Open AccessNeurobehavioral Characteristics of FDG-PET Defined Right-Dominant Semantic Dementia: A Longitudinal Study
Author(s) -
Alexis X. Curet Burleson,
Nha Trang Thu Pham,
Marina Buciuc,
Hugo Botha,
Heather M. Clark,
Rene L. Utianski,
Mary M. Machulda,
Matthew Baker,
Rosa Rademakers,
Val J. Lowe,
Jennifer L. Whitwell,
Keith A. Josephs
Publication year - 2021
Publication title -
dementia and geriatric cognitive disorders
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.026
H-Index - 110
eISSN - 1421-9824
pISSN - 1420-8008
DOI - 10.1159/000513979
Subject(s) - disinhibition , psychology , temporal lobe , medicine , dementia , audiology , cardiology , nuclear medicine , neuroscience , disease , epilepsy
Semantic dementia (SD) is characterized by fluent speech, anomia, and loss of word and object knowledge with varying degrees of right and left anterior-medial temporal lobe hypometabolism on [ 18 F] fluorodeoxyglucose (FDG)-PET. We assessed neurobehavioral features in SD patients across 3 FDG-PET-defined metabolic patterns and investigated progression over time. Methods: Thirty-four patients with SD who completed FDG-PET were classified into a left- and right-dominant group based on the degree of hypometabolism in each temporal lobe. The left-dominant group was further subdivided depending on whether hypometabolism in the right temporal lobe was more or less than 2 standard deviations from controls (left+ group). Neurobehavioral characteristics determined using the Neuropsychiatric Inventory Questionnaire (NPI-Q) were compared across groups. Progression of NPI-Q scores and FDG-PET hypometabolism was assessed in 14 patients with longitudinal follow-up. Results: The right-dominant group performed worse on the NPI-Q and had a greater frequency of abnormal behaviors and more severe disinhibition compared to the left-dominant group. Performance on the NPI-Q and severity of disinhibition correlated with right medial and lateral, but not left, temporal lobe hypometabolism. Severity of abnormal behaviors worsened over time in most left-dominant and left+ patients but appeared to improve in the 2 right-dominant patients with longitudinal follow-up. All groups showed progressive worsening of metabolism in both temporal lobes over time, with hypometabolism spreading from anteromedial to posterior temporal regions. However, the degree of temporal lobe asymmetry remained relatively constant over time. Conclusion: In SD, neurobehavioral features, especially disinhibition, are associated with right medial and lateral temporal lobe hypometabolism and commonly develop over time even in patients that present with left-dominant patterns of hypometabolism.