Parkinson's disease with dementia (PDD) and dementia with Lewy bodies (DLB) both commonly exhibit brain Lewy body pathology and similar end-stage symptoms, but early symptoms differ. To clarify these differences, we compared the demographic characteristics, symptoms, cognitive and affective functioning, activities of daily life, and neuroimaging results between PDD (n = 52) and DLB (n = 46) patients. In measures of cognitive functioning, PDD patients had worse Hasegawa dementia scale-revised (HDS-R) scores (11.2±4.8) and better frontal assessment battery (FAB) scores (11.3±4.1) compared with DLB (17.0±6.4, p = 0.013 and 8.6±4.7, p = 0.039, respectively). DLB patients performed worse than PDD patients in "orientation to place" tasks. In affective functions, DLB patients had worse GDS (7.6±3.4) and ABS (9.9±5.3) scores than PDD patients (5.1±4.1 and 4.8±3.0, respectively). 99mTc-ECD images showed greater CBF in the whole cingulate gyrus and a lower CBF in the precuneus area in DLB than in PDD. These results suggest that PDD patients' lower average scores for "repetition" (MMSE), "recent memory" (HDS-R), and "lexical fluency" (FAB) were related to lower CBF in the cingulate gyrus than in DLB. Furthermore, DLB patients' poorer average subscale scores of "orientation to place" (MMSE) and "similarities", "conflicting instructions", and "go-no go" (FAB) tasks may be related to the lower CBF in the precuneus area in DLB than PDD.
Keywords: 99mTc-ECD images; Affective function; Parkinson’s disease with dementia; cognitive function; dementia with Lewybodies.