WHAT WILL it be like to be a medical patient in the year 2010? Judging from reliable contemporary indicators, it will be dramatically different -- and not necessarily better.

For one thing, private practitioners will have gone the way of the dinosaur, with almost all doctors working on salary. A national health corps will be in place, thanks to an idea enthusiastically adopted in the early '90s in response to the closure, for want of patients, of between 10 and 20 percent of the nation's private hospitals. These will be purchased by the U.S. government and staffed by physicians who initially will care for Medicare patients. Later, additional classes of patients will be targeted, most notably the 300,000 to 450,000 cases of AIDS expected nationwide by the year 1991.

These changes will mark a revolution in medical practice. Doctors trained in the traditional fee-for-service model will retire or abandon medicine. In their place will be younger doctors who attended medical school in the late '80s and early '90s and who entered the profession with more modest expectations in regard to income and prestige. Three pivotal influences will bring this about: The malpractice crisis. During the '80s, state legislatures will give lip service to the idea that the public welfare is ill-served by physicians practicing in an atmosphere of real and imagined financial disaster; but little will be achieved. Among other reasons, legislatures contain a large number of lawyers; and medical malpractice is a lucrative source of income for the legal profession. The traditional animus between lawyers and doctors will do nothing to ease the impasse.

Finally, in the '90s public impatience with the lack of medical care in the areas of emergency medicine, orthopedics, neurosurgery and obstetrics will force reluctant legislatures to put caps on recovery for "pain and suffering"; limit contingency fees so that the vast bulk of successful recoveries passes to the patient and not the lawyer; and mandate that claims not involving death or irreversible injury be submitted to arbitration before the filing of a lawsuit. But these actions will prove too little too late. By this time the most talented students will be passing up medicine for other professions which offer greater incomes, independence and, most importantly, prestige. The bureaucratization of medicine. With more "red tape," mounting numbers of insurance forms, review boards and insurance-company inquiries into the appropriateness of medical treatments for specific patients, physicians in the '90s will become increasingly defensive and unhappy. Job dissatisfaction will reach an all-time high in 1995, a development predicted in 1987 by a group of health-care experts surveyed by the American College of Health Care Executives and Arthur Andersen & Co. The AIDS epidemic. Despite early warnings, the health-care system will prove woefully inadequate. In 1991 one-half of all the hospital beds in New York City will be occupied by AIDS patients. This will make it extremely difficult even for university hospitals to attract top-flight (or even acceptable) interns and residents. Most of the brighter students will opt for smaller cities and rural areas where they will encounter other illnesses.

Meanwhile, urban hospitals will be paying astronomical salaries to attract doctors willing to care for AIDS patients. By the early '90s, those patients will so far outnumber available physicians that the federal government will intervene. Doctors who refuse to treat AIDS patients will be brought before review boards, often with the recommendation that their licenses be revoked. The patient/doctor relationship, traditionally voluntary, will become increasingly controlled and in some instances even compulsory. For the few doctors who remain in private practice, fees will be strictly regulated. All services, from open-heart surgery to flu shots, will be assigned a specific unit value easily converted into dollars. Eventually a paradox unique to American medicine will arise: The youngest, most recently trained doctors will assume leadership positions in treating the nation's patients.

Nurse midwives will be able once again to get reasonably priced malpractice insurance; and with fewer physicians, more nurse practitioners and physician's assistants will diagnose and treat "routine" illnesses. The larger health-care organizations will be quick to see the advantages of employing lower-paid paraprofessionals.

In addition, computerized "expert systems" will aid in diagnosis. The patient with a headache will interact via home computer with software which mimicks the diagnostic process used by doctors. Depending on his response to key questions (Do you vomit? Experience visual blurring?), the patient may be asked to come in for a further workup. "Not only will sophisticated databases aid in difficult diagnoses, but more immediate contact will be possible with patients who need a high degree of monitoring," says Dr. Stewart A. Wesbury Jr., president of the American College of Health Care Executives. "This will be particularly valuable in rural medicine and in cases in which treatment will benefit from periodic checking." Progress and Problems Technology and applied research will have advanced substantially by 2010. But the advances will be fraught with legal and moral conundrums. For example, scientists will be able to pinpoint the genetic troublespot for the majority of the 4,000 inherited human diseases using "gene probes" -- short stretches of DNA that attach to specific defective genes.

At the moment scientists can analyze the DNA of a fetus only a few weeks old and determine whether it has inherited sickle-cell anemia, thalassemia or other disorders of hemoglobin. By the year 2000, it will be possible to isolate and analyze genes which may increase a person's susceptibility to a particular illness. Not every smoker gets cancer of the lung; not every person with high blood pressure or elevated cholesterol dies of a heart attack. At present, physicians can only speculate about which patients will suffer those consequences. With the development of additional gene probes it will become possible to translate "susceptibility" and "propensities" into actuarial formulas.

