OBJECTIVES: The worldwide spread of Parkinson's disease (PD) calls for sensitive 
and specific measures enabling its early (or, ideally, preclinical) detection. 
Here, we use language measures revealing deficits in PD to explore whether 
similar disturbances are present in asymptomatic individuals at risk for the 
disease.
METHODS: We administered executive, semantic, verb-production, and syntactic 
tasks to sporadic PD patients, genetic PD patients with PARK2 (parkin) or LRRK2 
(dardarin) mutation, asymptomatic first-degree relatives of the latter with 
similar mutations, and socio-demographically matched controls. Moreover, to 
detect sui generis language disturbances, we ran analysis of covariance tests 
using executive functions as covariate.
RESULTS: The two clinical groups showed impairments in all measures, most of 
which survived covariation with executive functions. However, the key finding 
concerned asymptomatic mutation carriers. While these subjects showed intact 
executive, semantic, and action-verb production skills, they evinced deficits in 
a syntactic test with minimal working memory load.
CONCLUSIONS: We propose that this sui generis disturbance may constitute a 
prodromal sign anticipating eventual development of PD. Moreover, our results 
suggest that mutations on specific genes (PARK2 and LRRK2) compromising basal 
ganglia functioning may be subtly related to language-processing mechanisms. 
(JINS, 2017, 23, 150-158).