Campus & Community

Lithium drugs found to reduce suicide risk

4 min read


Lithium drugs may reduce the risk of suicide among people with severe recurrent depression by as much as 82 percent, according to a new Harvard study. That finding may help millions of people who struggle with potentially lethal mood disorders.

The researchers, working at Harvard-affiliated McLean Hospital in Belmont, analyzed 22 studies involving 5,647 patients. Those who took the drug showed a nine-fold lower rate of suicide compared to those who did not.

“The evidence we have provides strong, consistent support that suicides are dramatically lower with than without long-term lithium treatment,” says Ross Baldessarini, a professor of psychiatry who participated in the study. He estimates that 10 million people in the United States with major mood disorders could be affected by these results.

At present, the drugs most commonly prescribed for depression are so-called selective serotonin reuptake inhibitors, such as Celexa, Paxil, Prozac, and Zoloft. These medications are safer than lithium-containing drugs, which include Lithobid, Eskalith, and several generic products. However, in another study Baldessarini and his colleagues found no evidence that serotonin drugs and other antidepressants reduce risk of suicide.

“Instead, the recent shift to safer antidepressants may be associated with a move towards more lethal means of self destruction,” Baldessarini asserts. “You can’t overdose as easily with serotonin drugs, so people bent on suicide choose guns, cars, or jump from windows.”

Striking results

Baldessarini and colleagues Leonardo Tondo and John Hennen reported their results in recent issues of the international medical journal Acta Pyschiatrica Scandinavica and in the Annals of the New York Academy of Sciences. They write that “despite the grave personal, social, and economic impact of suicide and its strong association with depressive disorders, specific studies on the effects of mood-altering treatments on suicide risk remain uncommon.”

Suicide risk in people with mood disorders is 10 to 20 times higher than that in the general population, and as many as 25 percent of severely depressed or manic-depressive patients take their own lives. In a search for ways to reduce this toll, the Harvard researchers analyzed 22 studies conducted between 1970 and 1998. They compared suicide rates among patients who took lithium for several months to more than a year with those who did not take the drug.

“The results were clear and striking, particularly among bipolar manic-depressive patients,” Baldessarini comments. They reinforced the Harvard group’s other finding that suicides and suicide attempts increased 20 times in manic-depressives within the first year after abruptly discontinuing lithium treatment. After the first year off lithium, rates of suicidal behavior were virtually identical to those before patients started the treatment.

Serotonin is a natural chemical involved in transmission of information between brain cells. Evidence suggests that people who are suicidal have lower than normal levels of it. Prozac-type drugs act by raising serotonin levels. Lithium could also act in this way, but it’s not known if it does. “Lithium is a common element that enters every cell in the body so its actions are incredibly complex,” Baldessarini admits.

The Harvard researchers are now looking at the long-term effects of serotonin medications such as Prozac and other types of antidepressants on suicide rates. “Pharmaceutical companies have done short-term rests (usually about six weeks) on serotonin drugs, and these do not show any reduction in suicide rates,” Baldessarini notes. Long-term studies might show a cheerier outcome.

An 82 percent, or nine-fold reduction, in suicide risk is impressive. Even a much lesser reduction in the likelihood of death from, say, a cancer drug would be phenomenal. But Baldessarini remains cautious. “Patients in this study were motivated enough to cooperate with long-term treatment, and the attention they received may have made them feel less vulnerable,” he says. In other words, they may have been less likely to commit suicide in the first place.

Yet despite the popularity of newer drugs, Baldessarini maintains that, “our analysis shows that lithium is a good option to choose for long-term treatment of severe depression, particularly depression associated with bipolar manic-depression.”