A study of bipolar disorder (BD) shows a genetic link to schizophrenia and major depression but also identifies some potential therapy targets.
A team of international and Australian researchers, led by Niamh Mullins of the Icahn School of Medicine at Mount Sinai, US, identified 64 genetic locations that were associated with BD. Almost half of these locations have previously been linked to schizophrenia and seven locations were linked to major depression.
As described in a paper published in Nature Genetics, the team conducted a Genome Wide Association Study (GWAS) of 42,000 people with BD. This technique scans the genome of a large group of people to find common genetic markers that predict the presence of a disease.
Underlying genetics can give an indication of whether somebody is at risk of developing BD, but there are also other lifestyle factors than can contribute.
“The study also suggested a role of sleep habits, alcohol, and substance usage in the development of bipolar disorder, although further research is needed to confirm these findings,” says Mullins.
With this data, they also found that different types of BP had slightly different underlying genetics.
“Specifically, bipolar I disorder shows a strong genetic similarity with schizophrenia, whereas bipolar II disorder is more genetically similar to major depression,” says Mullins.
They found that many of the genetic locations were genes that work in the brain and synaptic signalling. Particularly, some of the genes were involved in calcium channels, which are small biological tunnels that let electrical signals into neurons.
“The finding that many DNA variations that increase risk of bipolar disorder are involved in calcium signalling, suggests that drugs such as calcium channel blockers (already used for the treatment of high blood pressure and other conditions of the circulatory system), could be investigated as potential treatments for bipolar disorder,” says Mullins. “However, we emphasize that future research to directly assess whether these medications are effective in the treatment of bipolar disorder is essential.”