD and schizophrenia occur, and how lithium improves symptoms when it does work.

These results have already prompted the start of new research at the Broad Institute to further evaluate these conditions in cells and animals, focusing on the mechanisms at a molecular level that will hopefully help to identify biomarkers that could help develop new drugs or use currently available drugs to better treat patients. The researchers are also exploring whether AKAP-11 could be used as a biomarker for BD or schizophrenia to help with the diagnosis process and to be used in future clinical trials that would include patients who are most likely to benefit from a particular therapy.

Benjamin Neale, director of genetics for the Stanley Center and co-director of the Program in Medical and Population Genetics at the Broad Institute explained that “The AKAP11 variants don’t contribute much to risk among the population as a whole, but the real value is what they reveal about the roots of disease, and that’s why we’re really focused on them.”