Évaluation de l’anosognosie et ses enjeux dans la maladie d’Alzheimer

Anosognosia in the setting of Alzheimer's disease reduces the extent to which the subject can become involved in his or her care, it favors situations of danger, increases the distress of caregivers and increases the risk of early institutionalization. This explains why this symptom profile, which is common in the early stages of the pathology, has increasingly become a subject of research. Authors recall its definition, and the main models and assessment tools in Alzheimer's disease. These tools mostly relate to methods centered on the various dimensions of anosognosia. They concern a) the method of patient–caregiver discrepancy, which assesses the levels of anosognosia by way of the differential between the opinion of the family caregiver and that of the subject concerning the competences or difficulties of the subject in various dimensions of daily living; b) the prediction/performance discrepancy, which estimates the level of anosognosia from the discrepancy between the subject's predictions of success on different test items and his or her actual test results; and c) the clinician assessment method, which calls on a professional to ascertain the patient's degree of anosognosia. Other methods described as patient-centered have appeared recently, in particular phenomenological scales aiming to apprehend the experience of the subject by way of clinical interview, aiming to identify the processes and dimensions characterizing the condition. Anosognosia in Alzheimer's disease is positively associated with caregiver burden, overall cognitive decline, dysexecutive syndrome and apathy. It is negatively associated with depression, although this association is a subject of debate. The tools that have been validated in France are still too few [Antoine et al. (2004)], which explains the lack of interest in anosognosia in everyday clinical practice. Here again, there is no normative data to provide clinicians with some guidance. Recent research has underlined how anosognosia assessed by methods centered on dimensions (patient–caregiver discrepancies, prediction/performance discrepancies and clinician evaluation) is almost systematically associated with apathy, independently from the domains assessed (cognitive or behavioral disturbances, etc.). Thus, apathy appears as the most discriminant dimension in anosognosia according to the severity of the condition, which offers new perspectives for assessment in clinical practice. There are indeed numerous scales measuring apathy that have been validated in French, providing an evaluation by the family caregiver and the subject, and liable to generate an anosognosia index for the patient–caregiver discrepancy method. Depression, which is exacerbated by the awareness of disturbances, could raise the issue of denial, and more broadly of avoidance strategies, the implication of which in this symptom requires at least back-up by a causality between the two entities, and more qualitative investigations with the subject (clinical interviews to enable the subject to explain the reasons for his or her present thymic state). Thus, the phenomenological scales, better able to cast light on the processes at work in anosognosia (mechanisms, modes of expression) and on their particular impact on the caregiver, seem potentially valuable to gain knowledge of this particular symptom profile. These scales could then lead to preventive and therapeutic lines of action that are generally lacking in present-day clinical practice.