Objective: To evaluate the common and divergent dopaminergic and serotonergic impairment in Parkinson’s disease and dementia with Lewy bodies using 123I-FP-CIT imaging.

Background: Striatal dopaminergic pathways are impaired in both PD and DLB. The two conditions might presents with different extrastriatal dopaminergic and serotonergic impairment.  fifty-six PD patients without dementia, 41 DLB patients and 54 controls entered the study. Each patient underwent a standardized neurological examination and 123I-FP-CIT SPECT. For each subject, bindings of nigrostriatal and extrastriatal regions of interest were calculated from spatially normalized images. The occipital-adjusted specific to non-displaceable binding (SBR) in the different regions was compared among PD, DLB and controls adjusting for the effect of age, sex, disease duration and serotonergic/dopaminergic treatment.

Method: Fifty-six PD patients without dementia, 41 DLB patients and 54 controls entered the study. Each patient underwent a standardized neurological examination and 123I-FP-CIT SPECT. For each subject, bindings of nigrostriatal and extrastriatal regions of interest were calculated from spatially normalized images. The occipital-adjusted specific to non-displaceable binding (SBR) in the different regions was compared among PD, DLB and controls adjusting for the effect of age, sex, disease duration and serotonergic/dopaminergic treatment. A covariance analysis provided the correlates of local and long-distance regions with extrastriatal 123I-FP-CIT deficits.

Results: Both PD and DLB patients showed lower 123I-FP-CIT SPECT SBR in several regions beyond the nigrostriatal system, especially the insula, cingulate and thalamus. DLB patients showed significant lower 123I-FP-CIT SBR in thalamus compared to controls and PD patients. Thalamic and cingulate 123I-FP-CIT SBR deficits correlated, respectively, with limbic serotonergic and widespread cortical dopaminergic projections only in DLB patients while exhibited only local correlations in PD patients and controls. P

Conclusion: PD and DLB share insular dopamine deficits, whereas impairment of thalamic serotonergic pathways was specifically associated with DLB. Longitudinal studies will be necessary in order to evaluate the clinical value of extrastriatal 123I-FP-CIT SPECT assessment.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/extrastriatal-dopaminergic-and-serotonergic-pathways-in-parkinsons-disease-and-in-dementia-with-lewy-bodies-a-123i-fp-cit-study/