RALEIGH, N.C. (AP) _ Calcium channel blockers, a widely used and controversial treatment for high blood pressure, may be associated with brain damage and memory loss in the elderly, a new study suggests.

Research performed on patients in four states already taking drugs to control hypertension found those using CCBs and certain diuretics had more brain abnormalities and lower scores on mental tests than those taking other common medicines.

The study, released today and published in the December issue of the Journal of the American Geriatrics Society, is the latest in the past two years to suggest CCBs may cause health problems for the estimated 6 million Americans who use them.

However, other reports have reached conflicting conclusions about the effects of CCBs, including whether they raise the risk of cancer. Even the latest study's lead researcher, Dr. Susan Heckbert, conceded more work needs to be done.

``This is an interesting and important finding but there needs to be other studies performed on the issue,'' said Heckbert, of the University of Washington. ``The present study cannot determine whether (CCBs) caused those abnormalities or whether they were present before patients took the drugs.''

Calcium channel blockers changed the movement of calcium in and out of cells, reducing blood pressure levels and theoretically reducing the risk of heart attacks and strokes. They are sold under such brand names as Norvasc, Adalat, Cardizem and Procardia.

In the latest study, researchers took brain scans of 1,268 patients being treated for high blood pressure and already using at least one anti-hypertension drug. The participants, all at least 65 years old, also took a test designed to determine intellectual ability.

Patients taking calcium channel blockers and loop diuretics had more ``white matter hypersensitivities'' spotted in scans than those taking beta blockers and thiazine diuretics. Such abnormalities have been linked in previous studies to high blood pressure and impaired intellectual function, the report said.

The older the patient, the higher the white matter and the lower scores they received on the mental tests. But other things being equal, those taking calcium channel blockers and loop diuretics also had lower scores than those who took the comparable drugs.

Beta blockers and thiazine diuretics are most often the drugs of first choice prescribed by physicians for high blood pressure, while loop diuretics are used by patients already with advanced heart disease, Heckbert said. Diuretics spur the excretory process.

Dr. Richard Havlik with the National Institutes on Aging said in a journal editorial that the results raise the possibility that blood pressure has an adverse effect on a patient's brain.

``However, because of the possible unknown selective factors in this study, watchful waiting for future results and additional research is the order of the day before translation into clinical practice is appropriate,'' he wrote.

Still, Dr. Curt Furberg, a longtime critic of CCBs, said the results indicate that not enough research has been performed on the drugs despite widespread use since the 1980s.

``This is yet another problem to be added to the list caused by calcium channel blockers,'' said Furberg, of Wake Forest University Baptist Medical Center and a study researcher. ``The problem is that these and other newer drugs lower high blood pressure but were never properly evaluated for long-term safety.''

A cardiologist not involved in the study said the results, while interesting, still need to be viewed with caution.

``It's not unusual that people with hypertension find something like white matter damage in older people,''' said Dr. Melvin Cheitlin at San Francisco General Hospital and an executive committee member of the council on clinical cardiology of the American Heart Association.

``The question is more important whether the white matter damage was present in those who showed decreased performance,'' he said. ``There needs to be a lot of caution before doctors stop treating patients the way they do right now.''

The study's participants were gleaned from a larger Cardiovascular Health Study, which is designed to follow the natural progression of heart disease and stroke among older people.

The CHS involves nearly 5,900 people ages 65 and over selected at random between 1990 and 1993. People were chosen in Forsyth County, N.C., Sacramento County, Calif., Washington County, Md., and Pittsburgh.