Neuropsychological markers of dementia on visual-spatial tasks: a comparison between Alzheimer's type and vascular forms of dementia.

The incidence of the "closing-in" phenomenon and of the tendency to give "primitive answers" on the Raven's Colored Matrices was studied in 50 normal subjects and in two groups of Alzheimer's type (n = 41) and of vascular (n = 35) dementia patients, carefully matched as for the overall severity of dementia and the degree of visual-spatial impairment. The aims of this research were to determine if these patterns of behavior can be considered as neuropsychological markers of dementia and if their incidence is similar in the two dementia groups. Results show that both the closing-in phenomenon and the tendency to give globalistic and odd responses on the Raven's Colored Matrices are good markers of dementia and that, in particular, they point to a degenerative, rather than to a vascular form of dementia. From the clinical point of view, these data suggest that a qualitative analysis of the patient's behavior can increase the diagnostic efficacy of neuropsychological tests and that neuropsychological markers of dementia point more to Alzheimer's disease (considered as the most prototypic form of dementia) than to a vascular form of dementia even when the two groups of patients are well balanced in terms of visual-spatial impairment and the overall severity of dementia.