Dr Butler's daughter Christine said that he died of leukemia at Mount Sinai Medical Center.

A gerontologist and psychiatrist, he was the founding director of the National Institute on Aging, one of the National Institutes of Health. He wrote several books on aging, including the 1976 Pulitzer-winning "Why Survive: Being Old in America."

Dr Butler coined the term "ageism," or age discrimination, in 1968, and led a task force that analysed the impact of age prejudice in a 2006 report, "Ageism in America." It addressed age discrimination in the workplace, elder abuse and the media's role in perpetrating such bias.

Dr Butler was founding chairman of the nation's first department of geriatrics, at the Mount Sinai School of Medicine. And he was founding president of the International Longevity Center-USA in New York City, a research, policy and education centre dedicated to the field of longevity and aging.

He was instrumental in research that established that senility was not inevitable with aging, but rather a consequence of disease, according to the longevity centre website. A study he led helped set the agenda for such concepts as "productive aging" and "successful aging."

He also is credited with the concept known as "life review," a therapeutic device people can use to reflect on their lives, said Ev Dennis, secretary of the longevity centre board.

At the time of his death, he was leading a committee on aging for the World Economic Forum.

A memorial service was planned for sometime in September, Ms Butler said.

Article from The Telegraph