Assessment of cerebral perfusion alterations in dementia with Lewy bodies and Alzheimer's disease.

Background: Dementia with Lewy bodies (DLB) and Alzheimer's disease (AD) are common forms of dementia, characterized by overlapping clinical symptoms. Functional neuroimaging can provide valuable information for precise diagnosis. Our objective was to explore cerebral perfusion alterations in DLB and AD, and to determine which perfusion parameters are helpful in distinguishing DLB and AD. Methods: A total of 25 DLB patients, 34 AD patients, and 40 normal controls (NC) underwent neuropsychological testing and pseudo-continuous arterial spin labeling (pcASL) for assessing cerebral perfusion [mean cerebral flow (mCBF); arterial transit time (ATT)] indexes. Differences in perfusion indexes among the three groups were analyzed and the family-wise error (FWE) was used for multiple comparisons. Spearman analysis assessed the relationships between the mCBF and neuropsychological scores [mini-mental state examination (MMSE); Montreal Cognitive Assessment (MoCA)]. A receiver operating characteristic (ROC) analysis was conducted to evaluate the performance and discriminant value of different perfusion indices in distinguishing between the two diseases. Results: Compared with NC, the mCBF of patients with DLB was reduced mainly in the bilateral frontal lobe, bilateral parietal lobes, bilateral temporal lobes, and the right occipital lobe. AD patients showed lower mCBF mainly in the bilateral frontal lobes, the right temporal lobe, and the left parietal lobe. Compared with AD, DLB patients showed decreased mCBF in the bilateral frontal and parietal lobes. ATT in almost all major arterial regions was prolonged in DLB and AD when compared to NC. Compared with AD, ATT was significantly prolonged in DLB (P<0.05). Furthermore, the DLB demonstrated a significant positive correlation between mCBF and MMSE scores, particularly in regions such as the left superior parietal lobule (r=0.596, P=0.002) and the right precuneus (r=0.498, P=0.01). Similarly, AD exhibits a positive correlation between mCBF and MMSE scores within regions, such as the right middle temporal gyrus (r=0.550, P=0.001) and the left inferior parietal lobule (r=0.571, P<0.001). The perfusion indexes could help distinguish DLB from AD. Conclusions: DLB demonstrates a different pattern of regional blood flow reduction and prolonged ATT, which is different from that in AD. ASL-derived parameters provide critical discriminative information for differentiating DLB and AD.