Production and comprehension of co-speech gestures in Parkinson's disease

This study examined how impairments in sensorimotor abilities of individuals with Parkinson's Disease (PD) can be related to the use and understanding of co-speech hand gestures involving literal and figurative actions. We tested individuals with PD (n = 18, 12 males, M_age = 56.5, SD_age = 8.16, PD duration since onset: M = 5.36 years, SD = 3.51, Hoehn and Yahr Scale:M_H&Y = 2.09, SD_H&Y = 0.50) and age- and education-matched neurotypical controls (n = 18, 14 males, M_age = 56.61, SD_age = 8.88) with two experimental tasks. In the gesture production task, participants retold the narratives presented to them in a written format. In the gesture comprehension task, participants were asked to match a gesture with a novel verb in literal and figurative sentence contexts. Results showed that patients with PD gestured significantly less than the neurotypical controls. No group differences were found for the type of gesture use. Individuals with PD performed worse than controls on matching gestures with novel verbs, particularly for figurative meanings. Individuals' severity in the disease negatively correlated with their performance for these figurative novel verb-gesture matches. The performances in the two tasks did not correlate. These findings suggest that problems in sensorimotor abilities resulting from PD can influence overall gesture production and gesture comprehension, providing further evidence on the relations between PD and the impaired use of multimodal language.