Former President Ronald Reagan was diagnosed with Alzheimer's in 1994 - five years after he left the White House - but a new study suggests his speaking patterns during his two terms in office may have hinted at the disease.
Scientists looked at transcripts from news conferences that Ronald Reagan and George H.W. Bush held during their terms in office. They discovered that Reagan exhibited subtle changes in speaking patterns during his presidency that are linked to the development of dementia.
Reagan was more repetitive with his words and substituted nonspecific terms such as "thing" for specific nouns. He also used significantly fewer unique words over time.
Reagan exhibited these changes more toward the end of his presidency.
Bush, who has not been diagnosed with Alzheimer's, did not show the same subtle changes in his speech.
Ronald Reagan and George H.W. Bush
Reagan's speeches may have shown early signs of Alzheimer's
President George H. Bush point to a piece of the Berlin Wall while visiting former President Ronald Reagan in Reagan's Century City office on Thursday, March 1, 1990 in Los Angeles. (AP Photo/Barry Thumma)
U.S. Secretary of State George Shultz, center, is escorted by President Ronald Reagan, left, and Vice President George Bush to the White House in Washington, D.C., Wednesday, Jan. 8, 1985, after his return from U.S.-Soviet arms talks in Geneva. (AP Photo/Barry Thumma)
Former President Ronald Reagan, left, his wife Nancy Reagan, new first lady Barbara Bush and her husband President George Bush, right, walk down the Capitol steps after the inaugural ceremony in Washington, D.C., Friday, Jan. 20, 1989. President Bush was sworn in as the nation's 41st president. The Reagans are heading to an awaiting helicopter to take them to Andrews Air Force Base, Md., and onto California. (AP Photo/J. Scott Applewhite)
Republican candidate for President Ronald Reagan, left, and his running mate George H.W. Bush answer questions during a press conference Friday, July 26, 1980. Reagan said the independent committees raising funds to help elect him president are "a hazard" that could cause a backlash against his candidacy. (AP Photo/Wally Fong)
Gov. Ronald Regan, the Republican Party's nominee for president and his vice-presidential nominee George H.W. Bush pause for photos as Reagan arrived Thursday,July 24, 1980 for meeting with Bush. The two will also hold joint meetings with members of both their political campaign staffs. (AP Photo/Wally Fong)
Republican presidential candidates Ronald Reagan, left, and George H.W. Bush, right, greet prior to their Thursday night debate February 28, 1980 on public television. Howard Baker and John Connally were also present at the debate at Columbia, S.C. (AP Photo)
President Ronald Reagan and Vice President George H.W. Bush meet with members of the U.S. Committee on Pacific Economic Cooperation on Tuesday, Sept. 18, 1984 in the White House Rose Garden in Washington. (AP Photo/Barry Thumma)
Pres. George H. W. Bush, right, presents former Pres. Ronald Reagan with the Medal of Freedom during a ceremony at the White House, Wednesday, Jan. 13, 1993, Washington, D.C. Reagan became the 302nd recipient of the nations highest civilian honor, the 38th such award of Bushs tenure in the White House. (AP Photo/Doug Mills)
Pres. Ronald Reagan, front right, and President-elect George H. W. Bush, walk toward the Oval Office at the White House, Wednesday, Nov. 10, 1988, Washington, D.C. Bush and Vice President-elect Dan Quayle, back right, met briefly with the President. Barbara Bush, center right, Nancy Reagan, center left, and Marilyn Quayle are also shown. (AP Photo/Bob Daugherty)
Pres. Ronald Reagan, center, grins toward President-elect George H. W. Bush, right, as Vice President-elect Dan Quayle looks on, Nov. 9, 1988, Washington, D.C. Also standing are Mrs. Nancy Reagan, left, Mrs. Barbara Bush and Mrs. Marilyn Quayle. (AP Photo/Bob Daugherty)
Pres. Ronald Reagan greets President-elect George H. W. Bush, left, upon his arrival to the White House, Wednesday, Nov. 10, 1988, Washington, D.C. (AP Photo/Charles Tasnadi)
Pres. Ronald Reagan, right, with Vice Pres. George H. W. Bush at back, talks to reporters at the White House as he and Mrs. Reagan prepare to leave for their trip to Europe, Friday, June 1, 1984, Washington, D.C. They will visit Ireland and London with a stop in Normandy. (AP Photo/Barry Thumma)
President Ronald Reagan, left, shakes hands with President-elect George H. W. Bush as First Lady Nancy Reagan looks at the White House prior to leaving for the Capitol for the inauguration of Bush as the 41st President, Friday, Jan. 20, 1989, Washington, D.C. (AP Photo/Doug Mills)
President Ronald Reagan with Vice President George Bush and wives Nancy Reagan and Barbara Bush attend the National Prayer Service in Washington on Sunday, Jan. 20, 1985 at the National Cathedral. At noon today President Reagan will be sworn to his second term as President at a private White House ceremony. (AP Photo/Ron Edmonds)
President-elect George Bush gives President Ronald Reagan a thumbs up as Reagan reacts prior to Bush being sworn in as the 41st president of the United States outside the Capitol, Jan. 20, 1989, in Washington. Behind Reagan is Bush's son George W. Bush. (AP Photo/Ron Edmonds)
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Reagan's mental state was a political issue even before he became president. His adversaries often claimed his tendency to forget names and make contradictory statements was a sign of dementia.
The study's authors note that the findings, which are published in the Journal of Alzheimer's Disease, do not prove that the late president had dementia that affected his judgement while in office. A writer for The New York Times also noted that doctors and key aides did not detect "any changes in his mental abilities while in office."
The researchers hope that this technique will help catch signs of Alzheimer's and other neurological disease earlier.