Lithium, one of psychiatry's oldest drugs, may be the most effective solution for preventing suicide in patients with manic-depressive disorder and other types of bipolar disorders, according to a separate study. Nearly half of all US suicide deaths each year are in patients with bipolar disorders, for whom the risk is more than 20 times that of the general population, the researchers note.

$25,868 Billion-a-Year Price Tag

Approximately 4.3 percent of US adults suffer from a bipolar disorder or "sub-threshold" bipolar disorder -- which includes those who don't fit the precise clinical criteria for bipolar disorder but whose symptoms still severely impair their ability to perform daily tasks of living, according to the new prevalence figures. Previous studies placed the prevalence at just 1 percent.

The latest findings bring into sharper focus society's shared burden from bipolar disorder. They are part of a new analysis from the National Co-Morbidity Survey Replication (NCS-R), which is the first examination of societal costs associated with the illness. Dr. Ronald C. Kessler, Ph.D., professor of health care policy at Harvard Medical School and principal investigator of the NCS-R, presented the summary of the survey's preliminary results.

Compared to major depressive disorder, bipolar disorder has a significantly greater impact on an individual's ability to go to work or be productive when at work, according to the NCS-R, which included face-to-face interviews with 9,282 US adults.

On an annual basis, the mean number of lost days for someone with bipolar disorder is 49.5, versus 31.9 for someone with major depressive disorder. Nationally, bipolar disorder carries a $25,868 billion-a-year price tag, an economic burden not before appreciated, says Dr. Kessler, who believes previous research has over-estimated the societal costs of major depression while underestimating the costs of bipolar disorder.

Suicide Attempts More Often Lethal

Suicide -- quantifiable in terms of both the loss of human life and its impact on society -- is one of the significant costs associated with bipolar disorder. Of particular concern is the finding that bipolar patients are more successful at their attempts. They have about a one-in-five chance of being lethal, compared to a one-in-20 attempt-to-suicide rate within the general population.

The number of suicides and attempted suicides, as well as their associated costs, could be reduced significantly in the United States by a return to more widespread use of lithium, says Ross J. Baldessarini, M.D., another Harvard researcher. The use of lithium was more common before the introduction of newer drugs and continues to be standard practice in Europe. The first modern use of lithium to treat mania occurred more than 55 years ago.

Dr. Baldessarini, a professor of psychiatry at Harvard Medical School, and his team conducted a comprehensive, quantitative review of studies comparing rates of suicides and attempts among patients who were undergoing different treatments, receiving a placebo as part of a clinical trial, or receiving no treatment at all.

Lithium Reduces Suicides

Patients taking lithium had an 80- to 85-percent lower rate of attempts or completed suicides compared to patients with manic-depressive illness not being treated with lithium, with strikingly consistent findings across a large number of dissimilar studies, the researchers found.

"The effect that bipolar disorder has on individuals, their families, the work place -- society as a whole -- cannot be underestimated," comments Ellen Frank, Ph.D., professor of psychiatry at the University of Pittsburgh School of Medicine.

"While it's troubling that we are learning the burden is much greater than we even realized, we can take steps to reduce some of the hardship," Frank added. "One approach that may make sense, and which appears could help reduce the burden associated with suicide, is a lithium-based treatment."