title: False Recognition in Behavioral Variant Frontotemporal Dementia and Alzheimer's Disease-Disinhibition or Amnesia?
abstract: Episodic memory recall processes in Alzheimer's disease (AD) and behavioral variant frontotemporal dementia (bvFTD) can be similarly impaired, whereas recognition performance is more variable. A potential reason for this variability could be false-positive errors made on recognition trials and whether these errors are due to amnesia per se or a general over-endorsement of recognition items regardless of memory. The current study addressed this issue by analysing recognition performance on the Rey Auditory Verbal Learning Test (RAVLT) in 39 bvFTD, 77 AD and 61 control participants from two centers (India, Australia), as well as disinhibition assessed using the Hayling test. Whereas both AD and bvFTD patients were comparably impaired on delayed recall, bvFTD patients showed intact recognition performance in terms of the number of correct hits. However, both patient groups endorsed significantly more false-positives than controls, and bvFTD and AD patients scored equally poorly on a sensitivity index (correct hits-false-positives). Furthermore, measures of disinhibition were significantly associated with false positives in both groups, with a stronger relationship with false-positives in bvFTD. Voxel-based morphometry analyses revealed similar neural correlates of false positive endorsement across bvFTD and AD, with both patient groups showing involvement of prefrontal and Papez circuitry regions, such as medial temporal and thalamic regions, and a DTI analysis detected an emerging but non-significant trend between false positives and decreased fornix integrity in bvFTD only. These findings suggest that false-positive errors on recognition tests relate to similar mechanisms in bvFTD and AD, reflecting deficits in episodic memory processes and disinhibition. These findings highlight that current memory tests are not sufficient to accurately distinguish between bvFTD and AD patients.
authors.affiliation: Neuroscience Research AustraliaSydney, NSW, Australia; Department of Clinical Neurosciences, University of CambridgeCambridge, UK; Norwich Medical School, University of East AngliaNorwich, UK.
authors.forename: Emma C
authors.initials: EC
authors.lastname: Flanagan
authors.affiliation: Neuroscience Research AustraliaSydney, NSW, Australia; Australian Research Council Centre of Excellence in Cognition and its DisordersSydney, NSW, Australia.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Wong
authors.affiliation: Department of Neurology and Cognitive Neurology Unit, Apollo Gleneagles Hospital Kolkata, India.
authors.forename: Aparna
authors.initials: A
authors.lastname: Dutt
authors.affiliation: Neuroscience Research Australia Sydney, NSW, Australia.
authors.forename: Sicong
authors.initials: S
authors.lastname: Tu
authors.affiliation: Department of Clinical Neurosciences, University of CambridgeCambridge, UK; Norwich Medical School, University of East AngliaNorwich, UK.
authors.forename: Maxime
authors.initials: M
authors.lastname: Bertoux
authors.affiliation: Neuroscience Research AustraliaSydney, NSW, Australia; Australian Research Council Centre of Excellence in Cognition and its DisordersSydney, NSW, Australia; School of Psychology, University of New South WalesSydney, NSW, Australia.
authors.forename: Muireann
authors.initials: M
authors.lastname: Irish
authors.affiliation: Neuroscience Research AustraliaSydney, NSW, Australia; Australian Research Council Centre of Excellence in Cognition and its DisordersSydney, NSW, Australia; School of Medical Sciences, University of New South WalesSydney, NSW, Australia.
authors.forename: Olivier
authors.initials: O
authors.lastname: Piguet
authors.affiliation: Department of Neurology and Cognitive Neurology Unit, Apollo Gleneagles Hospital Kolkata, India.
authors.forename: Sulakshana
authors.initials: S
authors.lastname: Rao
authors.affiliation: Neuroscience Research AustraliaSydney, NSW, Australia; Australian Research Council Centre of Excellence in Cognition and its DisordersSydney, NSW, Australia; School of Medical Sciences, University of New South WalesSydney, NSW, Australia.
authors.forename: John R
authors.initials: JR
authors.lastname: Hodges
authors.affiliation: Department of Neurology and Cognitive Neurology Unit, Apollo Gleneagles Hospital Kolkata, India.
authors.forename: Amitabha
authors.initials: A
authors.lastname: Ghosh
authors.affiliation: Norwich Medical School, University of East AngliaNorwich, UK; Australian Research Council Centre of Excellence in Cognition and its DisordersSydney, NSW, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Hornberger
keywords: Alzheimer's disease; disinhibition; frontotemporal dementia; memory; recognition