If elderly people with dementia are so vulnerable to the risks posed by antipsychotics, why are so many nursing-home residents regularly prescribed the medications?

The answer can be found in a controversy with its roots in aggressive marketing and lackadaisical supervision. Known in the medical community as atypical antipsychotics, this group of drugs was originally approved by the Food and Drug Administration to treat adults suffering from schizophrenia. They go by snazzy names such as Zyprexa, Geodon, Abilify, and Seroquel. Later, regulators allowed doctors to prescribe them for treating bipolar disorder. Over the past decade, the pills have become a veritable goldmine; in 2008 alone, sales in the U.S. reached $14.6 billion.

But critics say those big sales are actually due, in part, to an epidemic of off-label marketing, which is promoting a drug for unapproved uses, although doctors are free to write a prescription regardless. And so drugmakers encouraged doctors to prescribe these meds for children before the FDA sanctioned their use for youngsters. This was particularly troubling, given that the drugs can cause diabetes and weight gain, side effects that prompted thousands of lawsuits claiming that drugmakers tried to hide evidence of these problems.

Another side effect is even more disturbing—unnecessary deaths among elderly patients, who shouldn’t receive these medicines if they suffer from dementia. A recent study found that more than 140,000 dementia patients in the U.K. are given these meds needlessly and some 1,800 elderly deaths are linked each year to overprescribing. Moreover, only 20 percent of 180,000 dementia patients received any benefit.

In general, people taking antipsychotics are nearly twice as likely to have a stroke compared with those not on the meds, according to a study in the British Medical Journal. And the risk is higher—about 3.5 times—for those with dementia, which means doctors should only prescribe the pills as a last resort.

Of course, there are people in nursing homes with behavioral problems such as agitation and psychotic episodes. Yet reports periodically emerge that chronically understaffed nursing homes all too often dispense antipsychotics in order to subdue patients. A recent investigation by the Chicago Tribune, for instance, found that nursing-home residents in Illinois are drugged without their consent or without a legitimate psychiatric diagnosis that would justify treatment.