Imagine that you’re hosting a burger party, and you have two different types of patties – beef and turkey. You also have two bowls of toppings – one with barbecue sauce and one with ketchup. Now, depending on the type of patty you choose, it will interact differently with the toppings. Similarly, in this study, researchers investigated the effect of amyloid – a protein often associated with Alzheimer’s – on dopamine depletion in Lewy body diseases (LBD), such as Parkinson’s disease (PD) and dementia with Lewy bodies. They found distinct patterns in how amyloid influenced dopamine availability in different parts of the brain, specifically the anterior putamen, posterior putamen, caudate, and ventral striatum. Interestingly, only PD patients with amyloid showed decreased dopamine availability in the anterior and posterior putamen. The presence of amyloid did not directly correlate with worse motor symptoms in both groups, but it indirectly affected parkinsonian motor symptoms mediated by putaminal dopamine availability in PD patients alone. This research sheds light on the intricate interactions between α-synuclein and amyloid pathology in LBD, which vary depending on the specific type of LBD. To dive deeper into this fascinating study, check out the full article!

IntroductionConcomitant amyloid pathology is not uncommon and contributes to the clinical characteristics of Lewy body disease (LBD). We investigated the effect of amyloid on striatal18F-FP-CIT uptake patterns in LBD, including Parkinson’s disease (PD) and dementia with Lewy bodies.MethodsWe enrolled 125 patients with LBD who underwent18F-florbetaben positron emission tomography (PET) and18F-FP-CIT PET. Patients were divided into amyloid-positive and amyloid-negative groups. We investigated the effect of amyloid on striatal dopamine transporter (DAT) availability, depending on the type of LBD, using general linear models with interaction analysis after controlling for age, sex, education, deep white matter hyperintensity (WMH), periventricular WMH, and cognitive status.ResultsThere was a significant interaction effect between the disease group and the presence of amyloid on DAT availability in the anterior putamen, posterior putamen, caudate, and ventral striatum. In the presence of amyloid, only the PD group exhibited decreased DAT availability in the anterior and posterior putamen. In both groups, the presence of amyloid was not associated with DAT availability in the caudate and ventral striatum. The presence of amyloid was not directly related to the worse parkinsonian motor symptoms in both groups. However, there was a significant indirect effect of amyloid on parkinsonian motor symptoms, which was mediated by anterior and posterior putaminal DAT availability in the PD group alone.DiscussionThis study demonstrates different amyloid-dependent or amyloid-independent18F-FP-CIT PET patterns in patients with LBD, suggesting distinctive interactions between α-synuclein and amyloid pathology based on the type of LBD.

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