In recent years, the newer drugs, which account for about 90 percent of the market, have become increasingly controversial, as prescription rates to children and elderly people have soared. Doctors use the drugs to settle outbursts related to a host of psychiatric disorders, including attention deficit disorder and Alzheimer’s disease. Most are not approved for such use. After an analysis of study data, the Food and Drug Administration required that all antipsychotics’ labels contain a warning that the drugs were associated with a heightened risk of heart failure in elderly patients.

The new study, an analysis of more than 250,000 Medicaid records, is the first to rigorously document that risk for the newer drugs in adults over 30 without previous heart problems.

In the study, researchers at Vanderbilt University and the Nashville Veterans Affairs Medical Center analyzed Tennessee Medicaid records for 276,907 people ages 30 to 74. About a third of them began taking an antipsychotic medication in the period studied, from 1990 to 2005, either a newer atypical or an older drug. Two-thirds made up a control group. The researchers excluded patients with heart disease or other problems that might put them at higher risk of cardiac failure. Antipsychotic drugs can affect heart rhythm in some vulnerable people.

They found 478 sudden cardiac deaths among those taking the drugs, about twice the rate of the control group. The risk  equivalent to 3 deaths for every 1,000 patients taking the drugs for a year  was about the same whether people took the newer or older medications. The higher the dose of the drug, the study found, the higher the risk of sudden death.

“The implication of this study is that physicians need to do a very careful cardiovascular evaluation prior to prescribing these drugs,” especially if there are alternative treatments, said the lead author, Wayne A. Ray, a professor of preventive medicine at Vanderbilt and the Nashville veterans’ hospital. “Then, if they’re used, to pay careful attention to using the lowest possible dose.”