Do visuospatial and constructional disturbances differentiate frontal variant of frontotemporal dementia and Alzheimer's disease? an experimental study of a clinical belief.

Background: In recent years several attempts have been made to distinguish frontotemporal dementia (FTD) from Alzheimer's disease (AD) on neuropsychological grounds; in particular, it has been suggested that FTD patients show spared spatial abilities with respect to AD patients.

Objective: We aimed at verifying whether patients with the frontal variant of frontotemporal dementia (fv-FTD) and AD patients perform differently on visuospatial and constructional tasks.

Methods: We assessed a wide range of visuospatial abilities and provided a qualitative analysis of constructional performances in 14 fv-FTD patients and 11 AD patients, matched for general cognitive abilities.

Results: The two groups of patients achieved similar scores on two copying tasks, presented similar drawing procedures in copying Rey complex figure and made a similar quantitative and qualitative pattern of errors in copying simple geometrical drawings. Moreover, no significant difference was found between fv-FTD and AD patients on a specific battery for visuospatial abilities.

Conclusions: Our data and a review of the literature suggest that basic visuospatial and constructional skills cannot be taken as a reliable diagnostic criterion for distinguishing fv-FTD and AD at a mild to moderate disease stage and that the clinical belief of spared spatial abilities in fv-FTD has to be referred to the lack of topographic disorientation in comparison to AD.