Neural basis of writing in prodromal to mild dementia with lewy bodies.

OBJECTIVES: We have previously demonstrated difficulties in written production in dementia with Lewy bodies (DLB) patients. We now aim to determine the neural correlates of writing production in DLB, combining clinical data and structural MRI measures. METHOD: Sixteen prodromal to mild DLB patients were selected to participate in the study. The GREMOTS test was used to assess writing production. Using three-dimensional T1 brain MRI images, correlations between the GREMOTS test and grey matter (GM) volume were performed using voxel-based morphometry (VBM; SPM12, XjView and Matlab R2021b softwares). RESULTS: VBM analysis (p < 0.001, uncorrected) revealed a positive and significant correlation between both left anterior insula and left supramarginal gyrus GM volumes and DLB patients' ability to write logatoms using the phonological route. The handwriting deficit was negatively and significantly correlated to the supplementary motor area. The parkinsonism-like characteristics of agraphia were negatively and significantly correlated with both right anterior and right posterior cerebellum GM volumes. Our study also revealed a negative and significant correlation between grammatical spelling impairments and an area of the orbitofrontal gyrus, and a negative and significant correlation between supramarginal gyrus and general slowness in dictation tasks. CONCLUSION: Writing disorders in early DLB patients appears to be GM decreases in several brain regions, such as the left anterior insula, the left supramaginal gyrus, as well as two areas of the right cerebellum.

Neural basis of impaired narrative discourse comprehension in prodromal and mild dementia with lewy bodies.

Narrative discourse (ND) comprehension is a complex task that implies not only linguistic abilities but also other cognitive abilities, including efficient executive functioning. An executive dysfunction has been described in dementia with Lewy bodies (DLB) from the early stage. Here, we question the link between executive dysfunction in DLB and narrative comprehension. The aim of our study was to evaluate ND comprehension and to investigate the neuroanatomical basis for its impairment in the early stage of DLB. DLB patients (N = 26) and controls (N = 19) underwent the ND comprehension test of the Montreal Protocol for Evaluation of Communication (MEC). An additional, qualitative analysis was conducted on their verbal productions. Cognitive tests assessing verbal episodic memory, executive functions, naming and oral syntactic comprehension were also performed. Brain gray matter correlates of the ND comprehension test were examined using voxel-based morphometry (VBM). An ND comprehension impairment was found for prodromal and mild DLB patients as compared to controls. These difficulties were correlated with the Frontal Assessment Battery (FAB) score. ND comprehension impairment in DLB was further characterized by a deficit in the organization and the logic of the discourse. Moreover, VBM analysis revealed a correlation between striatal gray matter volumes and DLB patients' ability to extract and organize relevant information (p < 0.05, FDR correction, cluster level). The ND comprehension impairment in DLB patients could be related to their executive dysfunction through a deficit of information selection and organization that correlates with the volumetric reduction of striatal gray matter.

[Writing in prodromal and mild dementia with Lewy bodies: an exploratory and preliminary study]. / La production écrite dans la maladie à corps de Lewy prodromale à légère : une étude exploratoire préliminaire.

Dementia with Lewy bodies (DLB) is the second most common form of dementia in elderly patients. In the early stages, it shares many clinical and pathological features with other neurocognitive disorders such as Alzheimer's disease, making early and accurate diagnosis challenging. While written production has been shown to be sensible to pathological aging even before the onset of spoken language disorders, no research has been conducted on this aspect in DLB patients, particularly at the prodromal or mild stages. OBJECTIVE: In order to better characterize their cognitive profiles, our speech therapy study aimed to assess the ability of prodromal or mild DLB patients in writing production. METHODS: Seventeen prodromal to mild DLB patients underwent written tests selected from the French language assessment corpus GREMOTS. The protocol included dictations of words, logatoms, and sentences. These tests were completed with a self-assessment questionnaire about writing disability and an observational table of writing behavior. RESULTS: 18% of patients had a deficit score in dictation of words, 41 % of patients had a deficit score in dictation of logatoms and 35% of patients had a deficit score in dictation of sentences. 71% of patients had a subjective complaint about their handwriting quality. The assessment of handwriting quality also showed difficulties for 76% of patients, with graphic motor pattern disorders and motor symptoms associated with parkinsonism dysgraphia. Finally, our results suggest an impact of working memory, attentional and executive function impairments on logatoms production, and an impact of working memory impairment on long sentences production and grammatical agreements. DISCUSSION: These findings are promising and may improve our knowledge of the prodromal and mild stages of DLB. They may also contribute to improve early diagnosis and clinical practice.

[Narrative discourse in dementia with Lewy bodies and Alzheimer's disease]. / Le discours narratif dans la maladie à corps de Lewy et la maladie d'Alzheimer.

Dementia with Lewy bodies (DLB) is the second most common form of dementia, after Alzheimer's disease (AD). Subjects with DLB remain under-diagnosed, especially in the early stage of the disease, when they can show subtle neurocognitive disorders similar to subjects with AD. In order to refine the differential diagnosis between these two neurodegenerative diseases and to improve patients' care, our speech therapy study aimed to analyze their ability to tell a story by producing a narrative discourse (ND). METHOD: 25 participants with DLB and 12 participants with AD underwent a ND test based on an illustrated story. The test was selected from the French language assessment corpus GREMOTS. The grading of the ND was done according to the following six parameters: lexicon, syntax, pragmatics, presence of the main actions, quality of discourse and informativeness. RESULTS: In the early stage, a quarter of the participants with DLB are under cut-off score for ND, and this proportion strongly increases in the advanced stage. In contrast, all the participants with AD show a pathological ND in both stages. In the early stage, the ND abilities appear significantly better preserved in participants with DLB than in participants with AD. No difference is found in the advanced stage. This result highlights two distinct language profiles, with the participants with AD being significantly less informative than the participants with DLB in the early stage. Furthermore, the participants with DLB show pathological scores spreading over the six parameters, whereas the participants with AD have more selective impairments. Indeed, the informativeness of participants with AD is 100% pathological while their syntax is 100% preserved. DISCUSSION: These results are encouraging as they could enable speech therapists to better adjust their follow-up according to the linguistic profile of the patients and to educate caregivers more appropriately. Further research on language issues in DLB and AD is essential.