Objective: This study aimed to assess the diagnostic contribution of
Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) in
neurodegenerative dementias presenting with language-predominant
symptoms, with or without accompanying behavioral changes, and to
evaluate the correspondence between PET-derived metabolic patterns
and cerebrospinal fluid (CSF) biomarkers.
Methods: Sixteen patients with language-predominant onset were
categorized into two groups: Alzheimer’s disease (AD) spectrum (n=8)
and the frontotemporal lobar degeneration (FTLD) spectrum (n=8). All
participants underwent clinical evaluation, neuropsychological testing,
and FDG-PET imaging. Cerebrospinal fluid biomarkers [Amyloid Beta
(Aβ42), total tau, and phosphorylated tau] were analyzed in eligible
individuals (n=6). The two groups were compared across demographic,
clinical, and neuroimaging parameters.
Results: FDG-PET revealed pronounced posterior temporoparietal
hypometabolism in AD-spectrum patients, whereas FTLD-spectrum
patients demonstrated frontal, insular, and anterior temporal metabolic
involvement. Cerebrospinal fluid biomarker profiles consistently
supported Alzheimer-type pathology among AD-spectrum cases. In the
FTLD group, one patient exhibited borderline-low Aβ42; however, the
corresponding FDG-PET pattern was characteristic of FTLD.
Conclusion: FDG-PET demonstrates a supportive role in differentiating
AD from FTLD among patients presenting with language-predominant
neurodegenerative syndromes. In scenarios where CSF biomarkers are
unavailable or yield borderline values, FDG-PET-based metabolic
signatures may offer additional guidance and can contribute to
strengthening multimodal diagnostic frameworks in geropsychiatry
settings.
Keywords: Alzheimer’s Disease, biomarker, dementia, FDG-PET,
frontotemporal dementia, imaging, language impairment