When words first fail: Predicting the emergence of primary progressive aphasia variants from unclassifiable anomic performance in early disease

ABSTRACT

Background

The majority of patients with primary progressive aphasia (PPA) can be distinguished into one of three variants: semantic, non-fluent/agrammatic, or logopenic. However, many do not meet criteria for any one variant.

Aim

To identify aspects of cognitive-linguistic performance that yield an early unclassifiable PPA designation that predicted the later emergence of a given variant.

Methods & Procedures

Of 256 individuals with PPA evaluated, 19 initially were unclassifiable and later met criteria for a variant. Receiver operating characteristic curves were used to evaluate the binary ability of a given task to predict eventual classification as a given variant. Tasks with a high area under the curve were examined using regression analyses to determine their ability to predict variant.

Outcomes & Results

High mean predictive value was observed for multiple naming assessments targeting nouns and verbs. The Boston Naming Test (BNT) was the only test that, in isolation, resulted in a significant model and high classification accuracy.

Conclusions

Although naming impairment is common across PPA variants, very low initial BNT scores emerged as a uniquely accurate basis for predicting eventual semantic variant, and normal BNT scores predicted eventual nonfluent/agrammatic variant. High performance on picture-verb verification was useful in identifying future lvPPA.

KEYWORDS:

• dementia
• primary progressive aphasia
• evaluation

Author Contributions

MDS & AEH designed the study. All authors contributed to data acquisition. DCT, BLB, & MDS aggregated the data for analysis. MDS completed the analysis, then drafted the manuscript. All authors provided insight into interpretation of the results and read and revised the manuscript for clarity.

Disclosure Statement

The authors report there are no competing interests to declare.

Data Availability Statement

Data are available upon reasonable request from the authors.

This work is supported by National Institutes of Health/National Institute on Deafness and Other Communication Disorders (NIH/NIDCD): R01 DC011317 and P50 DC014664.

Additional information

Funding

This work was supported by the the National Institute on Deafness and Other Communication Disorders [P50 DC014664, R01 DC011317].