A British specialist in dementias asks family members, "How many kettles have you had burned out?" to try and discern whether his patient has Alzheimer's disease. Or, he might ask, "Do you ever feel like throttling the patient?"

An American psychiatrist wonders if the patient becomes especially disoriented on a trip or if the bookkeeper in the family is suddenly keeping a checkbook that is "no longer interpretable."

Both of them demonstrate the importance of family interviews for the general practice physician to begin evaluating a patient who comes into the office with symptoms of dementia.

At a time when "Alzheimer's disease" has become a buzzword, almost a pop diagnosis for patients whose memories and ability to function appear impaired, there is beginning to be some concern that a number of other underlying causes of dementia are being missed.

Sometimes these causes are reversible. Sometimes the seemingly relentless decline can be arrested. Most patients with symptoms of dementia have Alzheimer's disease or the so-called multi-infarct dementia or a mixture of the two. At this point Alzheimer's cannot be reversed or halted, and there is controversy over whether or not the dementia caused by repeated cerebral clots or hemorrhages can at least be stemmed.

However, there are possibly thousands of older people who are having drug reactions, metabolic or nutritional disturbances, benign tumors or a dozen or more other conditions in which the behavioral manifestations of dementia occur. Some of them, such as dementia associated with Parkinson's disease, are usually irreversible too, but many of them are not. Some conditions, such as depression, may be virtually cured.

A National Institutes of Health consensus development conference held in Bethesda last week attempted to cope with the problem of helping the family doctor spot the more easily treated causes of dementia.

It turned out to be no easy task.

Many specialists are involved in the diagnosis and treatment of dementias: geriatricians, because dementias strike mostly older people; neurologists, because dementias are diseases affecting the brain; psychiatrists and psychologists, because dementias affect the mind and behavior. Also, there are radiologists, because new techniques to produce pictures of the brain hold immense promise in diagnosing Alzheimer's disease and in differentiating between it and other brain disorders.

Still, the family doctor is the first line of defense, and what the family sees is a crucial component of what the doctor will decide is the diagnosis. ::

The consensus statement, issued July 8, is designed to provide family doctors all over the country with a partial list of the many potential causes of dementia and some specific behaviors that are more often characteristic of Alzheimer's than of other disorders. The consensus statement also lists a number of disorders that might be causing the dementia if it isn't Alzheimer's, along with some ways to find out the underlying cause.

(The statement did not go through its final revisions, in part because the expert panel became stuck in an elevator in the NIH main building during much of the time allotted for fine-tuning the guidelines.)

Still the committee of experts, headed by Dr. Joseph M. Foley, neurologist and professor emeritus at Case Western Reserve University medical school in Cleveland, con- ceded that at this stage there are no hard and fast rules in diagnosing the different causes of dementia.

Speaker after speaker echoed the words of Dr. Burton V. Reifler, who told the panel that the history from the patient's family is most critical.

"I think it is more important than a CT scan or laboratory evaluation or electroencephalogram," he said. "The patient's history is the single most important element in making a diagnosis." Reifler is chairman of the psychiatry department at Wake Forest University medical school and director of the just-announced Dementia Care and Respite Services program of the Robert Wood Johnson Foun- dation, co-funded by the Alzheimer's Disease and Related Disorders Association.

At the same time, some specialists were concerned that the consensus statement plays down the role of some of the new high-tech imaging machines that are proving useful in diagnosis. These techniques include computer axial tomography (CT or CAT scans), positron emission tomography (PET scans) and the newest entry in the field, single photon emission computed tomography (SPECT).

Dr. Robert P. Friedland, chief of the section on brain aging and dementia of the Laboratory of Neurosciences, in the National Institute on Aging, says that he and his colleagues "find PET to be an excellent, reliable and sensitive diagnostic test for Alzheimer's disease and for distinguishing it from other things." Friedland reported to the panel that of 60 patients diagnosed by PET scan as having Alzheimer's, five have died, permitting autopsy confirmation in each case.

Panel members noted that PET, which requires an on-site cyclotron to produce a fast-decaying radioactive isotope, is available only at certain research institutions.

Some specialists at the conference also suggested that other scans, such as CT and magnetic resonance imaging (MRI), have been too often used routinely when, because of their expense and their only occasional usefulness, they should be reserved for use only when all other diagnostic tools are exhausted.

Nevertheless, Dr. David A. Drachman, chairman of the department of neurology at the University of Massachusetts Medical Center in Worcester, said this: "All of us are getting exceedingly bored at ordering scans, all these tests and studies. But consider their cost effectiveness. The average cost of a complete workup is approximately $1,500 for an individual. A nursing home is about $30,000 a year. If you figure the average rate of finding a treatable, reversible, arrestable disease is something like 10 percent, you are far, far ahead. It is boring. But it pays."

Virtually all of the speakers referred to some slowing down of mental and intellectual functions in the course of normal aging. This makes it all the more difficult to distinguish between disease and the impairment people encounter as they get older.

"The first thing we have to point out is that at the age of 90, the only normal thing is to be dead," Drachman said. "So we're going to have serious problems in determining where it is that normal aging ends and dementia begins."

More Information

Treatment programs for Alzheimer's disease have openings for patients. National Institute on Aging. Phone: 496-4754. Dementia Care and Respite Services information. Linda Orgain, Robert Wood Johnson Foundation, P.O. Box 2316, Princeton, N.J. (609) 452-8701. Susan Gannon, Alzheimer's Disease and Related Disorders Association, (312) 853-3060.