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Dementia causes are easier to pinpoint

EDITOR'S NOTE: This weekly column by reporter Bill Kettler answers readers' questions about topics of general medical interest with information provided by doctors from PrimeCare, Jackson County's independent practice association.

A few years ago I remember hearing that Alzheimer's disease could not be verified until after a patient's death. Now we hear of people who have been diagnosed in the early onset of Alzheimer's. Is it diagnosed and differentiated from regular dementia by new tests? Also, what medications, if any, can slow its progress?

— Mary Ann J., Central Point

Physicians can make a diagnosis of Alzheimer's more confidently these days because they've learned it's by far the most common cause of dementia, says Dr. Steve Brummer, a Medford geriatrician.

"Dementia" is a broad term that physicians use to describe a general decline in a person's mental abilities, such as memory, learning and problem solving. Research studies have shown that the majority of people who have dementia are suffering from Alzheimer's.

Brummer notes, for example, that in one study, physicians did post-mortem examinations of the brains of 106 people who were suffering from dementia. Among those patients, 87 percent (92 people) were found to have the brain changes associated with Alzheimer's.

"Alzheimer's is regular dementia," Brummer says.

Physicians estimate that generally some 60 to 80 percent of all dementia patients have Alzheimer's. Stroke is the second leading cause of dementia, accounting for 10 to 20 percent of cases. A number of other neuro-degenerative diseases also are associated with dementia, but they occur much less frequently.

Brummer says physicians look at four criteria to determine whether a patient has Alzheimer's. First, the patient must display a continuing decline in cognitive function, that is, the ability to think and solve problems. The patient must also have impaired short-term memory, and the mental decline must not be related to some other disease, such as alcoholism, (which can cause memory loss and cognitive impairment).

Finally, the mental deficits must not occur solely while the patient is experiencing delirium, a condition in which a person experiences a sudden change in mental function that produces confusion and strange behavior. Delirium can be brought on by withdrawal of drugs or alcohol, so physicians need to eliminate those possible causes of delirium before they can make a diagnosis of Alzheimer's.

"People in delirium can look like people with dementia," Brummer explains, with one crucial difference. "When the delirium clears, (mental) function may return."

The human brain typically loses some of its edge as part of the aging process, and doctors have some fairly simple tests to determine whether a patient has normal brain function or some mild level of cognitive impairment. If a physician suspects Alzheimer's, the patient may be re-tested in six months to determine whether there has been further impairment. If the impairment increases over time, and there are no other likely causes, a diagnosis of Alzheimer's could be appropriate.

There are no drugs that cure Alzheimer's, but physicians have used drugs known as cholinesterase inhibitors to help patients try to improve memory and manage thinking problems.

So far, Brummer says, the average benefit of cholinesterase inhibitors is a small improvement in patients' cognitive function and their ability to perform ordinary daily activities.

"What we can say is that, on average, cholinesterase inhibitors produce a small improvement in cognition and the activities of daily living," Brummer says.

For people who already have moderate to severe memory loss and thinking problems, physicians may prescribe memantine, a drug that shows promise for slowing late-stage Alzheimer's.

Call Bill Kettler at 776-4492, or e-mail them to: bkettler@mailtribune.com or send them to: Mail Tribune, Ask Your Doctors, P.O. Box 1108, Medford OR 97501.