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Abstract
Objective To assess and compare demographic, clinical, neuroimaging, and pathologic characteristics of a cohort of patients with right hemisphere–predominant vs left hemisphere–predominant logopenic progressive aphasia (LPA).
Methods This is a case-control study of patients with LPA who were prospectively followed at Mayo Clinic and underwent [18F]-fluorodeoxyglucose (FDG) PET scan. Patients were classified as rLPA if right temporal lobe metabolism was ≥1 SD lower than left temporal lobe metabolism. Patients with rLPA were frequency-matched 3:1 to typical left-predominant LPA based on degree of asymmetry and severity of temporal lobe metabolism. Patients were compared on clinical, imaging (MRI, FDG-PET, β-amyloid, and tau-PET), and pathologic characteristics.
Results Of 103 prospectively recruited patients with LPA, 8 (4 female) were classified as rLPA (7.8%); all patients with rLPA were right-handed. Patients with rLPA had milder aphasia based on the Western Aphasia Battery–Aphasia Quotient (p = 0.04) and less frequent phonologic errors (p = 0.015). Patients with rLPA had shorter survival compared to typical LPA: hazard ratio 4.0 (1.2–12.9), p = 0.02. There were no other differences in demographics, handedness, genetics, or neurologic or neuropsychological tests. Compared to the 24 frequency-matched patients with typical LPA, patients with rLPA showed greater frontotemporal hypometabolism of the nondominant hemisphere on FDG-PET and less atrophy in amygdala and hippocampus of the dominant hemisphere. Autopsy evaluation revealed a similar distribution of pathologic findings in both groups, with Alzheimer disease pathologic changes being the most frequent pathology.
Conclusions rLPA is associated with less severe aphasia but has shorter survival from reported symptom onset than typical LPA, possibly related to greater involvement of the nondominant hemisphere.
Glossary
- Aβ=
- β-amyloid;
- AD=
- Alzheimer disease;
- AES=
- articulatory errors score;
- AQ=
- Aphasia Quotient;
- AVLT=
- Auditory Verbal Learning Test;
- BDAE=
- Boston Diagnostic Aphasia Examination;
- CAD=
- crossed aphasia in dextrals;
- CI=
- confidence interval;
- FBI=
- Frontal Behavioral Inventory;
- FDG=
- fluorodeoxyglucose;
- HR=
- hazard ratio;
- LPA=
- logopenic progressive aphasia;
- MCALT=
- Mayo Clinic Adult Lifespan Template;
- MoCA=
- Montreal Cognitive Assessment;
- MPRAGE=
- magnetization-prepared rapid-acquisition gradient-echo;
- NRG=
- Neurodegenerative Research Group;
- PiB=
- Pittsburgh compound B;
- PPA=
- primary progressive aphasia;
- PVC=
- partial volume correction;
- rLPA=
- right hemisphere–predominant logopenic progressive aphasia;
- SUVR=
- standard uptake value ratio;
- TDP-43=
- trans-active response DNA-binding protein 43 kDa;
- WAB=
- Western Aphasia Battery
Footnotes
Go to Neurology.org/N for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
- Received November 18, 2020.
- Accepted in final form April 27, 2021.
- © 2021 American Academy of Neurology
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