Twenty-five years ago, when I began my career as a physician-scientist and clinical psychiatrist, I was both intrigued and humbled by my work with patients suffering manic-depressive illness. Intrigued by a disorder that had typified "insanity" through the ages, I was humbled by my virtual helplessness, as a doctor, in the face of the relentless recurrence of episodes.

While I was a student, studies were under way to examine an observation, initially made in the course of unrelated animal research, that a naturally occurring salt compound appeared to curb hyperexcitability, a trait characteristic of mania, without causing oppressive sedation. My own research on this substance -- lithium -- helped confirm its effectiveness in dampening the recurrence of destructive highs and crippling depression that characterize manic-depressive illness.

Approved by the FDA in 1969, lithium has yielded savings of more than $12 billion in treatment over the past two decades. More important, it and other medications have improved the quality and saved the lives of countless patients.

The account of lithium is not unusual in the annals of modern medicine. In recent years, biomedical science has made obsolete many once dreaded illnesses. Today, polio is history; 80 percent of infants born with congenital heart defects are treated surgically and lead normal lives; the survival rates for many cancers are being steadily extended. The list of accomplishments is long, and we assume that progress will continue.

Indeed, research must continue because today we face an array of complex public health problems. These range from drug addiction to the spiraling frequency of Alzheimer's disease linked to the aging of our population, as well as AIDS, multiple sclerosis, cancer and mental disorders such as schizophrenia. Yet, to an extent unimaginable only a decade ago, biomedical science is under spirited attack; the continuity of medical advances is at risk, and the future quality of health care is in question.

The attack comes under the banner of "animal rights." At the movement's core is a vocal fringe who believe animals possess moral and legal rights absolutely identical to those of humans and who consider any use of animals by people immoral. "Species-ism," they say, is as reprehensible as racism.

Driven by this philosophy, animal rights activists want to prohibit the use of animals in basic biological and medical research. As Ingrid Newkirk of People for the Ethical Treatment of Animals asserts, "Animal research is immoral even if it's essential." A similar position is echoed by the president of Last Chance for Animals: "A life is a life. If the death of one rat cured all diseases it wouldn't make {it right} . . . we're all equal."

To the vast majority of Americans -- who, by the way, generally assign high priority to the humane treatment of animals -- the radical position of animal "rights" is unacceptable. Knowing this, rather than acknowledge their agenda openly, the activists use various ploys to recruit support.

A common tactic is to depict research with animals as inherently cruel. This purposeful misrepresentation ignores what should be obvious -- that necessary anesthesia is routine and that undue distress on the part of an animal subject can invalidate a study's findings. Great care is taken -- indeed is required by law -- to assure an animal's well-being. Yet the lie persists.

Another false assertion by activists is that animals are not needed in modern biomedical science. They claim that adequate "alternatives" to animal studies exist in the form of tissue cultures and computer models of illness and proposed treatments. In fact, these techniques are critically important in biomedical science, but as adjuncts to, not substitutes for, studies of animals. Animal studies remain the crucial linchpin between the test tube or tissue culture and the patient.

In research on Alzheimer's disease, for example, studies of aged monkeys are helping to identify specific brain regions lacking crucial neurochemicals. The information makes possible rapid and efficient efforts, using test tube and computer models, to develop medications to offset the chemical deficiencies. Promising drugs then will require animal testing for safety before they can be given ethically to patients.

A third tactic used by animal activists -- one that I know through personal experience -- is the harassment of those who speak out in defense of animal research. Techniques of intimidation include slander, physical threats and vandalism.

Animal rights activists may imply that they are not really opposed to all animal studies, but that they merely want the research community to make a few concessions in the interest of animal welfare. In fact, they are vehemently opposed.

Also, in fact, the research community already holds the "middle ground." In the animal rights debate, the opposite extreme of an animal rights activist would be a scientist who treated laboratory animals as hardware, who had no sense of moral obligation to treat them humanely. This hypothetical scientist, needless to say, would be ineligible for a federal research grant.

I don't challenge the right of animal activists to subscribe to their philosophy. But I object strenuously to their efforts to disguise that philosophy in pseudo-scientific arguments that are intended to mislead the public.

Also, I challenge the handful within my own profession who, when attacking animal research, claim to speak for the nation's physicians. In fact, fewer than half of 1 percent of all doctors are part of the animal rights movement. Virtually all physicians, along with membership of all of the major scientific organizations and voluntary health groups -- including, most tellingly, patients' self-help groups -- are unwavering in their support of the role of animals in biomedical science.

During a recent visit with an elderly couple -- I've treated the woman's depression successfully for many years -- I learned that she now has been stricken with Alzheimer's disease. "She's lost her humanness," her husband said to me tearfully.

I am confident that, with continued research, including animal studies, medicine is poised to make a leap in our understanding and capacity to treat Alzheimer's comparable to that in manic depressive illness. For now, however, as we accumulate knowledge through research, I again am humbled by my helplessness in the face of this tragic disease.

Frederick K. Goodwin, MD, is administrator of the Alcohol, Drug Abuse and Mental Health Association.

Second Opinion is a forum for points of view on health policy issues.