The hypothesis that Alzheimer's disease (AD) and vascular dementia (VD) may be associated with specific patterns of neuropsychological dysfunction was tested by assessing sensory-motor performance, attention, memory, visuospatial functions, verbal ability, and intelligence in AD (N = 83) and VD (N = 42) patients stratified into four levels of severity based on the Mini-Mental State Examination. Results showed a progressive deterioration due to severity of dementia in both AD and VD patients in all cognitive tasks, but not in the sensory-motor tasks, and no significant interaction between type and severity of dementia in any measure, indicating a similar pattern and course of neuropsychological deterioration in AD and VD. Yet it was possible to differentiate the two groups with moderate success using tests drawing predominantly on motor speed and, to a lesser extent, on cognitive speed. In all these speeded tests, the AD patients outperformed the VD patients.