Objective: We aimed to investigate whether striatal Dopamine transporter (DaT) uptake could be predicted by Neutrophil to lymphocyte ratio (NLR) or measures of disease severity in early PD.

Background: DaT SPECT Scan has a 95% sensitivity in detection of dopamine transporter deficit in clinically confirmed Parkinson disease (PD). NLR is higher in patients with PD and might open a window for early detection of PD [1].

Methods: Using Parkinson’s Progression Markers Initiative (www.ppmi-info.org/data), PD subjects with DaTSCAN™ imaging available at screening were recruited (n=391) along with 151 matched healthy controls (Table 1). Details of DaTSCAN™ have been described previously [2]. Data were analysed with a standardized volume of interest template for extraction of regional count densities in the left and right caudate and putamen. Average striatal binding ratios (SBR), was partially correlated with subject’s neutrophil to lymphocyte ratio controlling for age, sex, and disease duration in PD patients.

Results: NLR was negatively predicted by age and had a negative correlation with caudate region SBR values only in PD group. Older age correlated with more DAT deficit in normal group but not in PD group. Longer duration of disease predicted worse SBR scores in putamen of PD patients. As expected, putaminal and caudal SBR predicted as high as 72% of the total variance of NLR, in control and PD group respectively (Table 2). Olfaction dysfunction in PD group was negatively correlated with Putaminal DAT deficit. More severe motor symptoms and higher H&Y stage were associated with more sever DAT deficit in caudate and putamen in SPECT imaging of PD patients. In partial correlation analysis NLR was weekly but significantly correlated with caudate SBR in patients with PD, that persisted after adjustment for age and disease duration. NLR could not predict SBR in neither of striatal regions after adjustment for age and sex in control groups.

Conclusions: We demonstrated for the first time, a significant negative correlation between striatal DaT uptake, and NLR is drug naïve PD patients. As DaT uptake directly correlates with striatal neuronal loss, and neuroinflammation is believed to play a major role in early PD, our results put further spin on usage of NLR as a marker of early PD pathology and DaTScan as reliable tool to identify pathological progression of PD.

References: 1. Rahmani, M.H.F.R.M.H.A.S.S.S.S.M., White-Matter Changes Correlates of Peripheral Neuroinflammation in Patients with Parkinson’s disease. Journal of Neuroscience, 2017. 2. Rahmim, A., et al., Application of texture analysis to DAT SPECT imaging: Relationship to clinical assessments. Neuroimage Clin, 2016. 12: p. e1-e9.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/neuroinflammation-predicts-dompaminergic-deficit-in-early-parkinson-disease-dat-spect-imaging-study/