Background Neurodegenerative diseases are marked by changes in personal identity, including the self‐concept (SC), which refers to a collection of knowledge about oneself, made up of personal semantic information. Modifications of the Self have been extensively investigated in Alzheimer's disease (AD), whereas it has never been studied in dementia with Lewy bodies (DLB). Yet, key regions for Self‐processing such as the medial prefrontal, the anterior cingulate and the insular cortices, are damaged early in the course of DLB. Thus, the purpose of this study was to investigate the SC integrity and to explore its neuroanatomical correlates in early DLB as compared to AD and normal ageing. Method Twenty prodromal to mild DLB patients were compared to twenty‐one prodromal to mild AD patients, and to twenty‐one healthy control subjects, matched in terms of age and educational level. For all participants, SC was assessed using the Twenty Statements Test (TST) during which the subjects were asked to produce up to twenty affirmations answering the question: who am I? Behavioral performance was compared between the groups. 3D MRI images were acquired for DLB patients and correlational analyses were performed using voxel‐based morphometry (VBM). Result Behavioral results obtained in the TST showed significantly decreased performances in both DLB and AD groups compared to healthy control subjects (p<0.001). Moreover, DLB patients tended to produce less Self‐affirmations than AD patients. Additionally, correlational analyses between behavioral scores and neuroimaging data in the DLB group revealed positive correlations between the number of produced Self‐affirmations and grey matter volume in the medial and orbitofrontal prefrontal cortices and in the lateral temporal cortex, among other regions (central sulcus, hippocampus, cerebellum). Conclusion Our behavioral results confirmed that SC is affected from the early stage in both DLB and AD, and tends to be even more deteriorated in DLB. Interestingly, VBM analyses revealed that decreased performance in DLB patients was related to focal atrophy in regions such as medial prefrontal and lateral temporal cortices, which are central in the networks of Self‐processing and semantic memory, respectively.

The insula is a multiconnected brain region that centralizes a wide range of information, from the most internal bodily states, such as interoception, to high-order processes, such as knowledge about oneself. Therefore, the insula would be a core region involved in the self networks. Over the past decades, the question of the self has been extensively explored, highlighting differences in the descriptions of the various components but also similarities in the global structure of the self. Indeed, most of the researchers consider that the self comprises a phenomenological part and a conceptual part, in the present moment or extending over time. However, the anatomical substrates of the self, and more specifically the link between the insula and the self, remain unclear. We conducted a narrative review to better understand the relationship between the insula and the self and how anatomical and functional damages to the insular cortex can impact the self in various conditions. Our work revealed that the insula is involved in the most primitive levels of the present self and could consequently impact the self extended in time, namely autobiographical memory. Across different pathologies, we propose that insular damage could engender a global collapse of the self.

Background and objectives Photophobia is a sensory disturbance provoked by light. Little is known about the association between photophobia and dementia with Lewy bodies (DLB). In this study, we aimed to identify the frequency and the neural basis of photophobia in prodromal and mild DLB. Methods One hundred and thirteen DLB patients, 53 Alzheimer's disease (AD) patients, 20 AD and DLB patients, 31 patients with other neurocognitive diseases (including prodromal and mild demented patients), and 31 healthy elderly controls were included in this case–control study. Photophobia was systematically looked for and compared between groups. Among a selection of 77 DLB patients, we used voxel‐based morphometry (VBM) to compare those with and those without photophobia (gray matter volume; SPM12, XjView, and Matlab R2021b software). Results The frequency of photophobia was higher in the DLB group (47.3%) than in the other groups (p = 0.002). The photophobia questionnaire score was higher in the DLB group than in the AD group (p = 0.001). Comparison between DLB patients with and those without photophobia showed decreased gray matter in the photophobia subgroup, in the right precentral cortex, in the eyelid motor region of Penfield's homunculus (p = 0.007, family‐wise error [FWE] corrected). Conclusions Photophobia is a quite frequent symptom of prodromal and mild DLB. The neural basis of photophobia in DLB involves the right precentral cortex, which could have a role in the decrease of cerebral excitability, but also the motricity of the eyelids.

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.