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Phenocopy syndrome of behavioral variant frontotemporal dementia: a systematic review

Authors
  • Valente, Elizabeth Sakamoto
  • Caramelli, Paulo
  • Gambogi, Leandro Boson
  • Mariano, Luciano Inácio
  • Guimarães, Henrique Cerqueira
  • Teixeira, Antônio Lúcio
  • de Souza, Leonardo Cruz
Type
Published Article
Journal
Alzheimer's Research & Therapy
Publisher
BioMed Central
Publication Date
Apr 01, 2019
Volume
11
Issue
1
Identifiers
DOI: 10.1186/s13195-019-0483-2
Source
Springer Nature
Keywords
License
Green

Abstract

BackgroundThe phenocopy syndrome of behavioral variant of frontotemporal dementia (phFTD) refers to patients presenting with neuropsychiatric symptoms mimicking the behavioral variant frontotemporal dementia (bvFTD), but lacking frontotemporal atrophy/hypometabolism on neuroimaging and not evolving to dementia during the follow-up. It is important to recognize phFTD for clinical and research purposes.ObjectiveThe aim of this study was to perform a systematic review of the available literature on phFTD taking into account its clinical, cognitive, imaging, genetic, and pathological features.Methods and resultsWe searched for the following terms in two electronic databases (PubMed and Scopus): “frontotemporal dementia and slowly progressive,” “frontotemporal dementia and phenocopy,” “frontotemporal dementia and non-progressive,” “frontotemporal dementia and benign progression,” and “frontotemporal dementia and benign.” We did not include review articles. Papers had to be written in English, French, Portuguese, or Spanish. Overall, 235 studies were retrieved in the initial search. A total of 31 studies composed the final selection, comprising 292 patients. Patients with phFTD are predominantly male and have no major cognitive deficits, with globally preserved executive functions and episodic memory. Some cases (n = 7) of slowly progressive FTD have been associated with C9orf72 genetic expansion. There are only four reports of phFTD neuropathological data, with two patients with no neurodegenerative findings and two with frontotemporal lobar degeneration with ubiquitin-positive inclusions.ConclusionThe neurobiological underpinnings of phFTD remain unknown. It is controversial whether phFTD belongs to the FTD spectrum. Studies with biomarkers and pathological data are needed to solve the phFTD conundrum.

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