Severity assessment scales for frontotemporal lobar degeneration (FTLD) have been recently introduced. In the present study, the authors examined whether the FTLD-modified Clinical Dementia Rating (FTLD-CDR) scale and the Frontotemporal Dementia Rating Scale (FRS) correlated with regional brain perfusion in Greek FTLD patients. A total of 47 behavioral variant frontotemporal dementia (bvFTD) patients and 33 primary progressive aphasia (PPA) patients were assessed for demographic data, cognitive reserve (CR), and severity of dementia and underwent brain single-photon emission computed tomography. Both scales were valid in the bvFTD group, predicting frontal lobe perfusion. In the PPA group, both scales were found to predict temporal hypoperfusion only after accounting for CR, which could imply a potential role for reserve in PPA patients.