Frontal variant of Alzheimer’s disease masquerading as behavioural-variant frontotemporal dementia: a case study comparison

ABSTRACT

The current clinical diagnostic criteria for Alzheimer’s disease (AD) recognize an atypical, non-amnestic presentation of AD, characterized by prominent executive dysfunction. Increasing evidence, however, indicates that the clinical phenotype of this so-called “frontal-variant” of AD (fv-AD) includes behavioral symptoms and deficits in social cognition, together with disproportionate frontal lobe atrophy. As these features resemble those characteristic of behavioral-variant frontotemporal dementia (bvFTD), differential diagnosis can be challenging. Here, we report a case of fv-AD who met clinical diagnostic criteria bvFTD, but had in vivo amyloid neuroimaging evidence of AD pathology. We compare this case against two individuals who were clinically diagnosed with bvFTD and early-onset AD, with in vivo amyloid neuroimaging confirmation of pathology. We highlight the challenges in differential diagnosis by contrasting their behavioral, cognitive and structural neuroimaging findings.

KEYWORDS:

• Alzheimer’s disease
• behavioural-variant frontotemporal dementia
• episodic memory
• executive function
• social cognition

Acknowledgments

The authors are grateful to the participants and their families for supporting our research. The authors are also grateful to Professor Christopher Rowe and Associate Professor Victor Villemagne for conducting the amyloid neuroimaging procedures at Austin Hospital, Melbourne.

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

This work was supported in part by funding to ForeFront, a collaborative research group dedicated to the study of frontotemporal dementia and motor neuron disease, from the National Health and Medical Research Council (NHMRC) (APP1037746) and the Australian Research Council (ARC) Centre of Excellence in Cognition and its Disorders Memory Program (CE11000102). In addition, this study was supported by NHMRC Project Grant (APP1121791). OP is an NHMRC Senior Research Fellow (APP1103258). FK is supported by an NHMRC-ARC Dementia Research Development Fellowship (APP1097026) .