In keeping with prior studies in Parkinson disease (PD), executive dysfunction seems to underpin performance of many items of the Montreal Cognitive Assessment (MoCA), a recent study found. Researchers analyzed item responses from the MoCA in 357 individuals with PD from the Parkinson's Progression Markers Initiative for frequency of errors and polychoric inter-item correlations. This correlation matrix was then analyzed with exploratory factor analysis. They found:

• Factor analysis revealed that the MoCA is explained by 3 factors in early PD; these factors were reflective of executive dysfunction, memory, and verbal attention.
• Scores on the MoCA and all of its subscales were significantly different between individuals with PD and no cognitive impairment and those who met criteria for mild cognitive impairment.