OBJECTIVE: We aimed to examine if single photon emission computed tomography (SPECT) can discriminate between variants of frontotemporal dementia (FTD). As a secondary investigation we identify and establish the linguistic differences between those variants.
MATERIALS AND METHODS: Nine patients with semantic variant primary progressive aphasia (svPPA), 8 with non-fluent variant primary progressive aphasia (nfvPPA) and 17 with behavioral variant of frontotemporal dementia (bvFTD) were compared on Addenbrooke's cognitive examination-revised (ACE-R), auditory comprehension, oral expression and verbal fluency. All patients were also compared with healthy controls. Patients were evaluated using technetium-99m-hexamethylproyleneamine oxime (Tc-HMPAO) brain SPECT as a measure of regional cerebral flow.
RESULTS: Significant group differences between all patients and controls were found for ACE-R, auditory comprehension and oral expression. Semantic variant primary progressive aphasia patients performed higher in letter compared to category fluency with significant deficits in auditory comprehension and oral expression. Non-fluent variant primary progressive aphasia patients showed significant deficits in auditory comprehension but not oral expression while performed lightly worse in letter fluency compared to category. Behavioral variant of frontotemporal dementia patients showed deficits in auditory comprehension and oral expression and performed similar in category and letter fluency. Single photon emission computed tomography analysis revealed left frontotemporal hypoperfusion extending to the right frontotemporal region in svPPA patients. Non-fluent variant primary progressive aphasia patients presented left frontotemporal hypoperfusion with participation of the left parietal and right frontotemporal regions. Behavioral variant of frontotemporal dementia patients showed bilateral frontotemporal hypoperfusion compared to parietal and visual cortices.
CONCLUSION: Our findings suggest that SPECT may assist in the discrimination of the FTD variants. We also confirmed that bvFTD patients share similar language deficits with svPPA patients.