It was late evening on a pleasant fall day and retired schoolteacher Lyma Mae (Sherry) Reed, 85, was sitting on the sofa in her Rockville apartment. Her husband, former real estate salesman Alva J. Reed, 83, was seated next to her reading a book.

"She decided to get something from the coffee table," Al Reed said, "and she fell and rolled against the buffet."

Although the fall, a result of Alzheimer's disease, did not seem severe at first, it soon became apparent that Sherry Reed would need a considerable amount of care. This marked the beginning of an unfamiliar crisis for the Reeds. Now they may need help. And, for the first time, they may not be able to pay for it, particularly because Medicare does not cover the costs of long-term care.

Sherry Reed is one of about 2.5 million Americans afflicted by Alzheimer's disease, including about 20,000 in the Washington area. Once mistakenly thought of as simply "senility," Alzheimer's disease is an incurable disorder that begins gradually with forgetfulness but leads to loss of body control -- leading to falls such as the one Sherry Reed had two weeks ago -- and eventually to death.

Efforts by families and medical officials to focus public attention on the disease in the past several years have made Alzheimer's disease practically a household word. And last week President Reagan declared November as National Alzheimer's Disease Awareness Month.

Because of the increasing elderly population and the high financial risk the elderly face for long-term care, Congress has been studying the problem and debating possible actions. The House Select Committee on Aging has scheduled a hearing today on the issue.

With the aging of the population and with no significant medical breakthrough, the problem of Alzheimer's disease is growing, officials say. Some medical specialists estimate that more than 11 percent of the population older than 65 years of age may be afflicted by the disease.

Al Reed said last week that he does not want sympathy and would "rather die than have someone come in here and say, 'Reed, here's $100.' " But he concedes that he is not physically or financially able to provide all of the care that his wife now needs.

Last week, the Reeds needed a nurse to come to their apartment and feed, bathe and tend to Sherry while he recovered from the strain of constant caregiving. The cost for the nurse was $175 a day -- nearly $1,000 for the week.

"We can't keep that up very long," said Reed. "At the rate things are going, I will be broke in three or four weeks."

What has happened to the Reeds in the days since her fall shows how quickly families -- and especially the elderly -- can be overwhelmed and even impoverished while providing long-term care for a family member.

"This is an example of {what can happen to people who have} worked hard to take care of their family and themselves all their lives," said Gail Ewing, a spokesman for the Washington chapter of the Alzheimer's Disease and Related Disorders Association. "Suddenly they realize their best-made plans weren't enough, that insurance options weren't there and that Medicare doesn't provide the money needed. It makes for the humiliation of very proud people."

Ewing said that a recent survey of the families of Alzheimer's victims and those who work with the families indicates growing concern over the financial implications of the disease.

"Families struggling with this often don't know where to go for help," Ewing said. The Alzheimer's association is one of the groups attempting to provide emotional support as well as practical guidance and referrals, she said, and it tried last week to help the Reeds locate a service suitable for their needs.

"But there is very little available for long-term care," Ewing said.

For Al Reed, the financial facts tell the story.

"Sherry has a $300 monthly pension from teaching school in Montgomery County," he said. "With that and Social Security, we have about $1,500 a month."

Rent for their Grosvenor House apartment, two floors beneath their daughter's apartment, is $950 a month, including utilities. That leaves $550. "That's enough -- we can just eat and sleep," Reed said. Groceries cost the couple about $300 a month and medication about $150. The balance goes for miscellaneous expenses, such as the $150 he spent last month on tires for their 10-year-old car and medical bills that are not covered by Medicare.

For anything else, he dips into their savings, now down to $6,000.

The Mormon church, to which Reed and his wife belong, has offered to pay the nursing bill for last week, he said, "but I don't want a handout."

Al and Sherry Reed met 63 years ago on a Navajo Indian reservation in Gallup, N.M., where they were employed by the U.S. Interior Department. He was a cowboy from Colorado hired to work with the Indian youths and their horses. She was a teacher from Alabama assigned to teach the Indian children.

They were married Labor Day 1925 -- on the reservation.

The Reeds settled in Montgomery County in 1942 with their daughter Beth. Sherry Reed taught fourth grade at Whittier Woods Alternative Center and at Bannockburn Elementary School. Al Reed went into the real estate business and "was on the way to becoming a millionaire" when he had a heart attack in 1967.

Reed said that he began noticing changes in his wife's behavior about 10 years ago, about the time they moved into Grosvenor House. Three years ago he realized that "it was necessary for me to take over, because she would go in the kitchen and turn on the gas full blast and forget it. So I took over the entire work. Cooking. Cleaning. Taking care of her like she was a baby."

That includes bathing her, changing her clothes and her bed linens, providing around-the-clock attention, he said.

But in the past four months, Sherry Reed's condition has deteriorated. She has had trouble sleeping, and, because she has lost interest in food, her weight has dropped from about 130 pounds to about 95. At the same time she has been increasingly frustrated by her inability to remember.

"She calls me and I go and hold her hand," Reed said. "She will say, 'Come on, let's go, Al, come on, let's go Al.' And her muscles tense up."

Reed said he has been getting up three and four times a night to respond to his wife's calls for attention.

"She would doze for an hour and then wake up," Reed said. "The minute I would start reading, it seems like she would wake up and say, 'Al, Al, what are you doing? Sit here and talk to me.' So I console her until she goes to sleep.

"I can't give her attention now," Reed said. "I am just about played out physically."

Reed said he does not want put his wife in a nursing home. "I don't want her to become a number," he said.

He is not sure what the future holds.

"I am afraid from the looks of things she will be bedridden," he said. "I have tried to tell everybody I don't want her to suffer for anything, but I don't want to try to find ways to delay her ending. I think nature should take its course."