Objective: 1. To investigate prevalence of caudate dopaminergic dysfunction as measured by 123I-FP-CIT in a large cohort of early stage (< 2 years disease duration) untreated PD patients.

2. To determine if differential patterns of caudate dopaminergic loss noted on initial 123I-FP-CIT images at PD diagnosis correlate with subsequent clinical patterns.

Background: Neuroimaging of presynaptic nigrostriatal dysfunction in early PD has shown non-uniform striatal dopaminergic loss, with more pronounced dopaminergic loss in the putamen compared to the caudate. However, the degree of caudate involvement in early PD and its predictive value on subsequent clinical progression has not been studied in large patient cohorts.

Methods: PD patients and healthy controls (HC), with complete imaging and clinical follow-up for 4 years, were identified from the Parkinson’s Progression Markers Initiative database. We investigated the numbers of early PD patients with impaired caudate function as determined by reduced 123I-FP-CIT uptake in one caudate, both caudates and PD patients with normal caudate uptake. Reduced 123I-FP-CIT uptake for both caudates was determined by taking a value two standard deviations below the HC’s mean caudate uptake

Results: Screening imaging was available on 405 PD patients and 177 HC. Of the 405 PD patients, 215 (53.1%) had an unaffected caudate (PD-UC), 99 (46%) had a unilateral affected caudate (PD-UAC) and 91 (22.5%) had a bilateral affected caudate (PD-BAC).  

Complete 4 year follow-up data was available for 149 (36.8%) PD patients and 119 (67.2%) HC. PD patients were allocated to PD-UC (n=80, 53.7%), PD-UAC (n=34, 22.8%) and PD-BAC (n=35, 23.5%). All PD patients remained with a diagnosis of PD at 4 years.

There was no statistical difference between group’s demographics and clinical markers of disease severity or cognitive scores at baseline.

At 4 year follow-up, there was a significant negative correlation between decreasing MOCA score and PD groups (Rs= -17.2, P=0.036). The PD-BAC was found to have a statistically significant lower mean MOCA score compared to PD-UC (U=987, p=0.011) and PD-UAC (U=411, P=0.026). 45% of PD-BAC had developed cognitive impairment (p=0.01) compared with PD-UC (25%), PD-UAC (18%) and controls (5%).

Conclusions: We conclude that early bilateral caudate involvement on 123I-FP-CIT SPECT can be seen in a subgroup of PD patients and is predictive of subsequent cognitive decline in PD patients.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/early-caudate-involvement-in-parkinsons-disease-may-predict-future-cognitive-decline/