Affiliations: [a] Department of Neurology, Hospital Clínico Universitario San Carlos, San Carlos Institute for Health Research (IdISSC), Universidad Complutense, Madrid, Spain
| [b] Department of Nuclear Medicine. Hospital Clínico Universitario San Carlos, San Carlos Institute for Health Research (IdISSC), Universidad Complutense, Madrid, Spain
Correspondence:
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Correspondence to: Marta Fernández-Matarrubia, Department of Neurology, Hospital Clínico Universitario San Carlos, C/Profesor Martín Lagos s/n, 28040 Madrid, Spain. Tel.: +34 680183151; Fax: +34 913303512; E-mail: martafmatarrubia@gmail.com.
Abstract: Background: Episodic memory disturbance is still considered as an exclusion criterion for behavioral variant frontotemporal dementia (bvFTD), but growing evidence suggests that memory can be impaired. Objective: Our main purposes were to assess episodic memory in a group of bvFTD patients comparatively with Alzheimer’s disease (AD) patients, and analyze the relationship between episodic memory and brain metabolism measured using positron emission tomography imaging with 18F-fluorodeoxyglucose (FDG-PET). Methods: Twenty-six bvFTD, 29 AD, and 24 healthy controls were included. Episodic memory was assessed by the Free and Cued Selective Reminding Test (FCSRT), which controls for effective encoding and measures memory consolidation processing. All participants underwent FDG-PET brain scans to provide data for voxel-based brain mapping analysis. Results: Half of bvFTD patients had a deficit of total, free delayed, and total free delayed recall as severe as AD patients (amnestic-FTD). The other half had FCSRT scores similar to controls (non-amnestic-FTD). Imaging analyses revealed that amnestic-FTD showed bilateral lower metabolism than non-amnestic-FTD in anterior parahippocampal and inferior temporal gyri. Additionally, FCSRT total and total delayed scores were inversely correlated with parahippocampal metabolism in both bvFTD and AD. Besides, bvFTD showed an inverse association among FCSRT and inferior temporal metabolism. Conclusions: Our findings support that bvFTD could present a genuine amnesia affecting storage and consolidation abilities, which involves structures implicated in the Papez circuit, as occurs in AD, and also inferior temporal regions. These results contribute to understanding the mechanisms underpinning memory dysfunction in bvFTD, and may be relevant to further revisions of the current diagnostic criteria.
