Apraxic disturbances in patients with mild to moderate Alzheimer's disease.

Twenty-two patients meeting the NINCDS-ADRDA diagnostic criteria for probable AD were included in the study, along with 10 matched controls. Praxic disturbances were investigated using eight tasks and the results were interpreted according to the neuropsychological model of Roy and Square modified by Rothi et al. (1988) [Aphasiology 21:381-388] which distinguishes a conceptual system concerned with knowledge of the action and function of gestures and a production system that effects gestures in the environment. Disturbance of the production system was found only in 17 patients. Disturbance of the production system was correlated to disturbance of verbal comprehension. The patients scored lower using the left hand than the right. Disturbance of the conceptual system was found in all patients and was not significantly correlated with other cognitive deficits. No significant difference in results was found according to the type of input to the conceptual system (visual or verbal). Deficits in tasks using real objects were correlated to disturbances of both the production and conceptual systems. Most patients performed poorly both in tasks exploring the conceptual system and in those exploring the production system. However, two patients performed badly in production tasks but had performances in the range of controls for conceptual tasks and one patient had the opposite pattern of dissociation. This provides evidence that the production and the conceptual system are independent. Impairment in the ability to perform everyday activities was correlated to disturbances of the conceptual system whereas poor performances in tasks exploring the production system or in using real objects were not.

Decreased awareness of cognitive deficits in patients with mild dementia of the Alzheimer type.

OBJECTIVE: To study the unawareness of cognitive deficits in patients with mild dementia of Alzheimer type (DAT). DESIGN: Retrospective study. We surveyed the medical records of outpatients meeting the NINCDS-ADRDA criteria for probable DAT who were able to complete the Cognitive Difficulties Scale (CDS) and had a close informant relative (IR) who could complete the family form of the same questionnaire. SETTING: A department of neurology in a general teaching hospital. SUBJECTS: Eighty-eight patients, aged 73.2+/-8.6 years with a mean MMSE score of 22.5+/-3.2. Fifty-two of the 88 patients had a follow-up examination after a mean interval of 21 months. METHODS: Awareness of cognitive deficits was mainly assessed as the difference between the scores on the CDS completed by the IR and the patient (Index of Unawareness, IU). Two secondary assessments of unawareness were performed: (1) an assessment by the clinician on the basis of the patient's answers to questions probing the awareness of memory deficits; (2) an evaluation by the IR of the frequency of behavioural manifestations of unawareness in everyday life. SPECT was performed in 78 patients to study the relationship between unawareness and the topography of perfusion deficits. RESULTS: Awareness of the cognitive deficits varied greatly between patients, according to the assessment method used and the stage of progression of the disease. Most patients with mild DAT were cognitively aware of their cognitive deficits but failed to appraise their severity and their consequences in everyday life. Decreased awareness was positively correlated with age and perfusion deficits in the frontal regions and negatively with the anxious symptomatology. However, the main correlate of unawareness was apathy. CONCLUSION: The nature of unawareness of cognitive deficits appeared to be more dimensional than categorical. In patients with mild dementia, decreased awareness appeared to be more related to affective disturbances, especially to emotional deficit or apathy, than to cognitive deficits.