Lewy body diseases, including Parkinson’s disease (PD) and dementia with Lewy bodies, often involve mild cognitive impairment (MCI) at diagnosis (MCI-LB). Previously, we found that patients with PD without MCI have already a problem with sentence comprehension with altered task-dependent functional connectivity (Novakova et al. 2023). Our current aim was to assess syntactic comprehension deficits in MCI-LB patients and explore the neural correlates using functional connectivity analysis of the striatum and language networks. In ongoing second arm of this study, we aim to investigate the effects of repeated sessions of home-based tDCS on sentence comprehension. Our behavioural results showed disturbed sentence comprehension in MCI-LB patients with altered taskdependent functional connectivity from the striatum to the cuneus/precuneus/lingual gyrus and to left supramarginal gyrus. We found also decreased connectivity in language networks in MCI-LB patients. In noncanonical task it was specific for dorsal pathway, which is in line with literature that links syntax specifically to this dorsal language pathway.