Until recently, a patient like Carolyn E. Hoard would never have been told she was progressing toward Alzheimer's disease. A 61-year-old mental health counselor in Kittanning, Pa., she reported nothing more than a mild loss of memory, particularly when it came to recalling what someone had said in conversation a few minutes ago. Her first neurologist told her she was fine.

But the memory lapses persisted, and Hoard went to a second neurologist, who gave her the news she had been dreading: She suffered from mild cognitive impairment, usually the first sign of Alzheimer's disease.

The term is new, having entered the vocabulary of memory specialists in the late 1990s. Now, more and more doctors, combining tools as sophisticated as brain imaging and as simple as a short test of word recall, are making the diagnosis. Researchers and drug companies say the new category will enable them to track the progression of Alzheimer's disease and understand it better. They are already testing a wide array of treatments in these patients - from vitamins to hormones to new drugs, as well as drugs already approved for Alzheimer's.

"If we, in fact, can intervene at this earlier stage and alter the course of the disease, that would have a big impact on quality of life," said Dr. Ronald Petersen, who directs Alzheimer's research at the Mayo Clinic in Rochester, Minn.

The signs of mild cognitive impairment are an inability to form memories for events that just happened and a slight shrinking of the hippocampus, the area of the brain where these memories are laid down. On a memory test, a patient might be able to repeat a string of unrelated words - red, Oldsmobile, cabbage - but then fail to recall even one of them 10 minutes later.

No one knows how many people have the condition. While an estimated 4 million Americans have Alzheimer's disease, studies to determine the incidence of this milder disease that precedes it are only starting.

But doctors say the new diagnosis is changing the landscape of Alzheimer's, giving rise to a growing class of patients with what Dr. Steven DeKosky, director of the Alzheimer Disease Research Center at the University of Pittsburgh, calls a sword of Damocles over their heads.

Inexorable progress

Their prognosis is not good. Mild cognitive impairment might be caused by other disorders, especially depression. But when no such cause is found, it has been shown in studies to lead to full-blown Alzheimer's, with its additional impairments in reasoning and thinking, in at least 80 percent of cases.

Patients with mild cognitive impairment progress to Alzheimer's at a rate of 12 percent to 15 percent a year, the studies show; for people of similar ages without mild cognitive impairment, the rate is about 1 percent a year. Nothing has been shown to slow brain-cell death.

But doctors and patients say the new diagnosis holds one other bright spot: It is giving a new, first-person voice to Alzheimer's, enabling patients to talk about the disease before it robs them of understanding.

"The problem with dementia has always been that it is so foreign and so frightening that the impulse is to recoil from it," said Dr. Alan Dienstag, who coordinates psychology research for the New York chapter of the Alzheimer's Association.

Now, patients whose impairment is relatively mild are starting to tell their stories, he said. "We're on the cusp of seeing a really substantial change."

Petersen, of the Mayo Clinic, says mild cognitive impairment was discovered almost by accident. His group was studying patients who came in for routine care, looking for those who had complained, or whose family members or doctors had noticed, that they were getting forgetful. The clinic doctors discovered that their memory impairment was very specific - their only problem was remembering experiences of the last few minutes or hours or days.

In a typical test for mild cognitive impairment, a patient is asked to repeat a string of unrelated words. The tester goes on to ask other questions: Multiply 5 by 13, name the first president and the current president. At the end, the patient is asked to recall the unrelated words.

A person with normal memory might falter, but given a hint (for example, that one of the words was a color) might reply, "Oh, yes, a red Oldsmobile with a cabbage inside."

But a person with mild cognitive impairment is not helped by hints, said Dr. Jeffrey Cummings, director of the Alzheimer's Disease Center at the University of California, Los Angeles, "because the memory was never stored."

People with Alzheimer's disease are much more impaired. They might have trouble interpreting what they are reading, or writing a grammatically correct sentence. They have trouble concentrating, reasoning and doing simple math problems. They have trouble in their daily activities, often getting lost when they drive a car.

Alzheimer's can also rob patients of self-insight - the ability to recognize what is wrong with them. Many medical investigators believe that this is a consequence of deterioration in the cells in the brain's temporal lobe, where insights are formed.

But patients with mild cognitive impairment have insight, and they and their doctors say it can be a curse. They know too well what the future might hold.

"Many have family histories, and they have watched the disease process play out in close family members," Petersen said. "That's very frightening. We see depression, anger, 'Why me?' We see anxiety develop because people start to lose their grasp of things."

Many take drugs that have been approved for Alzheimer's or take substances such as vitamin E that researchers hope might help. But for now, Petersen said, "there have been no clinical trials that demonstrate that anything works or doesn't work - they are all under way."

A lonely life

Yet patients like Hoard can describe their lives in a way that people with Alzheimer's cannot. Life, as she describes it, can be achingly lonely. Even keeping up with a conversation can be a struggle because she cannot remember what was just said.

"You feel like no one really understands," she said. "They say: 'Everyone forgets. There's nothing wrong with you.' You just want to go: 'But you don't understand. It's not that kind of thing.'"

In a telephone interview, Hoard explained that conversations could be difficult and asked to send a letter about her experiences.

"Just when you want to assert yourself and have some good confident 'self-talk' going," she wrote, "you 'forget' some important detail or realize you've asked your spouse or friend the same question three or four times and they are tired of giving the answer over and over! You want to hide away somewhere and just cry sometimes."