Harold Wilson may have been suffering the early stages of Alzheimer's disease when he stunned Britain by resigning as Prime Minister, new research suggests.
At the time he said he was simply mentally and physically exhausted, prompting an array of conspiracy theories seeking the real reason for his departure days after his 60th birthday in 1976. But analysis of his speech patterns has found that Wilson may have already been suffering the early stages of the disease which went on to destroy his prodigious memory and powers of concentration.
Dr Peter Garrard, Reader in Neurology at the University of Southampton School of Medicine, reports he has found a decline in mental function in Wilson's final months in Downing Street. He concludes that the onset of the disease could have contributed to Wilson's shock decision to step down as Prime Minister and Labour leader.
Dr Garrard has previously uncovered linguistic changes in the later writings of the novelist Iris Murdoch which pointed to the effects of Alzheimer's. In this new study, he examined Wilson's performances at the Commons dispatch box in the cut-and-thrust of parliamentary debate during his two spells as Prime Minister, in 1964-70 and 1974-76.
His research suggests that during his final months in office Wilson was losing his distinctive voice – seen as an indication the disease was beginning to have an impact on his speech patterns.
Dr Garrard's analysis, published yesterday in the Journal of Neurolinguistics, was based on linguistic techniques used by academics to investigate literary trends and develop theories on the true authors of disputed works.
He said: "Language is known to be vulnerable to the earliest stages of Alzheimer's disease, and the findings of the earlier Iris Murdoch project confirmed that linguistic changes can appear even before the symptoms are recognised by either the patient or their closest associates.
"If such changes are apparent during the effortful and relatively controlled process of creative writing, then the cognitive demands of spontaneous speech production make it even more likely for them to be detectable in spoken output." Wilson's health declined rapidly after his resignation and he was seen less in public. He died of cancer in 1995, aged 79, and was buried in the Isles of Scilly. Wilson won four of the five elections he fought as Labour leader – more than any other Prime Minister of the 20th century. He spent nearly eight years as Prime Minister and another five as leader of the Opposition.
Rebecca Wood, of the Alzheimer's Research Trust, said: "That such a politician, despite his hectic schedule and renowned intellect, could develop Alzheimer's suggests no one is immune. Margaret Thatcher developed dementia after leaving office, and many historians believe Ronald Reagan's Alzheimer's was already present during his second term.
"Both figures had an enormous impact on public awareness of a condition too often swept under the carpet."
Alzheimer's: The facts
*Alzheimer's disease, which affects more than 400,000 Britons, is the most common type of dementia. As it develops, the structure of the brain is attacked and the transmission of messages between different parts of the brain is impaired by a shortage of the right chemicals. In the early stages, sufferers tend to have trouble remembering things and will often spend time searching for words. They may start substituting unusual or incorrect words for ones they have forgotten, or even invent new ones of their own. As the disease progresses, this forgetfulness becomes ever more severe and can lead to extreme confusion. Consequently, people with the illness tend to become withdrawn as they lose their confidence in their ability to act normally. They often experience mood swings, feeling sad or angry about their inability to express themselves in their usual way.