MIAMI—Among patients with Parkinson’s disease–associated mild cognitive impairment (MCI), Montreal Cognitive Assessment (MoCA) subscores in visuospatial function, attention, language, and orientation are the most useful in predicting conversion to dementia, according to research presented at the First Pan American Parkinson’s Disease and Movement Disorders Congress. Melissa Mackenzie, of the Division of Neurology at the University of British Columbia in Vancouver, Canada, and colleagues conducted a study to evaluate which subscores on the cognitive assessment predict conversion to dementia in patients with Parkinson’s disease–associated MCI.
The investigators searched the Pacific Parkinson’s Research Centre Database to identify patients with a diagnosis of idiopathic Parkinson’s disease who completed an itemized MoCA in the MCI range (ie, they had a corrected total score between 21 and 27) and who completed at least one other MoCA at least one year later. Patients taking potentially cognitive enhancing medications were excluded.
The researchers included in their study 529 assessments from 164 patients. They separated patients into three groups based on their last MoCA score—those who developed dementia (33 patients), those who returned to normal cognition (48 patients), and those who maintained MoCA scores in the MCI range (83 patients). In a model that predicted future MoCA score categories with 78% accuracy, the most important subscores were visuospatial, attention, language, and orientation, “but, interestingly, not delayed recall,” Dr. Mackenzie and colleagues said.
“A prevailing theory of cognitive decline in Parkinson’s disease postulates that visuospatial ‘posterior-cortical’ impairments are due to Lewy body deposition, whereas frontal executive dysfunction reflects ‘on–off’ state,” the researchers said. “Interestingly, language scores and memory function in delayed recall were the items that improved the most” in patients who reverted from MCI to normal cognition. “Whether the best approach to assess risk of conversion to dementia is to focus exclusively on these MoCA sections, or alternatively, employing multiple tests that target these cognitive domains, remains to be seen,” the researchers concluded. Patients with Parkinson’s disease–associated MCI at any time “should likely be followed more closely for cognitive decline, as they seem to be at increased risk for developing dementia, even if there is interval maintenance of MCI or return to normal cognition.”
—Jake Remaly
