Led by Loughborough University’s Dr Thom Wilcockson, researchers examined the "lexical diversity" – a measure of how varied an author’s word choices are – of 33 books from Pratchett's Discworld series, focusing specifically on his use of nouns and adjectives.
The study found that Pratchett’s language in “The Lost Continent”, written almost 10 years before his diagnosis of Posterior Cortical Atrophy (PCA), a rare form of Alzheimer's, showed a significant decline in the complexity of the language used compared to his previous works.
Published in peer-reviewed journal Brain Sciences, the research team hope that the study may aid in the early detection of dementia, for which there is currently no cure.
Dr Thom Wilcockson, from Loughborough’s School of Sport, Exercise and Health Sciences, explained: “Identifying dementia in the early stages is important as it may enable us to use interventions sooner before the brain is damaged beyond repair.
“Research indicates that memory problems may not be the first symptom of dementia. We wanted to explore whether language could be an early warning sign, and to do this, we used Sir Terry Pratchett’s books, who himself suffered dementia.
“Our analysis found that Sir Terry’s use of language did indeed change during his career. These results suggest that language may be one of the first signs of dementia, and Sir Terry’s books reveal a potential new approach for early diagnosis.”
Supporting researcher, Dr Melody Pattison, Lecturer in the School of English, Communication and Philosophy, Cardiff University, added: "We would normally expect less lexical diversity as texts get longer, but even after controlling for text length, our findings were still significant. The shifts in language were not something a reader would necessarily notice, but rather a subtle, progressive change.”
Sir Terry Pratchett spoke candidly about the disease and was vocal that more needed to be done to raise awareness. He sadly died in 2015, aged 66.