The case of a patient with Alzheimer's disease is reported and some considerations about the clinical individuality of the disease and the characteristics shown by the disintegration of behavior are made. In the study, the following methods were used: neurological examinations focused especially on movement disturbances, ecoencephalography, electroencephalography, cerebral cintilography, right carotid arteriography and cerebral biopsy. The clinical aspects of the disease, just as the correlation of the data obtained by the auxiliary methods allow the formulation of the diagnosis, confirmed by right frontal cerebral puncture. The patient's clinical context shows the basic syndromes: 1) frontal with fixative amnesia, lack of interest, deterioration of the consciousness of situation and of the intellectual level, bilateral apprehension reflex; 2) parieto-temporo-occipital with indifference for the left hemibody, for the visual hemifield and for the space of this side. In addition, there arises a serious complication of motor behavior (praxias) with the disintegration of all functional levels: instrumental (melokinesic apraxia), space linked to the body (ideomotor), Euclidean space (constructive) and real manipulation of objects (ideative). According to these two syndromes, pneumoencephalography has showed two areas of atrophy in the frontal region and in the parieto-temporo-occipital joint. The cerebral biopsy confirmed the clinical assumption showing the histopathological alterations of Alzheimer's disease. The case reported confirms the clinical individuality of Alzheimer's disease, within the chapter of the presenile dementia and the possibility of it's clinical diagnosis in life. The patient's behavior (apraxias) confirms the close correlation that exists on all levels of its disintegration, between disturbances of movement and disturbances of the Euclidean space, of the space centered in the body itself and of the concrete space for the manipulation of objects.