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Background: Dementia with Lewy Bodies (DLB) is responsible for cognitive-behavioural disorders but also for gait disorders. The latter are thought to be related to parkinsonism, but the neural bases of these disorders are not well known, especially in the early stages. The aim of this study was to investigate by volumetric Magnetic Resonance Imaging the neuronal basis of gait disorders in DLB patients, compared to Healthy Elderly Controls and Alzheimer's Disease patients., Methods: Clinical examination with motor assessment including 10-meter walking speed, one-leg balance and Timed Up and Go test, a comprehensive neuropsychological evaluation and 3D brain Magnetic Resonance Imaging were performed on 84 DLB patients, 39 Alzheimer's Disease patients and 22 Healthy Elderly Controls. We used Statistical Parametric Mapping 12 to perform a one-sample t-test to investigate the correlation between each gait score and gray matter volume (P ≤ 0.05 corrected for family-wise error)., Results: We found a correlation for DLB patients between walking speed and gray matter decrease (P < 0.05, corrected for family-wise error) in caudate nuclei, anterior cingulate cortex, mid-cingulate cortex, hippocampi, supplementary motor area, right cerebellar cortex and left parietal operculum. We found no correlation with Timed Up and Go test and one-leg balance., Conclusion: Gait disorders are underpinned by certain classical regions such as the cerebellum and the supplementary motor area. Our results suggest there may be a motivational and emotional component of voluntary gait in DLB subjects, underpinned by the cingulate cortex, a spatial orientation component, underpinned by hippocampi and suggest the involvement of brain processing speed and parkinsonism, underpinned by the caudate nuclei., Trial Registration: The study protocol has been registered on ClinicalTrials.gov. (NCT01876459) on June 12, 2013., (© 2024. The Author(s).)

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.