The Diagnostic Patterns of Referring Physicians and Hospital Expert Psychiatrists Regarding Particular Frontotemporal Lobar Degeneration Clinical and Neuropathological Subtypes

Background: It is important to make accurate clinical diagnosis of frontotemporal lobar degeneration (FTLD), which in turn, leads to future therapic approaches. The FTLD cases are frequently inaccurately identified, but the frequency of this misidentification according to the underlying pathological subtypes is still unclear. Objective: We aimed to quantify the accuracy of behavioral variant frontotemporal dementia (bvFTD) and semantic variant primary progressive aphasia (svPPA) diagnoses by both the patients' referring physicians and hospital expert psychiatrists, and we investigated whether the physicians' and psychiatrists' diagnostic patterns are associated with a specific neuropathology. Methods: We retrospectively analyzed the cases of a series of Japanese patients with pathologically diagnosed FTLD (n = 55): the bvFTD group (n = 47) consisted of patients with FTLD-tau (n = 20), FTLD-TDP (TAR DNA-binding protein of 43-kDA) (n = 19), and FTLD-FUS (fused in sarcoma) (n = 8). The svPPA patients (n = 8) all had FTLD-TDP. Results: Only31% of the patients' referring physicians mentionedFTDsyndrome. The referring psychiatrists and neurologists showed similar diagnostic accuracy. High diagnostic accuracy was observed for the TDP pathology group (mainly svPPA patients). The FTLD-FUS patients were more likely to be diagnosed as having a psychiatric disorder by referring physicians. The hospital expert psychiatrists' accuracy for identifying FTLD-tau pathology was low. Conclusion: The results of our analyses revealed a specific diagnostic pattern associated with particular FTLD pathological subtypes, which will help to improve non-specialists' diagnostic ability.