In PD and DLB, a clear correspondence between structural and functional connectivity changes in specific networks is difficult to draw, in part because DLB has yet to be linked to a particular network detectable with resting-state fMRI.106 DTI demonstrates microstructural abnormalities in the basal ganglia of PD patients,107-109 but evidence of structural disconnection within this circuit is limited.109,110 Reduced connectivity in the frontal and parietal association tracts has been reported but without detecting a clear pattern of WM involvement.111-113 PD patients who develop dementia show a specific involvement of the posterior cingulum compared with both PD and controls.114,115 In DLB, the most consistent finding is a reduction of connectivity in the inferior longitudinal fasciculus,114,116-118 which connects the posterior temporal and occipital visual cortices, a finding in line with the occurrence of visual hallucinations in these patients.116 In addition, DLB patients show reduced connectivity between fronto-temporal and fronto-occipital regions compared to controls.114,118 This pattern of WM disruption is overall similar to that detected in patients with PDD,114 and AD,118 but damage in the visual association areas is more pronounced in DLB
