Narrative abilities in Parkinson's disease:A pilot study on italian-speaking patients treated with deep brain stimulation of the subthalamic nucleus

Language and communication impairments can be observed among the non-motor features of Parkinson’s Disease (PD), frequently associated with cognitive decline. Few studies examined whether pharmacologic and surgical treatments (e.g. Deep Brain Stimulation of the subthalamic nucleus, STN-DBS) can influence these symptoms, and the results are mostly contradictory. This explorative study aims to deepen the linguistic and communicative profile of PD, providing a general description of patients’ narrative abilities during a story generation task. The analysis observed the effects of different therapeutic treatments (dopaminergic medications vs. STN-DBS) on four narrative dimensions: general productivity, textual coherence, linguistic cohesion, and psychological lexicon (i.e. a measure of the occurrence of lexemes concerning the mental states of the characters). The results showed that PD patients with pharmacologic treatment performed worse than controls in general productivity, whereas patients treated with STN-DBS were significantly impaired in selecting narrative units during the plotline construction (textual coherence) and in expressing emotional mental states (psychological lexicon). Despite the small sample size, these findings, still preliminary, offer new perspectives in the research on the pragmatic profile of patients with PD and the cognitive substrates of discourse production.