Affiliations: [a] ARC Centre of Excellence in Cognition and its Disorders, Sydney, Australia | [b] Department of Psychology, Macquarie University, Sydney, Australia | [c] Neuroscience Research Australia, Sydney, Australia | [d] Department of Clinical Neurosciences, Cambridge University, UK | [e] School of Medical Sciences, the University of New South Wales, Sydney, Australia | [f] Norwich Medical School, University of East Anglia, UK
Correspondence:
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Correspondence to: Michael Hornberger, Norwich Medical School, University of East Anglia, NR4 7TJ, Norwich, UK. Tel.: +44 1603 593540; Fax: +44 1603 593752; E-mail: m.hornberger@ uea.ac.uk.
Abstract: Alzheimer’s disease (AD) sometimes presents with prominent executive dysfunction and associated prefrontal cortex atrophy. The impact of such executive deficits on episodic memory performance as well as their neural correlates in AD, however, remains unclear. The aim of the current study was to investigate episodic memory and brain atrophy in AD patients with relatively spared executive functioning (SEF-AD; n = 12) and AD patients with relatively impaired executive functioning (IEF-AD; n = 23). We also compared the AD subgroups with a group of behavioral-variant frontotemporal dementia patients (bvFTD; n = 22), who typically exhibit significant executive deficits, and age-matched healthy controls (n = 38). On cognitive testing, the three patient groups showed comparable memory profiles on standard episodic memory tests, with significant impairment relative to controls. Voxel-based morphometry analyses revealed extensive prefrontal and medial temporal lobe atrophy in IEF-AD and bvFTD, whereas this was limited to the middle frontal gyrus and hippocampus in SEF-AD. Moreover, the additional prefrontal atrophy in IEF-AD and bvFTD correlated with memory performance, whereas this was not the case for SEF-AD. These findings indicate that IEF-AD patients show prefrontal atrophy in regions similar to bvFTD, and suggest that this contributes to episodic memory performance. This has implications for the differential diagnosis of bvFTD and subtypes of AD.
Keywords: Dementia, needs assessment, primary health care, randomized controlled trial