For several years, companies in the United States, Japan and Britain have been engaged in a race to map the three-billion-unit sequence of chemical bases that make up the DNA comprising the human gene. By the year 2000 this task should be completed at a cost of about $3 billion. But what is to be done with the information? In many cases, illnesses will be predicted for which preventative measures or treatments won't be available. Or suppose a fetus inherits a tendency to high blood pressure. By itself, that may or may not lead to severe health consequences. Should the doctor tell the parents? Few parents would elect to abort a fetus at risk for hypertension; others with a "consumer" orientation ("Why settle for a defective product?") might think otherwise.

Even more ethically ambiguous will be fetal manipulation -- now experimental, but probably available in 2000 -- during the pre-embryonic period, the first two weeks after the human egg is fertilized. Since the egg doesn't attach to the womb during the first six days after fertilization, it could be removed, placed in a culture dish and monitored. Inherited metabolic defects could be detected at the earliest possible moment; and only those eggs free of disorders would be returned to the uterus. Or the pre-embryo can be biopsied at an area, the second polar body, which serves as little more than a reservior for surplus DNA. Analysis could reveal, for example, the presence of an extra chromosome 21 associated with Down's Syndrome.

Such diagnosis could assure at-risk couples that a genetically normal egg would be implanted, greatly reducing the risk of an impaired child without involving abortion. The defective egg is never implanted, never grows to the embryonic stage and, therefore -- some would hold -- never achieves independent existence and personhood. But even granting this highly arguable point, what will be the limits of parental choice? Forget about "defects." What should the obstetrician say to the couple who, for instance, prefers a boy over a girl?

It's likely that by the year 2000 such agonizing issues will be decided by a Statutory Licensing Authority which will certify institutions and doctors working with pre-implantation eggs. Last year the British government took the first step, proposing to Parliament that criminal penalties be invoked for doctors or researchers who fail to conform to guidelines dealing with the manipulation of the genes of a human embryo. Eventually governments will decide that such morally and ethically loaded issues cannot be left to "free-market" negotiations. Too much is at stake to allow human reproduction to be dehumanized, as it has been in the 1980s, by whackos, cranks and publicity-seekers.

Advances in genetics will only be exceeded by new insights into the brain. Computer-assisted devices will enable neuroscientists to display in real time brain activity patterns corresponding to specific mental states. Everything from daydreaming to computational analysis will be correlated with measures of glucose, oxygen and blood flow. Magnetoencephalography -- the detection of the magnetic field produced by electrical current within the brain -- will make it possible to study patterns of communication among selected populations of neurons. In answer to the question, "Is such-and-such a world leader showing signs of senility?" scientists would compare the leader's neurochemical and neuroelectrical profiles with normal individuals of a similar age. Marvels of Medication By 2010 it is likely that new drug treatments will be capable of strengthening memory and impeding senility. Many drugs will be delivered in novel forms: inhaled or implanted beneath the skin as "pulsatile" systems which work in concert with the body's own circadian rhythms. At present, medication levels vary widely at different times of the day, thanks to brain-regulated variations in blood constituents. A "pulsatile" system will make it possible to provide the maximum amount of drug at the most propitious moment.

Among the more exciting drugs will be new pain-killers and tranquilizers which do their job without producing euphoria or addiction. (One such tranquilizer, BuSpar, went on the market last year.) These drugs will be harder to synthesize but should be in place by 2010 since neuroscientists have learned more about the brain's pleasure centers and their role in addiction in the past five years than in the previous 30. Moreover, it should be possible to deliver needed neurochemicals and drugs via indwelling canulas (tube-like extensions leading from the scalp to specific areas of the brain), thereby avoiding the intolerable and sometimes irreversible side effects which can result from taking potent brain-altering drugs by mouth.

Expect that treatments will become more reliable as such illnesses as "schizophrenia" and "multiple sclerosis" become better understood not as monolithic entities but as clusters of illnesses, each of which may require a different treatment. The stimulus for these advances is likely to come not just from neuroscientists but from computer specialists who already are modeling important aspects of brain function. For instance, neuronal groups, not single neurons, are presently becoming the prime candidate for the much sought-after "fundamental unit of brain organization." Such neuronal groups are thought to be only about 50 micrometers wide, too narrow to be studied by currently available neuroscientific probes; but computers can model them easily and indeed have already produced representations that closely resemble results gleaned from animal research that, for ethical reasons, couldn't be carried out in human subjects (since it involves the deliberate destruction of small areas of the brain).

Brain transplants -- the insertion of tiny portions of the brains of fetuses into adult brains -- will provide treatments if not functional "cures" for persons afflicted with brain diseases marked by deficiencies in specific neurotransmitters. This has already been accomplished in 1987 with patients suffering from Parkinson's Disease, a degenerative nervous system illness marked by a deficiency of the neurotransmitter dopamine.

Finally, don't expect a cure for cancer (a huge chunk of the cancer research budget will be shunted into AIDS research in the early 1990s) or for heart disease, diabetes and hypertension. There are simply too many interrelated contributing variables (diet, heredity, smoking and drinking patterns, exercise and so on). But there will likely be better and more reliable artificial organs, making economic barriers less determinative of who will live and who will die.

All in all, expect that medicine in the year 2010 will bring technological innovations that may out-pace our abilities to devise sensible, fair and ethical uses for them. One thing is certain: More will be required from all of us than simply a "gee whiz."