Background: Cummings et al, 1987, hypothesized that Alzheimer dementia type (ADT) patients would present poorer performances than vascular dementia (VD) patients on the neuropsychological tests that mainly involve cortical neurological structures, and that VD would perform worse on tests that mainly involve subcortical structures. The main purpose of the research was to identify a cognitive impairment pattern that discriminates the type of dementia in the initial stages.
Method: Two groups of patients, one affected by mild ADT (n = 30) and the other by multi-infarct dementia (VD, n = 30) were given a neuropsychological battery. The battery was composed by Temporal Orientation (Benton et al.); Vocabulary, Similarities, Digits, Coding and Kohs (WAIS) of Wechsler; the Colour-Form Test of Weigh; the Trail Making Test (A and B) (Halstead-Reitan Neuropsychological Battery); Tapping (McQuarrie); Logical Memory, Visual Memory and Paired Association (Wechsler Memory Scale) of Wechsler; Delayed Memory (Russell). The two groups were similar in age and socio-cultural features. The z-score and its statistical significance on the Mann-Whitney test were made and we performed an exploratory discriminant analysis to the classification.
Results: In general, results were poorer in the ADT group. But we detected no significant differences in the tests, although some test (Immediate Visual Memory and Kohs' Blocks) almost reached significance. The discriminant analysis reached a classification of the 67% of the subjects into the ADT group and the 70% of the subjects into the VD group.
Conclusions: In the initial stages of dementia it is difficult to differentiate between a cortical pattern of cognitive impairment in ADT and a subcortical pattern in VD, a distinction that the other researchers have reported. When complex tests were used the performance depended on the coordination of multiple related systems. These findings are in agreement with the holistic models of higher mental functions.