Among individuals across a spectrum of risk for Parkinson disease (PD), cognitive function is worse among those with the characteristic most strongly associated with future risk of PD or dementia with Lewy bodies, namely REM sleep behavior disorder (RBD), a recent study found.
Participants belonging to the following cohorts of the Parkinson Progression Markers Initiative (PPMI) study were included: de novo PD with dopamine transporter binding deficit (n=423), idiopathic RBD (n=39), hyposmia (n=26), and non-PD mutation carrier (NMC; Leucine-rich repeat kinase 2 G2019S [n=88] and glucocerebrosidase [GBA] gene [n=38] mutations). Researchers found:
- The RBD cohort performed significantly worse than the hyposmia and NMC cohorts on Symbol Digit Modality Test and Judgment of Line Orientation.
- The RBD cohort also performed worse than the hyposmia cohort on the Montreal Cognitive Assessment.
- Hyposmics did not differ from PD or NMC cohorts on any cognitive test score.
Chahine LM, Urbe L, Caspell-Garcia C, et al, the Parkinson’s Progression Markers Initiative. Cognition among individuals along a spectrum of increased risk for Parkinson’s disease. [Published online ahead of print August 20, 2018]. PLoS One. doi:10.1371/journal.pone.0201964.