The sense of self is supported by several independent cognitive processes in Alzheimer's disease and self-reported age tracks cognitive impairment

Do patients with Alzheimer's disease loose themselves? The impact of dementia on the sense of self has been extensively studied over the past 15 years. However, most studies investigate only one marker of the self - such as mirror self-recognition or the use of the pronoun "I" - and do not track how this marker evolves in the course of the illness in comparison to other markers. This situation has resulted in fragmented findings rather than converging evidence for a coherent model of the self in dementia. In our two studies, we use a questionnaire to investigate four markers of the self simultaneously (self-knowledge, mirror self-recognition, the bodily distinction between self and other, and self-reported age) in the same 60 patients spread across three stages of Alzheimer's disease. This method allows us to determine whether these markers are impaired independently over the progression of the illness. Our results suggest that the sense of self relies on a complex structure supported by several independent cognitive processes that are impacted differently by the progression of dementia. In particular, despite the early deterioration of self-knowledge, patients at advanced stages of the disease seem to maintain a sense of self, rooted into mirror self-recognition and the bodily self. Furthermore, self-reported age predicts the level of cognitive impairment. We suggest that a better understanding of the stage at which each marker of the self breaks down can help clinicians support their patients better by targeting the preserved dimensions of their identity at any given point in the progression of their condition.