Congruency and Emotional Valence Effects on Speech Production in Individuals with Parkinson's Disease

Individuals with Parkinson's disease (PD) exhibit a variety of impairments in nonmotor symptoms including emotional processing and cognitive control that have implications for speech production. The present study sought to investigate whether impairments in cognitive processing in individuals with PD impact emotional sentence production as indicated by changes in speech rate. Thirty-six individuals (20 individuals with PD, 16 healthy controls) completed subtests 8A and 8B of the Florida Emotional Expressive Battery (FEEB) to elicit speech samples in five different emotional tones (happy, sad, angry, fear, and neutral). Sentences contained either semantically emotional or neutral information, resulting in conditions of congruency (same semantics-tone) and incongruency (different semantics-tone). Speech rate was impacted by the emotional tone of all participants. Individuals with PD demonstrated faster speech rates under conditions of conflicting semantic information than healthy older adults. Changes in speech rate under emotional conditions were not influenced by global measures of cognition or depression. The results of this study indicate that individuals with PD struggle to manage irrelevant information present during emotional speech production. Speech rate is a simple, easy-to-measure metric that may reflect cognitive processing impairments in PD.