Dopamine Transporter, Depression and Anxiety Differences Between Tremor-Predominant and Non-Tremulous PD are Already Evident Within 2 Years of PD Diagnosis
Objective: PD patients can be partitioned into two groups, denoted Tremor Dominant (PD-TD) and non-tremor-dominant (PD-NTD) based on their MDS-UPDRS III subscores. Is this distinction correlated with the outcomes of cognitive tests, biomarkers, and dopaminergic imaging within 2 years of the PD diagnosis?
Background: The classification of Parkinson’s disease (PD) patients into tremor-dominant (PD-TD) and non-tremor-dominant (PD-NTD) is commonly used clinically. The distinction is based on the relative difficulty the patient has with tremor vs akinetic or rigid aspects of PD, as reflected in scores on specific questions in the MDS-UPDRS III. The Parkinson’s Progression Markers Initiative (PPMI) cohort is a large observational clinical study aimed at verifying progression markers of Parkinson’s disease. This cohort provides us with the data for answering this question. Indeed, it contains 400 patients with a diagnosis of PD within 2 years of the baseline visit and an exhaustive collection of assessments.
Methods: We have studied a comprehensive collection of PPMI measurements, including neurological and psychological tests, biofluid-based biomarkers, and dopamine transporter Imaging acquired at the baseline visit. In each case, we conducted a Wilcoxon test for the difference of the median within the two groups PD-TD and PD-NTD and corrected for multiple testing.
Results: PD-NTD patients were clinically more severe in regards to their motor and non-motor symptoms of PD, as measured with the MDS-UPDRS I and II, as well as more likely to have depression and anxiety symptomatology. In addition, there were very significant dopamine transporter imaging (DaTscan) differences between the PD subtypes: PD-TD patients had less of a reduction in uptake in the striatum, caudate, and putamen compared to PD-NTD.
Conclusions: The distinction between PD-TD and PD-NTD is well established using neurological exams. However, we have shown that the depression, anxiety and DaTscan measurements are also significantly different between these 2 groups at the earliest stages of the disease.
Q. Hu, F. Zhou, C.P. Jedynak, L.S. Rosenthal, Z. Mari, B.M. Jedynak. Dopamine transporter, depression and anxiety differences between tremor-predominant and non-tremulous PD are already evident within 2 years of PD diagnosis [abstract]. Mov Disord. 2016; 31 (suppl 2).