Narrative discourse cohesion in early stage Parkinson's disease

Abstract

Models of basal ganglia (BG) function suggest that expressive language deficits will likely and consistently present in BG disease. Disparities currently exist between the predictions of models of BG function in expressive language and data from studies of BG disease. Traditional expressive language assessment methodologies that emphasize measures of language form (word and sentence productivity) while not carefully considering how language is used, may only partially account for these disparities. Objective: To use measures of cohesion to examine the use of cohesive markers in narrative discourse. Methods: Twelve individuals with idiopathic Parkinson's disease (PD) were compared to 12 matched neurologically intact controls on measures of discourse performance. Three discourse samples (typical day, memorable vacation and family) were analyzed for measures of narrative productivity, number of cohesive ties and cohesive adequacy. Mixed model analyses were completed for group comparisons. Results: Group differences were not observed on measures of language form as measured by narrative productivity, communication units, and number of cohesive ties produced. In contrast, group differences were observed in cohesive adequacy as individuals with PD produced a higher percentage of incomplete and erroneous cohesive ties relative the control subjects across narratives. Conclusions: These results support the conclusion that the BG in PD may have an executive role in expressive language use that can be disrupted without impacting language form.