Long before he was diagnosed with Alzheimer 's , Ronald Reagan 's speech may have contained clues to his worsening mental state . This is according to US scientists who have found subtle changes in the former president 's speech during his term in office from 1981 to 1989 . Reagan was diagnosed with Alzheimer 's in 1994 , and always maintained that he would resign from his post if his mental health went into decline . Scroll down for video . Long before he was diagnoised with Alzheimer 's , Ronald Reagan 's speech may have contained clues to his worsening mental condition , according to a new study by the University of Arizona . This image was taken in 1991 in California , just three years before the President was diagnosed with dementia . Early detection could slow the progression of the disease before it severely damages the brain . Ronald Reagan died at the age of 93 in 2004 . In 2010 , a book marking the 100th anniversary of his birth included claims by his son Ron , that he saw early signs of dementia in 'an out-of-touch president ' during the 1984 campaign . He says he saw those signs again in 1986 where he claimed his father could not remember the names of the familiar California canyons he was flying over . This did n't stop his adversaries claiming his tendency to forget names and make contradictory statements was the result dementia . Now researchers at the University of Arizona believe Reagan was suffering from the early onset of Alzheimer 's while acting as president . They came to the conclusion after comparing transcripts of 46 news conferences that Reagan held to the 101 sessions George H. W. Bush held in his term . 'Key word counts previously associated with cognitive decline in Alzheimer 's disease were extracted and regression analyses were conducted , ' the authors wrote . Reagan used words such as 'thing ' as a trigger to recall the correct words more often Bush . He also used more repetition . The team used a new algorithm based on a technique used by others to analyse changes in writing by novelists , according to a report in the New York Times . 'President Reagan showed a significant reduction in the number of unique words over time and a significant increase in conversational fillers and non-specific nouns over time , ' the researchers said . 'There was no significant trend in these features for President Bush , ' they added . The findings , published in the Journal of Alzheimer 's Disease , do not conclusively prove that Reagan had dementia that affected his judgment as president . The researchers came to the conclusion after comparing transcripts of 46 news conferences that Ronald Reagan ( right ) held to the 101 sessions George H. W. Bush ( left ) held in his term . Reagan used words such as 'thing ' as a trigger to recall the correct words more often Bush . He also used more repetition . But the scientists involved in the project hope the technique will help reveal signs of Alzheimer 's and other neurological diseases much earlier . Early detection could slow the progression of the disease before it severely damages the brain . Ronald Reagan died at the age of 93 in 2004 . In 2010 , a book marking the 100th anniversary of his birth included claims by his son Ron , that he saw early signs of dementia in 'an out-of-touch president ' during the 1984 campaign . The telltale signs of Alzheimer ’ s can be seen in people as young as 20 , research shows . The ‘ unprecedented ’ finding suggests that the disease starts to eat away at the brain half a century before symptoms develop . This is a ‘ much younger age than the scientists ever imagined ’ . The discovery raises the prospect of giving people drugs in the very earliest stages , when it is easiest to treat , and even stopping the disease in its tracks . However , British experts cautioned that the research is still at an early stage . Crucially , it isn ’ t known how many people who have the early signs of Alzheimer ’ s in their brains in their 20s will go on to develop the disease . Alzheimer ’ s and other forms of dementia affect more than 800,000 Britons and , worldwide , the number of sufferers is predicted to treble to 44million by 2050 as the population ages . He says he saw those signs again in 1986 where he claimed his father could not remember the names of the familiar California canyons he was flying over . While some people suggest they knew Reagan had the disease while in office , his four White House doctors said they saw no evidence of it . Alzheimer 's is an incurable neurological disorder which destroys brain cells . Mr Reagan informed the nation in a hand written letter when he was formally diagnosed . 'Had the diagnosis been made in , say , 1987 , would he have stepped down ? ' , Ron asks in the book . ' I believe he would have ' . Ronald Reagan ( right ) died at the age of 93 in 2004 . In 2010 , a book marking the 100th anniversary of his birth included claims by his son Ron ( left ) , that he saw early signs of dementia in 'an out-of-touch president '
he compiled transcripts of 46 conferences that Reagan held . They compared these to sessions George H. dick ##son held in his basement . he used words such as ' thing ' to help him recall words more often . He also used more repetition , which may be an early sign of Alzheimer 's .