Self, insula and dementia with Lewy bodies

Abstract

Background The objective is to review in the literature evidence of the relationship between the Self, the insular cortex, and Dementia with Lewy bodies (DLB). The notion of “Self” encompasses a subjective part that integrates the most internal bodily phenomena of self‐awareness, and an objective part that sustains autobiographical memory and its most specific details. Modifications of the Self, such as anosognosia and personal identity, or autobiographical memory deterioration, are frequently reported by relatives and noticed by clinicians, jointly with insular atrophy, which occurs early in the course of the disease. Method We performed research on PubMed and Google Scholar, using MeSH subheadings and keywords, limited to papers in English; 226 publications contributed to the review. The terms “Lewy bodies”, “Insula”, “Self” and different aspects related to the self, such as “subjective sense of self”, “self‐concept” and “autobiographical memory” were used to denote the themes of interest. Result The evidence suggest that insula is a multiconnected brain region involved in processing varied aspects of the self. On the one hand, insula’s posterior part integrates primary interoceptive representations through sensorimotor processes, and on the other hand insula’s anterior part sustains and integrates viscerosensory responses, socio‐emotional processing and cognitive functions, allowing the emergence of self‐awareness. In addition, changes in personal tastes resulting from insular atrophy have been highlighted in DLB. However, there is, to date, little work exploring the different components of the self (i.e. subjective sense of self; self‐concept; autobiographical memory) in DLB. Conclusion Based on our literature review, it seems that no experimental work have ever been performed on the Self in DLB. Numerous aspects related to the Self, from the most primitive to more elaborated ones are worthy of being studied in this affection, whose anatomic peculiarity sets in early insular damage. We intend to investigate these questionings in DLB, compared to Alzheimer disease – which is characterized by an early deterioration of episodic autobiographical memory – and healthy elderly population, by combining behavioral measures and multimodal neuroimaging, with a particular interest for the insular cortex.