Police, family and others associated with the week-long search for a 71-year-old Bethesda woman found Monday in a Lord & Taylor store said they may never know whether the woman, still confused after her ordeal, spent the entire time lost inside the store.

Brigitte Pierre, who vanished Dec. 21 after keeping an appointment with a hair stylist at the Lord & Taylor store in upper Northwest Washington, was found a week later in a seldom-used stairwell of the store. She was being treated for mild dehydration yesterday at Sibley Memorial Hospital, and a spokeswoman said she probably would be sent home today or tomorrow.

Pierre's husband, her physician, a police detective and a Lord & Taylor vice president agreed it was possible she spent all or most of the week in the store at 5255 Western Ave. NW, but they said they could not be sure. They said her mental capacity began deteriorating months ago, and that she has little, if any, memory of her whereabouts in the last week.

A hospital spokeswoman said Monday that Pierre apparently had gone without food and water during the ordeal, but her physician said yesterday that test results showed she had consumed small amounts of each.

"How she got access to it is not clear from her, and it probably never will be," said Dr. Lawrence McDonald, who described Pierre as disoriented and unable to recall the day she disappeared.

McDonald said it was impossible for him to determine how much time, if any, Pierre spent outdoors. But he said her skin, which was not scraped or bruised, showed no sign of prolonged exposure to cold or wetness.

Lord & Taylor Regional Vice President Robert Morrison said he doubted if store officials would ever learn exactly what had happened. After Pierre was reported missing, he said, employes searched the store several times and looked at least twice in the stairwell where she was eventually found.

With Pierre safe, the police investigation of her disappearance has been closed. But Lord & Taylor has begun an internal review, Morrison said.

If she did spend a week in the store, he said, "I'd like to know why my security department didn't find her." But he said he held little hope of finding a conclusive answer.

The store does not employ overnight security guards, he said, but anyone wandering in Lord & Taylor after closing time would probably set off an electronic alarm. Morrison said Pierre could have spent much of the week elsewhere, and drifted back into the store, and then the stairwell, not long before she was discovered Monday.

Montgomery police Detective John McCloskey said that following media reports of the disappearance last week, he received "more than a dozen calls of potential sightings, from Falls Church all the way up to Gaithersburg." His supervisor, Lt. Robert Evans, said yesterday it would be pointless now for police to investigate whether the reports were accurate, or whether Pierre spent the entire week in Lord & Taylor.

Henri Pierre, her husband of 42 years, said he drove his wife to Lord & Taylor for her salon appointment about 10 a.m. on Dec. 21, and returned about 11:15 a.m., after she called him for a ride home. He said he and his wife follow that routine about once a month.

But that day she failed to meet him outside the store. When she was found about 6 p.m. Monday -- a week later -- in the stairwell, she said she was waiting for her husband and asked for a cup of tea.

Henri Pierre said his wife suffers from a disorder that often causes her to experience severe memory lapses.

"I'm afraid she has the symptoms of Alzheimer's disease, but the doctors say it is too early to tell," he said. After visiting his wife in the hospital yesterday, he described her as "very confused."

"She does not realize what happened," he said, "and it is very difficult for me to explain it to her."