During her time in power, Baroness Thatcher was renowned for her razor-like intellect and power-house memory.
But in a twist of fate, the former Prime Minister was destined to become one of the more than 820,000 people in the UK whose lives are blighted by dementia.
Although it has often been reported that she suffered from Alzheimer's disease, this has never been confirmed.
Alzheimer's is the most common of four principal kinds of dementia, affecting around two thirds of all those with the condition.
The second most common is vascular dementia, caused by reduced blood flow to the brain, followed by dementia with Lewy bodies and frontotemporal dementia.
All forms of dementia result in symptoms of memory loss, confusion, and mood changes that can be devastating not only for those affected but also the loved ones around them. In some cases, dementia can also lead to altered personality and hallucinations.
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Signs Of Dementia
No-one at that time could have foreseen the former Prime Minister's later mental decline, least of all her daughter Carol.
In her memoir, A Swim-On Part in a Goldfish Bowl, Carol Thatcher told of her mother's "blotting paper brain" that effortlessly absorbed information.
For more than a decade, Baroness Thatcher struggled with the cruel draining away of her mental faculties.
Carol broke the news that her mother had been suffering from dementia in 2008.
She first noticed her mother's memory failing over lunch in 2000, relating in her book how she "almost fell off her chair" with surprise.
As dementia tightened its grip, Lady Thatcher frequently forgot that her husband, Sir Denis, had died.
Baroness Thatcher's descent into dementia was dramatically - and some say, unfairly - depicted in the film The Iron Lady, with Meryl Streep playing the former British Prime Minister.
Meryl Streep in The Iron Lady
In her book, Carol Thatcher describes how the tell-tale signs of dementia slowly began to emerge.
She wrote: "Whereas previously you would never had had to say anything to her twice, because she'd already filed it away in her formidable memory bank, Mum started asking the same questions over and over again, unaware she was doing so."
After Sir Denis died from cancer in 2003, her mother continually had to be reminded that her husband had gone.
"I had to keep giving the bad news over and over again," said Carol Thatcher. "Every time it finally sank in that she had lost her husband of more than 50 years, she'd look at me sadly and say 'oh', as I struggled to compose myself."
On bad days her mother could "hardly remember the beginning of a sentence by the time she got to the end," Carol recalled.
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How To Talk About Memory Loss
Lady Thatcher became patron of Alzheimer's Research UK, Britain's leading charity dedicated to dementia research, in 2001.
Rebecca Wood, the charity's chief executive, said today: "The loss of Baroness Thatcher will resonate across the world, but in particular with the 820,000 people living with dementia in the UK. Irrespective of personal politics, few would dispute Lady Thatcher's profound influence, the power of her presentation and strength of her convictions.
"That dementia could affect such a forceful personality is a lesson that this cruel condition does not discriminate. As patron to Alzheimer's Research UK, her support of our research could not have been more important, helping draw attention to a condition so frequently swept under the carpet.
"Thanks to Lady Thatcher, we have made inroads with our research to defeat dementia. The answers will come too late for her, but they will come, and this will be another important part of our collective memory of her life and work."
Andrew Chidgey, from the Alzheimer's Society charity which supports dementia sufferers, said:
"Today, up and down the country people will be sharing memories of Baroness Thatcher. At this time we hope people will also reflect on the impact dementia can have on a person's life.
"By speaking openly about the effects of the condition, we will begin to tackle some of the stigma that still surrounds dementia and ensure that everyone gets the support they deserve."