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Cortex. 2015 Jun;67:83-94. doi: 10.1016/j.cortex.2015.03.016. Epub 2015 Apr 2.

Lost in spatial translation - A novel tool to objectively assess spatial disorientation in Alzheimer's disease and frontotemporal dementia.

Author information

1
Neuroscience Research Australia, Randwick, Sydney, Australia; Australian Research Council Centre of Excellence in Cognition and its Disorders, Sydney, Australia; School of Medical Sciences, University of New South Wales, Sydney, Australia.
2
Neuroscience Research Australia, Randwick, Sydney, Australia; Australian Research Council Centre of Excellence in Cognition and its Disorders, Sydney, Australia; School of Psychology, University of New South Wales, Sydney, Australia.
3
Australian Research Council Centre of Excellence in Cognition and its Disorders, Sydney, Australia; School of Medical Sciences, University of New South Wales, Sydney, Australia; Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom. Electronic address: mh486@medschl.cam.ac.uk.

Abstract

Spatial disorientation is a prominent feature of early Alzheimer's disease (AD) attributed to degeneration of medial temporal and parietal brain regions, including the retrosplenial cortex (RSC). By contrast, frontotemporal dementia (FTD) syndromes show generally intact spatial orientation at presentation. However, currently no clinical tasks are routinely administered to objectively assess spatial orientation in these neurodegenerative conditions. In this study we investigated spatial orientation in 58 dementia patients and 23 healthy controls using a novel virtual supermarket task as well as voxel-based morphometry (VBM). We compared performance on this task with visual and verbal memory function, which has traditionally been used to discriminate between AD and FTD. Participants viewed a series of videos from a first person perspective travelling through a virtual supermarket and were required to maintain orientation to a starting location. Analyses revealed significantly impaired spatial orientation in AD, compared to FTD patient groups. Spatial orientation performance was found to discriminate AD and FTD patient groups to a very high degree at presentation. More importantly, integrity of the RSC was identified as a key neural correlate of orientation performance. These findings confirm the notion that i) it is feasible to assess spatial orientation objectively via our novel Supermarket task; ii) impaired orientation is a prominent feature that can be applied clinically to discriminate between AD and FTD and iii) the RSC emerges as a critical biomarker to assess spatial orientation deficits in these neurodegenerative conditions.

KEYWORDS:

Alzheimer's disease; Frontotemporal dementia; Orientation; Retrosplenial cortex

PMID:
25913063
DOI:
10.1016/j.cortex.2015.03.016
[Indexed for MEDLINE]

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