Older people often misuse prescription drugs because they fail to talk to their doctors and pharmacists, take several drugs at the same time and are unaware that a drug's effects may be magnified or reduced as a result of their aging, according to a study released yesterday.

"We call it 'the other drug problem,' " assistant federal health secretary Robert E. Windom said at a news conference called to announce a yearlong national campaign to focus public attention on unintentional and intentional misuse of drugs legally prescribed by health professionals for elderly people.

"For comparison's sake," Windom said, "we have about a million drug addicts in our country 'shooting,' 'snorting' or smoking illegal drugs. But we have close to 30 million older people taking legally prescribed medications, and half of them are simply not paying attention. That's got to be a cause for concern."

Windom said that people over 65 make up 12 percent of the population but consume 25 percent of all prescription medicine. With the number of older people increasing, elderly consumers are expected to account for half of all prescriptions dispensed by the year 2000, he said.

About 16,000 cases of adverse drug reactions involving elderly consumers were reported to the Food and Drug Administration during 1986, agency officials estimated. But the actual number probably was much higher, they said, because only a small fraction of the cases get reported.

The study of drug misuse problems among older Americans was prepared by the National Council on Patient Information and Education, a nonprofit group headed by former Florida representative Paul H. Rogers and financed by public and private organizations, including drug manufacturers.

Rogers said that the campaign -- labeled "Medicine: Before You Take it, Talk About It" -- will include brochures and posters explaining how drug misuse occurs and listing questions older consumers should ask their doctors, pharmacists and other health professionals about their prescription medicines.

The questions include: What is the name of the drug and what is it supposed to do? How and when do I take it and for how long? What foods, drinks, other medicines or activities should I avoid while taking this drug? Are there any side effects, and what do I do if they occur? Is there any written information available about the drug?

In addition, the council plans to seek public service messages on radio and television urging older consumers to ask their doctors and their pharmacists about prescription drugs.

Rogers said that the campaign, which is being implemented with a $203,000 grant from the Retirement Research Foundation of Park Ridge, Ill., also will call on physicians, pharmacists and other health professionals to take time to explain prescriptions clearly and thoroughly.

FACTORS IN ELDERS' DRUG MISUSE Poor communication between older patients and health care professionals (doctors, pharmacists and nurses).

Being required to take and manage a number of prescriptions at the same time.

Being treated by several health care professionals, all of whom may be prescribing medicines.

Insufficient awareness that a drug's effects can be magnified or reduced in older people because of aging processes in their bodies.

Failing to take medicine as prescribed -- due to vision, hearing and memory loss and other changes associated with aging.

Intentionally choosing not to take a drug or to stop taking it or otherwise to alter consumption. SOURCE: National Council on Patient Information and Education, October 1987.