Barbara Walters Forgetful, Fear of Falling, Isolated

Barbara Walters, not just a legendary broadcaster but beloved in New York social circles, has been living her life within the confines of her New York apartment, showing significant signs of age and receiving almost no visitors ... TMZ has learned.

The 87-year-old icon has become increasingly forgetful and confused ... sources familiar with the situation tell TMZ.

She almost never leaves her apartment, we're told, because she has an intense fear of falling down and breaking a hip ... something that often results in a downward spiral for older people.

Barbara does not want to receive guests. We're told she has shut herself off to almost everyone at ABC, and she only sees a few people who have been close to her.

Barbara does have a trainer who sees her weekly.

As one source says, the effects of aging are clearly present.