Government researchers in the United States have found that the breast cancer drug tamoxifen helped treat the manic symptoms of bipolar disease.
The team of researchers from the National Institute of Mental Health (NIH) say even though tamoxifen may be too dangerous to be taken for bipolar disease, the findings may lead to better drugs to treat the mental illness.
Tamoxifen was tested because it blocks an enzyme called protein kinase C or PKC, which regulates activities in brain cells and PKC is thought to be over-active during the manic phase of bipolar disorder.
Bipolar disorder or manic depression affects an estimated 6 million American adults; sufferers experience profound mood swings ranging from very disabling depression to overwhelming excitement or extreme irritability.
Mania differs from the average mood swing where a person might feel very happy and can severely undermine people's jobs, relationships and health.
At times symptoms are severe enough to require hospitalization, and drugs that treat the manic symptoms take time to work and often have severe side effects; such drugs include lithium, antipsychotics and anti-seizure drugs.
NIMH Director Dr. Thomas Insel says people often believe the depressive phase of the brain disorder is the time of risk, but the manic phase has its own dangers.
The manic phase of bipolar disorder puts patients into an "overdrive" situation where they often indulge in harmful behaviours they might not otherwise engage in.
Risky pleasure-seeking behaviours with potentially serious health consequences are a feature, such as lavish spending sprees they can't afford and grandiose ideas regarding their own capabilities.