Dementia with Lewy body builds significant part of synucleinopathies. Our aim is to study changes in fMRI dynamic functional connectivity characterising the prodromal stage of mild cognitive impairment with Lewy body MCI LB. Sliding window analysis (rectangle windows with length of 61 scans and overlap 90). We computed Pearson correlation coefficients between signals in each window and clustered the correlation matrices with k-means clustering algorithm. 4 states were recommended. We identified the brain state of each time window and evaluated their coverage number of windows spent in the state relative to all windows and density (normalized number of occurrences). Strong feature of state 4 is commonly observed anticorrelation of DMN with most of other resting state networks. Lower normalized number of time spent in state 4 in MCI LB might reflect impairment of prodromal state with respect to healthy controls. Directly proportional relation of state 4 coverage with memory z score in MCI LB group suggests higher damage of memory function in MCI LB participants who spent less time in this state dFC can play role as reasonable parameter for classification of MCI LB patients. Observed results are in concordance with our observations on pilot data.