Abstract
This study investigated clinical and neuropathological differences between DLB and PDD. 52 PDD and 16 DLB cases from the Queen Square Brain Bank (QSBB) for Neurological disorders were included. Comprehensive clinical data of motor and cognitive features were obtained from medical records. Neuropathological assessment included examination of CAA, Lewy body and AD pathology. CAA was more common in DLB than in PDD (P=0.003). The severity of CAA was greater in DLB than in PDD (P=0.009), with significantly higher CAA scores in the parietal lobe (P=0.043), and the occipital lobe (P=0.008), in DLB than in PDD. The highest CAA scores were observed in cases with APOE ε4/4 and ε2/4. Survival analysis showed worse prognosis in DLB, as DLB reached each clinical milestone sooner than PDD. Absence of dyskinesia in DLB is linked to the significantly lower lifetime cumulative dose of levodopa in comparison with PDD. This is the first study which identified prominent concurrent CAA pathology as a pathological substrate of DLB. More prominent CAA and rapid disease progression as measured by clinical milestones distinguish DLB from PDD.
Highlights
APOE genotype was determined in 58 cases (PDD 46, Dementia with Lewy bodies (DLB) 12) using DNA extracted from frozen cerebellar tissue using polymerase chain reaction (PCR) followed by restriction enzyme digestion [42]
Tremor was less frequent in the DLB group (56.3%) than in the Parkinson’s disease dementia (PDD) group (84.6%) (P = 0.034)
Dyskinesia was absent in DLB cases compared to 71.2% of PDD, (P < 0.001) which is likely to relate to significantly lower lifetime cumulative dose of levodopa in DLB (P < 0.001)
Summary
PDD and DLB, currently characterized as a clinical spectrum of disorders and referred to as Lewy body. Cortical Lewy bodies are the main neuropathological hallmark of Lewy body dementias [1]. Previous studies demonstrated that cortical Lewy bodies correlate with dementia in PD [12,13,14], with Lewy bodies in the frontal and cingulate gyrus correlating with the severity of cognitive impairment in PD and PDD [15]. Neuropathological differences are relatively minor [17], and the main differentiating features are that DLB has less severe neuronal loss in the substantia nigra [18] and more severe AD pathology [19,20]
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