Scientific article
Open access

Distinctive clinical and imaging trajectories in SWEDD and Parkinson's disease patients

Published inNeuroImage. Clinical, vol. 42, 103592
Publication date2024-03-14
First online date2024-03-14

A proportion of patients clinically diagnosed with Parkinson's disease (PD) can have a123I-FP-CIT-SPECT scan without evidence of dopaminergic deficit (SWEDD), generating a debate about the underlying biological mechanisms. This study investigated differences in clinical features,123I-FP-CIT binding, molecular connectivity, as well as clinical and imaging progression between SWEDD and PD patients. We included 36 SWEDD, 49 de novo idiopathic PD, and 49 healthy controls with123I-FP-CIT-SPECT from the Parkinson's Progression Markers Initiative. Clinical and imaging 2-year follow-ups were available for 27 SWEDD and 40 PD. Regional-based and voxel-wise analysis assessed dopaminergic integrity in dorsal and ventral striatal, as well as extrastriatal regions, at baseline and follow-up. Molecular connectivity analyses evaluated dopaminergic pathways. Spatial correlation analyses tested whether123I-FP-CIT-binding alterations would also pertain to the serotoninergic system. SWEDD and PD patients showed comparable symptoms at baseline, except for hyposmia, which was more severe for PD. PD showed significantly lower striatal and extrastriatal123I-FP-CIT-binding compared to SWEDD and controls. SWEDD exhibited lower binding than controls in striatal regions, insula, and olfactory cortex. Both PD and SWEDD showed extensive altered connectivity of dopaminergic pathways, however, with major impairment in the mesocorticolimbic system for SWEDD. Motor symptoms and dopaminergic deficits worsened after 2 years for PD only. The limited dopaminergic impairment and its stability over time observed for SWEDD, as well as the presence of extrastriatal123I-FP-CIT binding alterations and prevalent mesocorticolimbic connectivity impairment, suggest other mechanisms contributing to SWEDD pathophysiology.

  • (123)I-FP-CIT SPECT
  • Molecular connectivity
  • Neurotransmission
  • Parkinson's disease
  • Scans without evidence of dopaminergic deficit (SWEDD)
Citation (ISO format)
BOCCALINI, Cécilia et al. Distinctive clinical and imaging trajectories in SWEDD and Parkinson’s disease patients. In: NeuroImage. Clinical, 2024, vol. 42, p. 103592. doi: 10.1016/j.nicl.2024.103592
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ISSN of the journal2213-1582

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