Bipolar Patients with Schizophrenia Genes May Not Respond to Lithium

Patients with bipolar disorder who do not respond to lithium treatment all share something in common: a high number of genes previously identified for schizophrenia, according to a new international study led by the University of Adelaide in Australia.

Lithium, widely considered the “gold standard” treatment for bipolar disorder, has been commonly prescribed since the 1950s because of its mood stabilizing effect. It has been shown to protect against both manic and depressive episodes and to decrease the risk of suicide.

However, about 30 percent of bipolar patients are only partially responsive. In fact, more than a quarter show no clinical response at all, and others have significant side-effects to lithium.

Until now, researchers have not understood why these patients do not respond to the common treatment, while others respond well to the drug.

The research involved an international group of scientists led by the University of Adelaide’s Professor Bernhard Baune who has been studying the underlying genetics of more than 2,500 patients treated with lithium for bipolar disorder.

“We found that patients clinically diagnosed with bipolar disorder who showed a poor response to lithium treatment all shared something in common: a high number of genes previously identified for schizophrenia,” said Baune, head of the Discipline of Psychiatry at the University of Adelaide and lead author on the paper.

“This doesn’t mean that the patient also had schizophrenia, but if a bipolar patient has a high ‘gene load’ of schizophrenia risk genes, our research shows they are less likely to respond to mood stabilizers such as lithium.

“In addition, we identified new genes within the immune system that may play an important biological role in the underlying pathways of lithium and its effect on treatment response,” says Baune.

Investigating the underlying biology of people’s response to lithium treatment is a key area of research and an urgent clinical need in mental health.

“These findings represent a significant step forward for the field of translational psychiatry,” Baune said. “In conjunction with other biomarkers and clinical variables, our findings will help to advance the highly needed ability to predict the response to treatment prior to an intervention. This research also provides new clues as to how patients with bipolar disorder and other psychiatric disorders should be treated in the future.”

Their findings are published in the journal JAMA Psychiatry.

Source: University of Adelaide