Objective: We studied the causal relations between various external factors and MoCA subscores using Bayesian networks.

Background: The MoCA is a standard screening test for cognitive impairment in PD. However, MoCA scores are usually assessed in isolation, without consideration of the influences of other factors such as gender, depression and/or disease severity.

Methods: We pooled data from the Parkinson’s Progression Markers Initiative (PPMI, n = 830) and the Pacific Parkinson’s Research Centre (PPRC, n = 529) as the PPMI data mostly had patients with mild disease.  We included all Parkinson’s disease patients who were assessed with a MoCA (Montreal cognitive assessment), and depression rating scale (Beck’s depression inventory or Geriatric Depression Scales). Patients who were on medications for dementia (acetylcholinesterase inhibitors or memantine) when the cognitive assessment were excluded as this may independently influence the total MoCA score. Other demographic variables (including gender, age, years of education), MoCA test subscores, and PD related features such as age of onset and LEDD were obtained. The demographic factores and MoCA subscores resulted in 16 variables and directed (causal) probabilistic relations were determined between variables using a Bayesian Network approach.

Results: A Bayesian network was obtained based on the pooled data (Fig-1). Gender, independent of other factors, had an influence on LEDD, as well as orientation and abstraction sub-scores. LEDD had independent effect on orientation, while BDI/GDS affected verbal fluency.

Conclusions: Based on > 1300 subjects, we found a significant impact of gender on orientation and abstraction, possibly due to hormonal influences. Presumably the gender influences on LEDD are a result of the reduced body mass in females. Depression, as indexed by the BDI/GDS, had the greatest impact on verbal fluency. Interestingly, depression influenced age of onset, implying that depression may represent an independent risk factor for development of PD. LEDD had a significant impact on orientation, consistent previous reports of L-dopa effects on working memory. Our results suggest that MoCA scores may need to be considered in the context of  gender, depression and medication status.

References: Uc EY, McDermott MP, Marder KS, Anderson SW, Litvan I, Como PG, Auinger P, Chou KL, Growdon JC, Parkinson Study Group DATATOP Investigators. Incidence of and risk factors for cognitive impairment in an early Parkinson disease clinical trial cohort. Neurology. 2009 Nov 3;73(18):1469-77.
Xu Y, Yang J, Shang H. Meta-analysis of risk factors for Parkinson’s disease dementia. Translational neurodegeneration. 2016 Jun 1;5(1):1.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/influences-of-gender-depression-and-disease-severity-on-moca-subscores-in-parksinons-disease/