Researchers have found that a gene called NCAN is closely associated with the mood swings that occur in people with bipolar disorder.

People who suffer from bipolar disorder undergo radical mood swings - from being depressed to being highly excited.

"It has been known that the NCAN gene plays an essential part in bipolar disorder. But until now, the functional connection has not been clear," said Prof. Dr. Markus M. Nöthen, Director of the Institute of Human Genetics at the University of Bonn.

To study the effects of NCAN gene in bipolar disorder, researchers compared genetic factors and symptoms reported in over 1,200 bipolar disorder patients who were suffering from depressive or manic symptoms of the disorder.

The statistical analysis of gene along with symptoms showed that NCANN is closely linked with manic episodes in bipolar disorder. "Here it became obvious that the NCAN gene is very closely and quite specifically correlated with the manic symptoms," said Prof. Dr. Marcella Rietschel from the Central Institute of Mental Health in Mannheim.

However, researchers haven't found a link between the gene and depressive phase of the bipolar disorder.

In another part of the study, researchers knocked off the gene in some mice. Researchers found that these mice displayed more risk-taking behavior than the normal mice. These mice also exhibited more reward-seeking behavior. "It was shown that these animals had no depressive component in their behaviors, only manic ones," said Prof. Dr. Andreas Zimmer, Director of the Institute of Molecular Psychiatry at the University of Bonn.

The researchers then gave lithium to the mice that didn't have the NCAN gene. Lithium, first approved by FDA in 1970s, is used to treat people who suffer from bipolar disorder.

"The lithium dosage completely stopped the animals' hyperactive behavior," said Prof. Zimmer.

A genome wide association study had earlier shown that variation in NCAN had significant association with bipolar disorder. Another research has shown that genetic variation in the gene NCAN is a risk factor for schizophrenia and bipolar disorder.