Breast cancer drug tamoxifen helps treat symptoms of bipolar disease

Sep 13 2007

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.

Dr. Insel says being able to treat the manic phase more quickly would be a great asset to patients, not just for restoring balance in mood, but also because it could help stop harmful behaviors before they start or get out of control.

The researchers led by Dr. Husseini Manji tested 16 patients experiencing manic episodes, who got either tamoxifen or a placebo for three weeks; they found that 63 percent of the patients taking tamoxifen had reduced manic symptoms, compared with only 13 percent of those taking a placebo.

Neither the patients nor the researchers knew which of the substances the patients were getting.

What is more the tamoxifen benefits appeared within five days.

Tamoxifen blocks some of the effects of the hormone estrogen but can raise the risk of endometrial cancer in women.

Dr. Manji says there is now proof in the principle that targeting PKC directly, rather than through the trickle-down mechanisms of current medications, is a feasible strategy for developing faster-acting medications for mania.

The research is published in the journal Bipolar Disorders.