New study suggests Terry Pratchett’s novels may have held clues to his dementia a decade before diagnosis | Detecting Dementia Using Lexical Analysis: Terry Pratchett’s Discworld Tells a More Personal Story

Some parts of the write-up:

>Dementia is often described as a condition of memory loss, but this is only part of the story. In its earliest stages, dementia can affect attention, perception and language before memory problems become obvious. These early changes are difficult to detect because they are gradual and easily mistaken for stress, ageing or normal variation in behaviour.
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>Language, however, offers a unique window into cognitive change. The words we choose, the variety of our vocabulary and the way we structure description are tightly linked to brain function. Even small shifts in language use may reflect underlying neurological change.
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>In our recent study, we analysed the language used across Terry Pratchett’s Discworld novels, examining how his writing evolved over time. We focused on “lexical diversity” — a measure of how varied an author’s word choices are — and paid particular attention to adjectives, the descriptive words that give prose its texture, colour and emotional depth.
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>Across Pratchett’s later novels, there was a clear and statistically significant decline in the diversity of adjectives he used. The richness of descriptive language gradually narrowed. This was not something a reader would necessarily notice, nor did it reflect a sudden deterioration in quality. Instead, it was a subtle, progressive change detectable only through detailed linguistic analysis.
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>Crucially, the first significant drop appeared in The Last Continent, published almost ten years before Pratchett received his formal diagnosis. This suggests that the “preclinical phase” of dementia — the period during which disease-related changes are already occurring in the brain — may have begun many years earlier, without obvious outward symptoms.
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>This finding has implications that extend far beyond literary analysis. Dementia is known to have a long preclinical phase, during which opportunities for early intervention are greatest. Yet identifying people during this window remains one of the biggest challenges in dementia care.
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>…
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>Early detection matters more than ever. In recent years, new drugs for Alzheimer’s disease have emerged that aim to slow disease progression rather than simply manage symptoms. Drugs such as lecanemab and donanemab target amyloid proteins that accumulate in the brain and are thought to play an important role in the disease. Clinical trials suggest these treatments would be most effective when given early, before significant neuronal damage has occurred.

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Research link: [Detecting Dementia Using Lexical Analysis: Terry Pratchett’s Discworld Tells a More Personal Story](https://www.mdpi.com/2076-3425/16/1/94)

Abstract:

>**Background/Objectives**: Dementia, characterised by cognitive decline, significantly impacts language abilities. While the risk of dementia increases with age, it often manifests years before clinical diagnosis. Identifying early warning signs is crucial for timely intervention. Previous research has demonstrated that changes in language, such as reduced vocabulary diversity and simpler sentence structures, may be observed in individuals with dementia. This study investigates the potential of linguistic analysis to detect early signs of cognitive decline by examining the writing of Sir Terry Pratchett, a renowned author diagnosed with Posterior Cortical Atrophy (PCA), typically a form of dementia caused by Alzheimer’s disease.
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>**Methods**: This study analysed 33 Discworld novels by Terry Pratchett, comparing linguistic features before and after a potential turning point identified through analysis of adjective type-token ratios (TTR).
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>**Results**: A significant decrease in lexical diversity (TTR) was observed for nouns and adjectives in later works. Total wordcount increased, while lexical diversity decreased, suggesting a shift towards simpler language. This shift coincided with a decrease in adjective TTR below a defined threshold, occurring approximately ten years before Pratchett’s formal diagnosis.
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>**Conclusions**: These findings suggest that subtle changes in linguistic patterns, such as decreased lexical diversity, may precede clinical diagnosis of dementia by a considerable margin. This research highlights the potential of linguistic analysis as a valuable tool for early detection of cognitive decline. Further research is needed to validate these findings in larger cohorts and explore the specific linguistic markers associated with different types of dementia.

I believe they’ve studied Agatha Christie books and made the same determination.

So a sample size of one.

It’s an interesting insight into dementia, but the truth is whenever I feel the need to read a book for joy, I read a Terry Pratchett story.

I’ve read a lot of Terry Pratchett, but haven’t yet read his later Discworld books. I’ve heard that they do kind of go off the rails in terms of quality and that he was basically dictating them from his bed. It’ll be interesting to see the difference.

Need to compare to similar authors who did not develop dementia. Pratchett may have been getting more efficient, changing style, bored with writing etc. Or not, but without embedding in broader writing community is suggestive rather than revealing

That’s gross and morbid 

ChatGPT users right now:

“do a lexical analysis on all of our chats and see if I have dementia”

I don’t know about writers, but painters often develop an ‘old’ mature style. Which is where they, to put it crudely, relinquish detail in their paintings. They develop a loose and brushy style. Something that might be seen as becoming more and more expert – more efficient. Good examples would be Rembrandt and Picasso. Whose late works exemplify this. I’ve never considered that this might be similar in professional writing before? A maturing writer may actually appear to be developing dementia, when in fact they’re just maturing?

Willem De Kooning did actually develop dementia, and his late paintings do progressively become simpler and simpler. It’s possible somebody was eventually just sticking a paintbrush in his hand?