Cognitive and morphometric features of mild cognitive impairment reversion in early patients with Parkinson's disease

Mild cognitive impairment is a common feature of Parkinson's disease (PD-MCI), even at the earliest disease stages. Growing evidence supports the instability of PD-MCI over time, without a consistent linear evolution to dementia, and in some patients, the potential of reversion to normal cognition. However, which features are associated with reversion from PD-MCI to normal cognition in early PD-MCI are not fully known.

In our longitudinal study of early drug naïve PD patients, 65 of 134 (48 %) patients had PD-MCI at baseline. Study participants underwent comprehensive assessments at baseline and 1-year follow-up. Sixteen (24.6 %) patients with PD-MCI reverted to normal cognition (Reverters), and 49 (75.4 %) had persistent PD-MCI (Non-Reverters) after 1-year follow-up. We performed single- and multiple-variable logistic regression analyses to identify baseline variables predicting reversion of PD-MCI to normal cognition after 1-year. We also compared brain morphometric measures (cortical thickness and volumes) at baseline between the PD-MCI Reverters and Non-Reverters.

Higher educational level and better performance on measures of attention and memory at baseline predicted the reversion to normal cognition at 1-year follow-up. Reverters had greater cortical thickness in the left inferior temporal gyrus than Non-Reverters.

Our results show PD-MCI with a higher chance of reverting to normal cognition over time have a higher educational level, better frontotemporal-related cognitive function, and increased thickness of the inferior temporal lobe gyrus. These findings may potentially help researchers to select the candidates for clinical trials focusing on the treatment of cognitive impairment in the early stages of PD.