Objective: ​​​​​To compare 3 scales which have been used in literature to determine subjective cognitive complaints (SCC) in Parkinson’s disease (PD) and explore their relationship with mild cognitive impairment (PD-MCI) at baseline within a single cohort.

Background: SCC is common in PD: the presence of SCC may indicate current and future cognitive impairment, but is also suggested to be associated with affective rather than cognitive symptoms [1]. Several tests have been used to determine the presence of SCC in PD; the ideal method is unclear.

Method: We compare 3 methods of determining SCC in early PD patients in the Early Parkinson’s Disease Longitudinal Singapore (PALS) Study cohort and their association with PD-MCI at baseline. The presence of SCC was defined using the MDS-UPDRS Question 1.1 score of 1 or more, Non-Motor Symptoms Scale (NMSS) Domain-5 score of 1 or more, or any positive response to 3 subjective questions on cognition. Neuropsychological testing (NPT) was performed to ascertain the presence of PD-MCI according to MDS Level II criteria[2].

Results: 200 early PD patients (57.5% male) were studied. Mean age was 63.8±9.0 years and mean disease duration was 4.9±3.4 months. Participants had a mean of 10.6±4.4 years of education. At baseline, 21.5%, 44.0% and 32.0% reported SCC using the MDS-UPDRS Question 1.1, Non-Motor Symptoms Scale (NMSS) Domain-5, and the 3 subjective questions respectively. 51.5% met criteria for PD-MCI on NPT. There was mild correlation between UPDRS Question 1.1 and NMSS Domain-5 (r=0.47, p<0.01) but poor correlation between the 3 subjective questions and others. Of those with baseline PD-MCI on NPT, 27.2%, 43.7% and 35.9% of patients reported SCC using the UPDRS Question 1.1, NMSS Domain-5 and the 3 subjective questions respectively. 34.0% of those with PD-MCI on NPT did not endorse SCC on any measure.

Conclusion: The different methods used to detect SCC in early PD are poorly correlated despite the similarity of the questions. The factors determining the presence of SCC are complex and may reflect co-morbidity such as anxiety or depression. Amongst those with NPT-detected MCI, SCC was best detected using NMSS Domain-5, but sensitivity remained low. A significant proportion with NPT-determined PD-MCI do not report SCC; relying on self-reported SCC may not accurately reflect presence of current or risk of future cognitive impairment.

References: 1. Siciliano M, Tessitore A, Morgante F, Goldman JG, Ricciardi L. Subjective Cognitive Complaints in Parkinson’s Disease: A Systematic Review and Meta-Analysis. Movement Disorders. 2024;39(1):17-28. doi:10.1002/mds.29649
2. Litvan I, Goldman JG, Tröster AI, et al. Diagnostic Criteria for Mild Cognitive Impairment in Parkinson’s Disease: Movement Disorder Society Task Force Guidelines. Mov Disord. 2012;27(3):349-356. doi:10.1002/mds.24893

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MDS Abstracts - https://www.mdsabstracts.org/abstract/comparison-of-3-tests-for-subjective-cognitive-complaints-in-early-parkinsons-disease/