Objective: To investigate whether subjective cognitive complaints assessed by the Non-Motor Symptoms Scale (NMSS) are predictive of longitudinal cognitive trajectories in cognitively intact people with Parkinson’s (PwP).

Background: Evidence suggests that subjective cognitive complaints (SCC), reported in the absence of a manifest objective cognitive impairment, may be a harbinger of future cognitive decline in Parkinson’s disease (PD) [1]. Reliable tools for the assessment or screening of SCC in PD are currently lacking [2], and identification of this potential predictor of cognitive decline in clinical practice is an unmet need.

Method: Data for this study were obtained from the Non-Motor Longitudinal International Study (NILS, initiated in 2010). We included PwP with a diagnosis of idiopathic PD according to the UK Brain Bank criteria and a Mini-Mental State Examination (MMSE) score of 30 at baseline, indicating the absence of any cognitive disorder on a screening basis [3]. The Attention/Memory domain (Domain 5) of the NMSS [4] evaluates subjective memory and attentional issues over the previous month using a score based on the frequency and severity of complaints (total domain score range 0-36). The relationship of baseline NMSS Domain 5 with longitudinal changes in MMSE scores was assessed using linear mixed effects models (LMM) and adjusting for potential confounders (age, sex, education, motor function and depression).

Results: A total of 413 PwP [median age 64.4 (56.0-70.7)] and up to 3 years of follow-up were included in the current analysis (Table 1). A first LMM, which included the NMSS Domain 5 score as continuous predictor of MMSE decline, displayed a significant interaction between time and NMSS Domain 5 score (p=0.004) (Table 2). Similarly, when the NMSS Domain 5 was used as categorical predictor for the absence (0) or presence (≥1) of any cognitive complaints in a second LMM, a significant interaction with time was confirmed (p=0.016) (Table 2, Figure).

Conclusion: Although in our cohort we detected a mild decline in MMSE score after 3 years, our findings suggest that in PwP without manifest cognitive impairment the assessment of SCC using specifically Domain 5 of NMSS may provide insights into future cognitive progression and offer opportunities for potential early therapeutic interventions.

References: 1. Purri R, Brennan L, Rick J, Xie SX, Deck BL, Chahine LM, Dahodwala N, Chen-Plotkin A, Duda JE, Morley JF, Akhtar RS, Trojanowski JQ, Siderowf A, Weintraub D. Subjective Cognitive Complaint in Parkinson’s Disease Patients With Normal Cognition: Canary in the Coal Mine? Mov Disord. 2020 Sep;35(9):1618-1625. doi: 10.1002/mds.28115. Epub 2020 Jun 10. PMID: 32520435; PMCID: PMC7722141. 2. Kjeldsen PL, Damholdt MF. Subjective cognitive complaints in patients with Parkinson’s disease. Acta Neurol Scand. 2019 Dec;140(6):375-389. doi: 10.1111/ane.13158. Epub 2019 Oct 9. PMID: 31433855. 3. Hoops S, Nazem S, Siderowf AD, Duda JE, Xie SX, Stern MB, Weintraub D. Validity of the MoCA and MMSE in the detection of MCI and dementia in Parkinson disease. Neurology. 2009 Nov 24;73(21):1738-45. doi: 10.1212/WNL.0b013e3181c34b47. PMID: 19933974; PMCID: PMC2788810. 4. Chaudhuri KR, Martinez-Martin P, Brown RG, Sethi K, Stocchi F, Odin P, Ondo W, Abe K, Macphee G, Macmahon D, Barone P, Rabey M, Forbes A, Breen K, Tluk S, Naidu Y, Olanow W, Williams AJ, Thomas S, Rye D, Tsuboi Y, Hand A, Schapira AH. The metric properties of a novel non-motor symptoms scale for Parkinson’s disease: Results from an international pilot study. Mov Disord. 2007 Oct 15;22(13):1901-11. doi: 10.1002/mds.21596. PMID: 17674410.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/subjective-cognitive-complaints-assessed-with-the-cognitive-domain-of-the-non-motor-symptoms-scale-predict-longitudinal-cognitive-trajectory-in-people-with-parkinsons-disease-with-normal-cogn/