Affiliations: [a] Neuroimaging Laboratory, Santa Lucia Foundation, IRCCS, Rome, Italy | [b] Department of Clinical and Behavioural Neurology, Santa Lucia Foundation, IRCCS, Rome, Italy | [c] Department of Neuroscience, University of Rome ‘Tor Vergata’, Rome, Italy | [d] Institute of Neurology, Universitá Cattolica, Rome, Italy | [e] Clinical Imaging Sciences Centre, Brighton & Sussex Medical School, Falmer, UK
Correspondence:
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Correspondence to: Dr. Marco Bozzali, Via Ardeatina 306, 00179 Rome, Italy. Tel.: +39 06 5150 1324; Fax: +39 06 5150 1213; E-mail: m.bozzali@hsantalucia.it.
Abstract: Constructional apraxia (CA) is often, but not always, observed in patients with Alzheimer's disease (AD). CA is usually explained by impairment of either basic perceptual and motor abilities, or executive functions. This study aims to evaluate the structural correlates of CA in AD. Forty-eight patients with AD and 20 healthy age-matched controls underwent a thorough neuropsychological investigation and an MRI scan to collect high-resolution T1-weighted data. Patients were classified as having (ADca) or not having (ADnonca) CA based on performance on the Freehand copying of drawings task. T1-weighted volumes were process according to the voxel based morphometry protocol, to assess the presence of significant differences in local to grey matter volumes in patients compared to controls and in ADca compared to ADnonca. Post-hoc, the mean grey matter volume of clusters that resulted significantly different between groups was regressed against the neuropsychological scores in which the two patient groups performed differently. A pre-senile disease onset was significantly more frequent in patients with CA compared to ADnonca. ADca patients also showed worse performances than patients with ADnonca at some tests requiring the processing of visuo-spatial data and testing working memory. They also showed widespread reductions in grey matter volume, mainly located in areas known to be implicated in object recognition and localization, and in maintenance and re-orienting of spatial attention. These findings suggest that the occurrence of CA in AD is often associated with a peculiar clinical onset (i.e., pre-senile), neuropsychological profile, and distribution of grey matter atrophy.
