Using clinico-psychopathological, clinico-neuropsychological and computer-aided tomography approaches, material differences were ascertained between groups of patients with Alzheimer's disease (AD) and senile dementia (SD) in terms of the clinical parameters, including the age at which the disease sets in; the disease standing; the build-up features of the patients; the frequency of diverse exogenous and environmental actions at the premorbid stage and at the disease debut; the psychopathological structure of dementia and the initial disease manifestations. The clinical differences indicated were in agreement with different structures of the neuropsychological syndrome marked by the impairment of higher mental functions in AD and SD and with different structures and topography of alterations in the medulla, discovered by means of computer-aided studies. The differences in the clinical and morphofunctional characteristics of AD and SD allow a conclusion that AD and SD are clinically independent disease entities within the framework of the common group of the Alzheimer's type dementias.