Slowed articulation rate is a sensitive diagnostic marker for identifying non-fluent primary progressive aphasia.
Claire Cordella, Bradford C Dickerson, Megan Quimby and 2 others
PMID 28757671WHAT IT FOUND
The rate measures did not clearly beat clinician fluency ratings in the main accuracy comparison, but slow articulation rate was the best marker and helped identify non-fluent PPA when false alarms were low.
Key findings
01Slow articulation rate separated non-fluent PPA from logopenic PPA, semantic PPA and healthy controls.
02In this sample, articulation rate identified non-fluent PPA versus logopenic PPA with 92% accuracy, 82% sensitivity and 100% specificity.
03The main accuracy comparison did not show a significant difference between rate measures and clinician fluency ratings, but articulation rate was significantly better when few false positives were allowed.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
Only 38 people with primary progressive aphasia and 8 healthy controls were studied, so accuracy numbers may not apply to other clinics. The paper describes clinical consensus diagnosis, not pathology or imaging confirmation. The study did not include people with other motor speech disorders or other dementia types, so it does not show that slow articulation rate distinguishes non-fluent PPA from all similar conditions. No logopenic or semantic PPA participants were judged to have apraxia or dysarthria, so the subtype groups may be cleaner than typical clinic cases. When several speech samples were available for one person, only the first was used, so the study does not show how articulation rate changes over time. The small sample may explain why the main accuracy comparison did not reach significance even though restricted false-positive analysis favoured articulation rate.
The easy way to misread this
Do not treat articulation rate as a validated stand-alone diagnostic test. The study had 38 people with primary progressive aphasia and 8 controls, and the main accuracy difference from clinician ratings did not reach significance.