Highlights
- •Working memory may separate true SWEDDs from PD patients and healthy controls.
- •True SWEDDS show similar baseline cognition to non-true SWEDDs.
- •True SWEDDs, PD patients and controls show decline in working memory with time.
- •In contrast, non-true SWEDDs show stable cognitive symptoms with time.
Abstract
Introduction
The cognitive profile of patients with longstanding clinical Parkinsonism possessing
scans without evidence of dopaminergic deficit (SWEDD) remains unclear from previous
studies.
Methods
We studied 47 patients recruited in the Parkinson's Progression Markers Initiative
with SWEDD as baseline diagnosis. They were subdivided by final clinical diagnoses
after a 2-year follow-up period into 25 patients with either clinical evidence of
Parkinson's Disease (PD) or unclassified parkinsonism and normal SPECT imaging (“true
SWEDDs”), 6 patients with a psychogenic illness exhibiting Parkinsonism, 6 patients
who had phenoconverted to PD based on reduced striatal dopaminergic activity on imaging,
and 10 patients with another tremulous condition. Cognitive symptoms were compared
between these subgroups, as well as with 62 PD patients and 195 healthy controls (HCs),
at baseline and follow-ups.
Results
A significant difference in working memory was found between true SWEDDs and HCs (P = 0.009), but not true SWEDDs and PD patients (P = 0.432), nor PD patients and HCs (P = 0.154). The prevalence of attentional impairment was also significantly different
between the three groups (P < 0.001). SWEDD subgroups possessed similar cognitive symptoms irrespective of their
final clinical diagnosis. Psychogenic, phenoconverted and tremulous SWEDDs also possessed
stable cognitive symptoms over the 2-year period whilst true SWEDDs, PD patients and
HCs experienced significant changes in working memory.
Conclusions
Our results, particularly relating to working memory and attention, add to the knowledge
of other true SWEDD non-motor symptoms to facilitate earlier diagnosis and improved
management strategies for these patients.
Keywords
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Article info
Publication history
Published online: July 25, 2022
Accepted:
July 20,
2022
Received in revised form:
June 9,
2022
Received:
March 13,
2022
Identification
Copyright
© 2022 Elsevier B.V. All rights reserved.
