Clinical, Imaging, and Pathologic Characteristics of Patients With Right vs Left Hemisphere-Predominant Logopenic Progressive Aphasia.

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 [F]-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 ( = 0.04) and less frequent phonologic errors ( = 0.015). Patients with rLPA had shorter survival compared to typical LPA: hazard ratio 4.0 (1.2-12.9), = 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.