“More than words” – Longitudinal linguistic changes in the works of a writer diagnosed with semantic dementia

ABSTRACT

Leveraging recent advances in automated language analysis and anovel statistical approach utilizing an independent control group, we explored changes in lexical output across two published works of a man diagnosed with semantic dementia. We found significant increase in adverb usage and decline in familiarity, meaningfulness, age of acquisition and co-occurrence probability over 2 years. Collectively, these indices suggest that WR’s narrative structure became progressively simpler, lexically less sophisticated, and that words commonly associated together no longer appeared in close proximity. Our study illustrates how degeneration of the semantic knowledge base impacts the production, content, and quality of literary works.

KEYWORDS:

• Primary progressive aphasia
• semantic dementia
• language
• psycholinguistic profile
• lexical analysis

Abbreviations

ACE-IIIAddenbrooke’s cognitive examination third edition

ATLAnterior temporal lobe

BNCBritish national corpus

CCVControl corpus variability

FTD-FRSFrontotemporal dementia functional rating scale

MRCMedical Research Council

RCFRay complex figure

ROIRegion of interest

st.devStandard deviation

SYDBATSydney Language Battery Test

TAACOTool for the automatic analysis of cohesion

TAALESTool for the automatic analysis of lexical sophistication

TMTTrail making test

Acknowledgments

The authors would like to thank WR for his participation in our research and sharing his original manuscripts for this project. The authors acknowledge the technical assistance of Jim Matthews of the Sydney Informatics Hub, a Core Research Facility of the University of Sydney. The authors would also like to thank Dr Cristian Leyton Moscoso for his comments on the manuscript.

Disclosure statement

The authors report no competing interests.

Notes

1. Under the Net (published in 1954), The Sea, The Sea (1978) and Jackson’s Dilemma (1995).

2. WR’s spouse advised that there were occasions when WR would ask for an alternate word, or suggestions on phrasing. However, these occurrences were not frequent, and while she was not keeping an event diary, she did not feel that the frequency of these occurrences were noticeably different between the two books. We propose that these occurrences are not outside the boundaries of the “normal” writing process.

Additional information

Funding

This work was supported in part by funding to ForeFront, a collaborative research group dedicated to the study of frontotemporal dementia and motor neuron disease, from the National Health and Medical Research Council (NHMRC) (GNT1037746) and the Australian Research Council (ARC) Centre of Excellence in Cognition and its Disorders Memory Program (CE11000102). OP is supported by an NHMRC Senior Research Fellowship (GNT1103258). MI is supported by an ARC Future Fellowship (FT160100096).