Automatically Calculated Context-Sensitive Features of Connected Speech Improve Prediction of Impairment in Alzheimer's Disease
Bibliographic record
Abstract
Purpose: Early detection is critical for effective management of Alzheimer's disease (AD) and other dementias. One promising approach for predicting AD status is to automatically calculate linguistic features from open-ended connected speech. Past work has focused on individual word-level features such as part of speech counts, total word production, and lexical richness, with less emphasis on measuring the relationship between words and the context in which they are produced. Here, we assessed whether linguistic features that take into account where a word was produced in the discourse context improved the ability to predict AD patients' Mini-Mental State Examination (MMSE) scores and classify AD patients from healthy control participants. Method: Seventeen linguistic features were automatically computed from transcriptions of spoken picture descriptions from individuals with probable or possible AD ( n = 176 transcripts). This included 12 word-level features (e.g., part of speech counts) and five features capturing contextual word choices (linguistic surprisal, computed from a computational large language model, and properties of words produced following filled pauses). We examined whether (a) the full set jointly predicted MMSE scores, (b) the addition of contextual features improved prediction, and (c) linguistic features could classify AD patients ( n = 130) versus healthy participants ( n = 93). Results: Linguistic features accurately predicted MMSE scores in individuals with probable or possible AD and successfully identified up to 87% of AD participants versus healthy controls. Statistical models that contained linguistic surprisal (a contextual feature) performed better than those that included only word-level and demographic features. Overall, AD patients with lower MMSE scores produced more empty words, fewer nouns and definite articles, and words that were higher frequency yet more surprising given the previous context. Conclusion: These results provide novel evidence that metrics related to contextualized word choices, particularly the surprisal of an individual's words, capture variance in degree of cognitive decline in AD.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.005 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".