The organization of narrative discourse in Lewy body spectrum disorder

► We examined narrative discourse in patients with Lewy body spectrum disorder. ► Lewy body disease and PD with dementia patients show impaired narrative organization. ► Their narrative organization is correlated with deficits in executive functioning. ► Their impaired discourse cohesion is related to reduced frontal cortical volume. ► Narrative discourse includes both linguistic and non-linguistic components. Narrative discourse is an essential component of day-to-day communication, but little is known about narrative in Lewy body spectrum disorder (LBSD), including Parkinson’s disease (PD), Parkinson’s disease with dementia (PDD), and dementia with Lewy bodies (DLB). We performed a detailed analysis of a semi-structured speech sample in 32 non-aphasic patients with LBSD, and we related their narrative impairments to gray matter (GM) atrophy using voxel-based morphometry. We found that patients with PDD and DLB have significant difficulty organizing their narrative speech. This was correlated with deficits on measures of executive functioning and speech fluency. Regression analyses associated this deficit with reduced cortical volume in inferior frontal and anterior cingulate regions. These findings are consistent with a model of narrative discourse that includes executive as well as language components and with an impairment of the organizational component of narrative discourse in patients with PDD and DLB.